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Lossy Audio Compression => Ogg Vorbis => Ogg Vorbis - General => Topic started by: Gabriel on 2003-09-25 14:37:05

Title: Vorbis development, status & patent issues
Post by: Gabriel on 2003-09-25 14:37:05
Moderator comment
Currently the Vorbis patent issue covers these threads:
Vorbis development, status & patent issues PART 1 - NON-technical discussion (http://www.hydrogenaudio.org/forums/index.php?showtopic=13686)
Vorbis development, status & patent issues PART 2 - Technical discussion (This thread) (http://www.hydrogenaudio.org/forums/index.php?showtopic=13531)
/Moderator comment

By looking at this:
http://www.xiph.org/archives/vorbis-dev/20...2/index.html#83 (http://www.xiph.org/archives/vorbis-dev/200012/index.html#83)
it seems that Xiph (at least in 2000) was open to the idea of disclosing the patent research.
Is this position changed now, or does it still stand?
Title: Vorbis development, status & patent issues
Post by: c_haese on 2003-09-25 14:43:19
Quote
you are not capable of scientific discussion, and that is what HA forum is about.

Fair enough, let's start a scientific discussion.

You have mentioned a patent on switched MDCT filterbanks with overlap and add. It is a scientific fact that Vorbis uses a similar method.

Now, does this prove whether or not Vorbis infringes on this patent? No. One has to look at the specific claims in the patent, and the specific methods used by Vorbis. Unless somebody brings credible evidence that there is a specific claim in the patent that Vorbis specifically infringes, I must assume that Monty is aware of this patent (he'd be a fool not to be aware of it, since it is so blatantly similar), and determined that it does not apply to Vorbis, since I am unfortunately not qualified to make such a determination myself.

I would like to hear Monty and/or Jack's opinion about this, but they are currently not available for comment. However, at least Jack will be at the Monthly Meeting.

I am sorry if I personally insulted anyone, that was not my intention. I happen to be a strong believer in the need for patent-free technology, and I do apologize if my passion for this cause has gotten the best of me.
Title: Vorbis development, status & patent issues
Post by: Ivan Dimkovic on 2003-09-25 14:53:46
Quote
Fair enough, let's start a scientific discussion.


Ok, Great :-)

Quote
You have mentioned a patent on switched MDCT filterbanks with overlap and add. It is a scientific fact that Vorbis uses a similar method.

Now, does this prove whether or not Vorbis infringes on this patent? No. One has to look at the specific claims in the patent, and the specific methods used by Vorbis. Unless somebody brings credible evidence that there is a specific claim in the patent that Vorbis specifically infringes, I must assume that Monty is aware of this patent (he'd be a fool not to be aware of it, since it is so blatantly similar), and determined that it does not apply to Vorbis, since I am unfortunately not qualified to make such a determination myself.


It has been brought:

US 5,214,742

Page 7 (Claims)

Claim 1, maybe 2 , Claim 3, Claim 4, 5, 6, maybe 7, 8, 9

They might look pretty much applicable in Vorbis IMHO, at least by brief looking at block.c  and window.c  in Vorbis CVS.

Quote
I would like to hear Monty and/or Jack's opinion about this, but they are currently not available for comment. However, at least Jack will be at the Monthly Meeting.


Great!

Quote
I am sorry if I personally insulted anyone, that was not my intention. I happen to be a strong believer in the need for patent-free technology, and I do apologize if my passion for this cause has gotten the best of me.


Well, being a believer is one thing - it interferes with science a lot  But certainly is a virtue, no matter how good is the cause
Title: Vorbis development, status & patent issues
Post by: Ivan Dimkovic on 2003-09-25 14:59:02
One more thing - the claims are not related to any specific windowing function,  claim 1 states that resultant of the window function equals 1,  and does not state any specific window function - SIN, SIN^2, KBD and any other satisfy this.  And I believe that Vorbis window function also satisfies this, otherwise it wouldn't be perfect-reconstruction filterbank.
Title: Vorbis development, status & patent issues
Post by: menno on 2003-09-25 15:20:39
Claim 1 from patent US5214742:
Quote
1. In a method of transmitting a signal including the steps of dividing the signal into successive, overlapping blocks by means of windows, converting the partial signals contained in the blocks into a spectrum by transformation utilizing window functions within the respective said windows such that the resultant of the window functions in the respective overlapping regions of successive blocks equals 1, subsequently, coding and transmitting the resulting spectra, receiving and decoding the transmitted coded spectra, converting the decoded spectra back into partial signals by transformation, and finally, joining the blocks containing the partial signals in an overlapping manner; the improvement comprising selecting the length of the respective window functions as a function of signal amplitude changes.


Then block.c in Vorbis source code does overlap/add and windowing from line 722 to 758 (latest CVS nightly).
Code: [Select]
    for(j=0;j<vi->channels;j++){
     /* the overlap/add section */
     if(v->lW){
    if(v->W){
  /* large/large */
  float *w=_vorbis_window_get(b->window[1]-hs);
  float *pcm=v->pcm[j]+prevCenter;
  float *p=vb->pcm[j];
  for(i=0;i<n1;i++)
    pcm[i]=pcm[i]*w[n1-i-1] + p[i]*w[i];
    }else{
  /* large/small */
  float *w=_vorbis_window_get(b->window[0]-hs);

etc...

And of course it does MDCT. Now the only possibility I see that this doesn't infringe the patent is if the window does not behave as claimed in the patent.

Menno
Title: Vorbis development, status & patent issues
Post by: menno on 2003-09-25 15:41:45
1.3. High-level Decode Process (http://www.xiph.org/ogg/vorbis/doc/Vorbis_I_spec.html#id5372250)

It seems that the Vorbis specification itself gives the answer about the window function, see 1.3.2.3.

Menno
Title: Vorbis development, status & patent issues
Post by: Ivan Dimkovic on 2003-09-25 15:43:19
Ok, so we have a pretty clear basis for a serious scientific discussion, eh c_haese?
Title: Vorbis development, status & patent issues
Post by: c_haese on 2003-09-25 16:03:20
I've already said everything I'm qualified to say. When there are details, you'll hear about them then.
Title: Vorbis development, status & patent issues
Post by: Ivan Dimkovic on 2003-09-25 16:14:21
Well, at least there is a nice bunch of factual data about US5214742 that needs to be proven as not relevant - altough I believe that most claims of the patent are probably met in a nice way

Of course... there might be some hidden catch and really the way to avoid it - and I really think that Xiph guys thought about how to avoid that one, but  let's wait the official response and a nice and polite scientific discussion,  if someone decides to answer in a scientific  not the personal way like done by now.

Everyone interested can view the patent: 

http://ep.espacenet.com/ (http://ep.espacenet.com/)  and type the US5214742 in the "View the patent application" box

Vorbis code that deals with MDCT overlap/add and switching is in files: block.c and window.c  IMHO
Title: Vorbis development, status & patent issues
Post by: petracci on 2003-09-25 16:50:13
Quote
There are some importaint points made with references to the real-world code and patent applications - they are not "gee" claims,  they are based on a relevant observations and not made up -  IMHO, they are a nice basis for a good discussion towars ability to make a MDCT window switched codec (like MP3/AAC/Vorbis/WMA actually are) without infringing cited patent.

I followed your link to the actual patent and would like to share my views on the patent.

Claim 1 does not claim the "windowing/overlap-add" method but an improvement where the length of the window is selected based on a function of signal amplitude changes. By choosing a different window length selection algorithm, one could prevent infringing the patent.

Claim 4 is IMO more difficult to circumvent, since it seems to describe how to obtain transition windows.

I saw that Bernd Edler is the inventor here, since I will see him in November, I could ask for his opinion on this (he is familiar with the Vorbis codec).
Title: Vorbis development, status & patent issues
Post by: Ivan Dimkovic on 2003-09-25 16:56:41
Quote
Claim 1 does not claim the "windowing/overlap-add" method but an improvement where the length of the window is selected based on a function of signal amplitude changes. By choosing a different window length selection algorithm, one could prevent infringing the patent.


Claim 1 says:

Quote
1. In a method of transmitting a signal including the steps of dividing the signal into successive, overlapping blocks by means of windows, converting the partial signals contained in the blocks into a spectrum by transformation utilizing window functions within the respective said windows such that the resultant of the window functions in the respective overlapping regions of successive blocks equals 1, subsequently, coding and transmitting the resulting spectra, receiving and decoding the transmitted coded spectra, converting the decoded spectra back into partial signals by transformation, and finally, joining the blocks containing the partial signals in an overlapping manner; the improvement comprising selecting the length of the respective window functions as a function of signal amplitude changes.


Yes, I stand corrected -

Regarding the switching criteria - it is pretty much general, as it just says that the switching is based on signal amplitude change - PE method falls to this category as well, and most methods degrade to this basic claim, no matter what kind of switching criteria they use - it is always matter of energy (amplitude) change.
Title: Vorbis development, status & patent issues
Post by: petracci on 2003-09-25 17:07:53
Quote
Regarding the switching criteria - it is pretty much general, as it just says that the switching is based on signal amplitude change - PE method falls to this category as well, and most methods degrade to this basic claim, no matter what kind of switching criteria they use - it is always matter of energy (amplitude) change.

First of all, do you also think that claim 1 is about the switching and not the windowing/overlap-add?

As for the switching selection, you could do it based on coding results, so compare the number of bits used when a long window was selected with the number of bits used when 2 short windows are selected (for the case where the short window is half the length of the long window). This is not nearly as efficient as most functions of energy change, but IMO different and not falling under claim 1.
Title: Vorbis development, status & patent issues
Post by: Ivan Dimkovic on 2003-09-25 17:22:15
Quote
First of all, do you also think that claim 1 is about the switching and not the windowing/overlap-add?


Yes I agree, it is related to improvement based on switching ot short blocks.

Quote
As for the switching selection, you could do it based on coding results, so compare the number of bits used when a long window was selected with the number of bits used when 2 short windows are selected (for the case where the short window is half the length of the long window). This is not nearly as efficient as most functions of energy change, but IMO different and not falling under claim 1.


Can be done like that - I am not a vorbis expert but it seems they do switching based on envelope band energy level difference (envelope.c)  if that is actually used for window switching, and I don't know that - anyway that is not patented as far as it can't be interpreted as "signal amplitude".

But the claim 4 is kinda hard to avoid. Same for claim 6.
Title: Vorbis development, status & patent issues
Post by: petracci on 2003-09-25 17:34:24
Yes, Claim 4 is not easy to avoid. Claim 6 points back to Claim 2, where again the issue of changing signal amplitudes is mentioned.

Hmm, but Claim 4 points back to Claim 3, which points back to...etc,etc.

If presented with the vorbis code (and possibly an explanation of its operation) and a certain patent, I would find it very hard to make any judgement still, due to the language used in patent documents.
Title: Vorbis development, status & patent issues
Post by: c_haese on 2003-09-25 17:36:25
Quote
(snip) anyway that is not patented as far as it can't be interpreted as "signal amplitude".

But the claim 4 is kinda hard to avoid. Same for claim 6.

Wouldn't all claims have to apply to make Vorbis infringing on this patent? Otherwise I could patent a piece of software, state in claim 1 that it is a method to be performed by an electronic computing device, and *BAM* I've patented all computer software ever written and ever to be written in one fell swoop, regardless of whether the other claims apply.
Title: Vorbis development, status & patent issues
Post by: Ivan Dimkovic on 2003-09-25 18:30:35
Quote
Wouldn't all claims have to apply to make Vorbis infringing on this patent


I'm not a patent laywer, I just posted some interesting findings regarding this patent and vorbis code -  I think vorbis developers know how they avoided it, so they can certainly shed some light on the issue.

Quote
I could patent a piece of software, state in claim 1 that it is a method to be performed by an electronic computing device, and *BAM* I've patented all computer software ever written and ever to be written in one fell swoop, regardless of whether the other claims apply.


No,  all claims must not be prior-art  so your claim is pointless
Title: Vorbis development, status & patent issues
Post by: jmvalin on 2003-09-25 23:31:53
Quote
Yes, Claim 4 is not easy to avoid. Claim 6 points back to Claim 2, where again the issue of changing signal amplitudes is mentioned.

Hmm, but Claim 4 points back to Claim 3, which points back to...etc,etc.

If presented with the vorbis code (and possibly an explanation of its operation) and a certain patent, I would find it very hard to make any judgement still, due to the language used in patent documents.

Actually, the way patents work is that to infringe on a patent, you need to infringe on *any* of the claims. However, to infringe on a claim, you have to do something that fits the *totality* of the claim. In this case, I would say that Vorbis doesn't infringe on claim 1, due to the "as a function of signal amplitude changes" (which probably needs to be there because there would likely be prior art for the general case). If Vorbis doesn't infringe on 1, then it automatically doesn't infringe on the others because all the others include 1.

Now, why would they bother making all the other claims dependent on 1 if the fact of not infringing on 1 prevents infringement on the others? The reason is that in probably think 1 may have prior art, in which case, the other claims are still valid (provided there's no prior art on them). Otherwise, prior art on 1 would have totally invalidated the patent. Anyway, the result is still that if Vorbis doesn't infringe on 1, it's safe from 5,214,742.
Title: Vorbis development, status & patent issues
Post by: JohnV on 2003-09-26 00:23:22
Quote
Quote
Yes, Claim 4 is not easy to avoid. Claim 6 points back to Claim 2, where again the issue of changing signal amplitudes is mentioned.

Hmm, but Claim 4 points back to Claim 3, which points back to...etc,etc.

If presented with the vorbis code (and possibly an explanation of its operation) and a certain patent, I would find it very hard to make any judgement still, due to the language used in patent documents.

Actually, the way patents work is that to infringe on a patent, you need to infringe on *any* of the claims. However, to infringe on a claim, you have to do something that fits the *totality* of the claim. In this case, I would say that Vorbis doesn't infringe on claim 1, due to the "as a function of signal amplitude changes" (which probably needs to be there because there would likely be prior art for the general case). If Vorbis doesn't infringe on 1, then it automatically doesn't infringe on the others because all the others include 1.

Now, why would they bother making all the other claims dependent on 1 if the fact of not infringing on 1 prevents infringement on the others? The reason is that in probably think 1 may have prior art, in which case, the other claims are still valid (provided there's no prior art on them). Otherwise, prior art on 1 would have totally invalidated the patent. Anyway, the result is still that if Vorbis doesn't infringe on 1, it's safe from 5,214,742.

Very interesting. So, if Vorbis does switching based on envelope band energy level difference, and it can't be interpreted as "signal amplitude change" -based method, then it indeed looks like Vorbis is clear with this patent.

Maybe somebody can elaborate and confirm the switching method Vorbis is based on.

If Vorbis is clear on this, then at least one of the FhG claims is countered succesfully.
Title: Vorbis development, status & patent issues
Post by: Ivan Dimkovic on 2003-09-26 01:05:36
I took a deeper look at the patent - It seems that this patent does not talk about switching criteria at all - they just state 'signal amplitude change' as a condition for switching to the short blocks, which is met in every codec, regardless of the actual switching method - otherwise there would be no point in window switching at all (if energy level is the same).

On page 6 they suggest that signal amplitude change of a given magnitude could be used as a trigger - but they do not state whether this is in time or freq domain - it can be both.

Window switching criteria can be either time-domain energy diff, freq domain energy diff (vorbis is using this, right?), perceptual entropy change (like MP3/AAC) or LPC predction error (Twin VQ, for example) - but I think MP3 and AAC and TwinVQ reference this patent as relevant, and it is in patent portfolio, and they do not use strict "signal amplitude change" in time domain as someone would initially think.  No matter how the blocks are compared (time E, freq E, PE (THR/E), or LPC prediction error),  window switch is always a result of signal amplitude change IMHO.
Title: Vorbis development, status & patent issues
Post by: Ivan Dimkovic on 2003-09-26 01:13:12
I mean - in my opinion, the purpose of the Claim 1  is only to faciliate the need for the window switching from long to short blocks, in case of signal amplitude change - not to elaborate the exact switching method - because the patent itself is about MDCT switched filterbank and not about the switching methods / threshold estimations. That's why they stated "signal amplitude change" only, because this is the reason for block switching in any case - no matter how you look at the signal as I already explained in my previous post.

Elaborate methods for block switching are covered in some later patents from Johnson (M/S psychoacoustic model patent - PE based switching) and Herre/Brandenburg (patent covering time-domain block switching only, dating from 1998 IIRC).  Dolby AC3 uses other time-domain block switching method which might be patented but I am not sure.
Title: Vorbis development, status & patent issues
Post by: ErikS on 2003-09-26 01:48:48
Quote
I mean - in my opinion, the purpose of the Claim 1  is only to faciliate the need for the window switching from long to short blocks, in case of signal amplitude change - not to elaborate the exact switching method - because the patent itself is about MDCT switched filterbank and not about the switching methods / threshold estimations. That's why they stated "signal amplitude change" only, because this is the reason for block switching in any case - no matter how you look at the signal as I already explained in my previous post.

No matter what the purpose of it is, it gives an interesting loop hole out of the patent. Just make sure that the block switching is not a function of amplitude changes, by for example introducing a tiny amount of randomness in the algorithm.

Not that vorbis does this, but I hope they do avoid it somehow... will be interesting to hear the result of that meeting if they address this patent issue seriously.
Title: Vorbis development, status & patent issues
Post by: petracci on 2003-09-26 08:59:44
Quote
I took a deeper look at the patent - It seems that this patent does not talk about switching criteria at all - they just state 'signal amplitude change' as a condition for switching to the short blocks, which is met in every codec, regardless of the actual switching method - otherwise there would be no point in window switching at all (if energy level is the same).


I think this patent is closely related (or follows from) Edler's article "Codierung von Audiosignalen mit überlappender Transformation und adaptiven Fensterfunktionen"

In that article, I see 3 innovations. First, the use of different window lengths for an overlapping transform. Then, the method of creating transition windows. And last, the steering mechanism for the adaptation of the window length. In the article, the steering mechanism is clearly based on time-domain changes in signal amplitude.

For the patent, they probably tried to incorporate as many options  for switching as they could get away with.

Quote
Window switching criteria can be either time-domain energy diff, freq domain energy diff (vorbis is using this, right?), perceptual entropy change (like MP3/AAC) or LPC predction error (Twin VQ, for example) - but I think MP3 and AAC and TwinVQ reference this patent as relevant, and it is in patent portfolio, and they do not use strict "signal amplitude change" in time domain as someone would initially think.  No matter how the blocks are compared (time E, freq E, PE (THR/E), or LPC prediction error),  window switch is always a result of signal amplitude change IMHO.


In the examples you give (so basically all current standards ) I can agree with your last statement.

However, the example I gave previously where you adapt the window lengths based on the actual coding results is different IMO.

E.g. incorporating the rate in the switching selection could lead to situations where you do switch when a high rate is available, but do not switch when a low rate is available, even if signal amplitude change tells you that you should switch. And although those methods might be computationally complex, I do see these as a next step in future codecs.
Title: Vorbis development, status & patent issues
Post by: Ivan Dimkovic on 2003-09-26 09:05:43
Quote
E.g. incorporating the rate in the switching selection could lead to situations where you do switch when a high rate is available, but do not switch when a low rate is available, even if signal amplitude change tells you that you should switch. And although those methods might be computationally complex, I do see these as a next step in future codecs.


Well, that is used in some of the codec implementations - i.e., if the bit reservoir is near 0, and there would be a high bit loss by using short blocks coder can stick to long blocks and, say, activate TNS if such tool is available (although, TNS will be automatically activated for pre-echo clips)

Also, alternative approach would be to measure the TNS gain / savings, to see if there is a real need for short blocks after the TNS, then measure bit cost  and decide whether to switch to short blocks.

Or,  third method would be to code both ways (long and short) - and to measure NMR to see if short blocks yielded in signal quality increase (analysis-by-synthesis)


First two methods are different from suggested approach in the patent, but somehow I think that the "function of signal amplitude change" is always incorporated in them - because any pre-echo measurement deals with short-term amplitude change?  I dunno if it is legally possible to use this as an argument, probably not - as that would be too general for my taste

Third method would use different kind of switching criteria (NMR) but for good pre-echo performance, you would have to have third psychoacosutic model based on very short blocks (like ITU-R BS.1387 / Advanced Model)  in order to screen for time-tomain artifacts.
Title: Vorbis development, status & patent issues
Post by: petracci on 2003-09-26 09:16:51
Quote
I mean - in my opinion, the purpose of the Claim 1  is only to faciliate the need for the window switching from long to short blocks, in case of signal amplitude change - not to elaborate the exact switching method - because the patent itself is about MDCT switched filterbank and not about the switching methods / threshold estimations. That's why they stated "signal amplitude change" only, because this is the reason for block switching in any case - no matter how you look at the signal as I already explained in my previous post.


Next time, let me read both your posts before I try to respond  B)

You argue that the actual patent is only about window switching, and that claim 1 tries to clarify why you should switch (and why this patent is of any use).

My view is that the patent comprises 3 innovations as stated in my previous post:

1 - The window switching for overlapped transforms
2 - The method of obtaining transition windows
3 - The use of (time-domain) signal amplitude changes as a steering mechanism

Quote
Elaborate methods for block switching are covered in some later patents from Johnson (M/S psychoacoustic model patent - PE based switching) and Herre/Brandenburg (patent covering time-domain block switching only, dating from 1998 IIRC).  Dolby AC3 uses other time-domain block switching method which might be patented but I am not sure.


This shows that it is/was allowed to make a patent of different steering mechanisms. Unfortunately, it does not offer us a solution for who is right.

If I am correct in saying that the actual steering mechanism is part of the patent, then different mechanisms are also patentable. If you are correct in saying that there is no claim in the patent on an actual steering mechanism, then there is still room for patenting specific steering mechanisms.

How is this all important for Vorbis? From your explanation of the way a patent works, Vorbis is either safe from the patent (my view) or not (your view).

I can obviously not say that either of us is right, only that I can understand that after reading this particular patent, one might have the idea that one could come up with a time-varying overlapped transform coder that is safe from this patent.

There are many of similar patents out there. For each of these, a detailed study/investigation has to be made to see where the loopholes are. As a programmer/researcher/developer, I would not be bothered by this, but as a company offering its customer "patent-free" solutions, I would make sure that I can provide a basis for my claims.
Title: Vorbis development, status & patent issues
Post by: menno on 2003-09-26 09:19:34
Doesn't Parseval's Theorem say that frequency domain energy is equal to time domain energy?

Even if Vorbis does the energy calculation in the frequency domain on a specific frequency band, there are ways to do the exact same in the time domain, making it a direct function of the amplitude changes. A frequency domain representation is just a different way of presenting the signal, it is still the same signal.

I find the statement "function of changes in signal amplitude" a bit strange. A signal itself is fully defined by it's amplitude changes, meaning that every method of using the signal for the switching is covered, unless you use just 1 sample  . Or am I missing something here?

Menno
Title: Vorbis development, status & patent issues
Post by: Ivan Dimkovic on 2003-09-26 09:21:15
Quote
I can obviously not say that either of us is right, only that I can understand that after reading this particular patent, one might have the idea that one could come up with a time-varying overlapped transform coder that is safe from this patent.


IIRC, on last AES conference in Amsterdam  Dolby presented  variable-length overlapped transform codec that uses MDCT (I think) - the purpose of this codec was to perfectly match the NTSC/PAL timing  frame-by-frame, which wasn't quite possible with today's codecs.  Perfect timing was needed because in case of cut/copy operations small "click" artifacts appeared due to discontinuities.

I can't remember which method they used, because I didn't buy the paper  But whatever method they invented,  they probably filed a patent application for it
Title: Vorbis development, status & patent issues
Post by: petracci on 2003-09-26 09:31:26
Quote
IIRC, on last AES conference in Amsterdam  Dolby presented  variable-length overlapped transform codec that uses MDCT (I think) - the purpose of this codec was to perfectly match the NTSC/PAL timing  frame-by-frame, which wasn't quite possible with today's codecs.  Perfect timing was needed because in case of cut/copy operations small "click" artifacts appeared due to discontinuities.

Is that the 114th convention? I'm searching the proceedings, but am unable to find it. Do you have some more info (e.g. author, session)?
Title: Vorbis development, status & patent issues
Post by: Ivan Dimkovic on 2003-09-26 09:48:01
I think it was:

Quote
5853
Michael J. Smithers,Brett G, Crockett,Louis D. Fielder,
Two methods of coding and delivering ultra-high quality audio are presented. Both methods are video frame synchronous and editable at common video frame rates (23.98, 24, 25, 29.97 and 30 frames per second) without the use of sample rate converters. The first is an ultra-high quality audio coder that exceeds 4.8 on the ITU-R 5 point audio impairment scale at a data-rate of 256 kbps per channel and at up to three generations of encoding/decoding. The second is an enhanced method of video frame synchronous PCM packing. Specifically the problem of transmitting 48 kHz audio in 29.97 Hz frames is examined.
Ultra High Quality, Video Frame Synchronous Audio Coding


But don't take my word for it
Title: Vorbis development, status & patent issues
Post by: petracci on 2003-09-26 09:49:44
Quote
Doesn't Parseval's Theorem say that frequency domain energy is equal to time domain energy?

Yes, but it says nothing about the distribution of energy.

Quote
Even if Vorbis does the energy calculation in the frequency domain on a specific frequency band, there are ways to do the exact same in the time domain, making it a direct function of the amplitude changes. A frequency domain representation is just a different way of presenting the signal, it is still the same signal.


I am not so sure about your first statement (naturally, I agree with your 2nd). I think it is very important in which domain you perform an operation. Take quantization for instance, a key issue in subband/transform coding is to be able to control the spread of quantization noise over the frequency spectrum. There might be ways to accomplish the same in a time-domain representation, but they are -in general- more complex.

If a method for doing this operation in the time-domain was patented, then I thnik that an operation in the frequency domain that obtains the same result is still patentable (i.e. there is an innovation).

Quote
I find the statement "function of changes in signal amplitude" a bit strange. A signal itself is fully defined by it's amplitude changes, meaning that every method of using the signal for the switching is covered, unless you use just 1 sample  . Or am I missing something here?

No, I think that you're on the spot.

First of all, it is my view that the patent is (a.o.t). about changes in time-domain signal amplitude.

Secondly, there are switching algorithms based on (combinations of) rate, distortion and coding delay imaginable (and implemented) that obtain different switching results for different constraints.

What I am trying to say is that a switching mechanism based on a "function of changes in signal amplitude" will always give you the same switching result, independent of desired quality/bit rate. A function of (combinations of) rate, distortion and coding delay might give you different switching results each time a constraint is changed, even if the signal stays the same.
Title: Vorbis development, status & patent issues
Post by: petracci on 2003-09-26 09:57:19
Quote
I think it was:

Quote

5853
Michael J. Smithers,Brett G, Crockett,Louis D. Fielder,
Two methods of coding and delivering ultra-high quality audio are presented. Both methods are video frame synchronous and editable at common video frame rates (23.98, 24, 25, 29.97 and 30 frames per second) without the use of sample rate converters. The first is an ultra-high quality audio coder that exceeds 4.8 on the ITU-R 5 point audio impairment scale at a data-rate of 256 kbps per channel and at up to three generations of encoding/decoding. The second is an enhanced method of video frame synchronous PCM packing. Specifically the problem of transmitting 48 kHz audio in 29.97 Hz frames is examined.
Ultra High Quality, Video Frame Synchronous Audio Coding


But don't take my word for it 

That's the one, very interesting, I completely missed that one.

It does look like a different switching scheme, since they change the amount of overlap.
Title: Vorbis development, status & patent issues
Post by: Ivan Dimkovic on 2003-09-26 10:04:13
I think we got into one very serous discussion right now,  because this patent is applicable to many other codecs, some of them - not that open

It would be very interesting for the audio coding society to see what is the real influence of this patent to MDCT window switched codecs - I think the best way would be to call Mr. Edler to participiate as he is the principal inventor of the window-switched filterbank.

If patent proves to be applicable to Vorbis/WMA/...  it will be quite problematic to avoid it in any further "free" codec.  Otherwise, it would be a clear sign that it is possible to write audio coding-decoding system that works in MDCT domain without infringing some of the "unavoidable" patents.
Title: Vorbis development, status & patent issues
Post by: petracci on 2003-09-26 10:12:44
Quote
I think we got into one very serous discussion right now,  because this patent is applicable to many other codecs, some of them - not that open

Yes, or I'd rather say that is might be applicable (and probably is).

Quote
It would be very interesting for the audio coding society to see what is the real influence of this patent to MDCT window switched codecs - I think the best way would be to call Mr. Edler to participiate as he is the principal inventor of the window-switched filterbank.


I will see Mr. Edler end of november, but I could also send a mail. I know he's rather busy and he might mot have time to answer before november anyway.

Quote
If patent proves to be applicable to Vorbis/WMA/...  it will be quite problematic to avoid it in any further "free" codec.   Otherwise, it would be a clear sign that it is possible to write audio coding-decoding system that works in MDCT domain without infringing some of the "unavoidable" patents.


Yes, and it would be very valuable to have a list of these "unavoidable" patents and study their possible loopholes. But I assume thatthey have this list at Vorbis development  ?

As for WMA, I have the idea that they do something different than window switching. See patent US6115689.
Title: Vorbis development, status & patent issues
Post by: Ivan Dimkovic on 2003-09-26 10:38:41
http://cvs.sourceforge.net/viewcvs.py/ffmp...=1.18&view=auto (http://cvs.sourceforge.net/viewcvs.py/ffmpeg/ffmpeg/libavcodec/wmadec.c?rev=1.18&view=auto)

Code took from the relevant .c file - please see copyright note for the project (link above)!:

Quote
/* build the window : we ensure that when the windows overlap
       their squared sum is always 1 (MDCT reconstruction rule) */

    /* XXX: merge with output */
    {
        int i, next_block_len, block_len, prev_block_len, n;
        float *wptr;

        block_len = s->block_len;
        prev_block_len = 1 << s->prev_block_len_bits;
        next_block_len = 1 << s->next_block_len_bits;

        /* right part */
        wptr = window + block_len;
        if (block_len <= next_block_len) {
            for(i=0;i<block_len;i++)
                *wptr++ = s->windows[bsize];
        } else {
            /* overlap */
            n = (block_len / 2) - (next_block_len / 2);
            for(i=0;i<n;i++)
                *wptr++ = 1.0;
            for(i=0;i<next_block_len;i++)
                *wptr++ = s->windows[s->frame_len_bits - s->next_block_len_bits];
            for(i=0;i<n;i++)
                *wptr++ = 0.0;
        }

        /* left part */
        wptr = window + block_len;
        if (block_len <= prev_block_len) {
            for(i=0;i<block_len;i++)
                *--wptr = s->windows[bsize];
        } else {
            /* overlap */
            n = (block_len / 2) - (prev_block_len / 2);
            for(i=0;i<n;i++)
                *--wptr = 1.0;
            for(i=0;i<prev_block_len;i++)
                *--wptr = s->windows[s->frame_len_bits - s->prev_block_len_bits];
            for(i=0;i<n;i++)
                *--wptr = 0.0;
        }
    }


I dunno about the patent - will take some time to analyse it carefully, but the provided ffmpeg code that is claimed to decode WMA smells like a MDCT block-switched coder with overlapped sine windows (as it could be seen in the code).
Title: Vorbis development, status & patent issues
Post by: petracci on 2003-09-26 10:49:51
Quote
I dunno about the patent - will take some time to analyse it carefully, but the provided ffmpeg code that is claimed to decode WMA smells like a MDCT block-switched coder with overlapped sine windows (as it could be seen in the code).


Seems that you're correct. But will the ffmpeg decoder also handle WMA9-coded fragments?
Title: Vorbis development, status & patent issues
Post by: Ivan Dimkovic on 2003-09-26 10:53:11
Actually, I never tried that FFMPEG code, so I am not sure.  But considering the fact that MS announced plans to open WMV/WMA specifications, I am sure they probably reworked all of the code to avoid any legal problems they might have.


It is also funny how FFMPEG used some of the Vorbis code for decoding WMA streams
Title: Vorbis development, status & patent issues
Post by: petracci on 2003-09-26 11:01:05
Quote
Actually, I never tried that FFMPEG code, so I am not sure.  But considering the fact that MS announced plans to open WMV/WMA specifications, I am sure they probably reworked all of the code to avoid any legal problems they might have.


If they paid for licensing that patent on window-switching (or any other patent which they use), would that allow them to open up the specs?

Quote
It is also funny how FFMPEG used some of the Vorbis code for decoding WMA streams


The LSP-to-curve code? I wonder if MS patented the idea of floor coding in general or only a specific way of coding the masking curve. Again a question for Vorbis (and probably a patent) that they should consider (or have considered, in which case it would be nice to know about it).
Title: Vorbis development, status & patent issues
Post by: Ivan Dimkovic on 2003-09-26 11:06:43
Quote
If they paid for licensing that patent on window-switching (or any other patent which they use), would that allow them to open up the specs?


Of course  But...  well,  I think further elaborate on this is just not for public forum....  Discussion about who paid and who did not paid for somethign is somewhat tricky, and I feel that I am in no legal posistion to comment on that

Quote
The LSP-to-curve code? I wonder if MS patented the idea of floor coding in general or only a specific way of coding the masking curve. Again a question for Vorbis (and probably a patent) that they should consider (or have considered, in which case it would be nice to know about it).


That is also interesting,  would be worth trying digging in all NTT and Microsoft patents regarding this, since they are the only companies dealing with VQ / floor coding.
Title: Vorbis development, status & patent issues
Post by: DSPguru on 2003-09-26 11:15:45
Quote
Actually, I never tried that FFMPEG code, so I am not sure.  But considering the fact that MS announced plans to open WMV/WMA specifications, I am sure they probably reworked all of the code to avoid any legal problems they might have.

recently, the official ffmpeg homepage (http://ffmpeg.sourceforge.net/) had been closed to protest against software patents. so, they might suffer from legal problems.

regarding wma9,
afaik, it isn't supported by wmadec.c. only older versions, pre-wma9, are supported (0x160 & 0x161, that is, wmav1 & wmav2)


[span style='font-size:8pt;line-height:100%']edit : typo[/span]
Title: Vorbis development, status & patent issues
Post by: Ivan Dimkovic on 2003-09-26 11:21:28
Quote
recently, the official ffmpeg homepage had been closed to protest against software patents. so, they might suffer from legal problems


Actually, none of these patents are "software" patents (common misconception), and they are registered in USA, Japan and all EU countries more than 10 years ago - so they were "valid" even before EU adopted policy of accepting software patents.
Title: Vorbis development, status & patent issues
Post by: Ivan Dimkovic on 2003-09-26 12:01:31
Quote
e.g. if the complete technological details were publicly available more than 20 years ago, then this technology is patent free. If there was a patent before, it has now expired. If there was a (same, similar or encompassing) patent filed more recently, then it doesn't cover this technology.


The thing is,  which is core of this discussion - is that adaptive window switched MDCT filterbanks didn't exist 20 years ago - they were result of work of H.Malvar, J. Princen, A. Bradley and, finally, B. Edler (dynamic switching)  in late 80's.
Title: Vorbis development, status & patent issues
Post by: petracci on 2003-09-26 12:18:05
Quote
Ivan Dimkovic
That is also interesting,  would be worth trying digging in all NTT and Microsoft patents regarding this, since they are the only companies dealing with VQ / floor coding.


yes, but I'm not going to do that 

But seriously, there must be so many patents out there that potentially cover aspects of the vorbis codec. I can see that it would cost an immense amount of time (and probably money) to investigate these all, but that does not free one from the responsability for providing facts to support one's claims.

Quote
2Bdecided
But this doesn't mean that there's no such thing as patent free.

I do not claim otherwise. But I would like to see evidence from Vorbis that this is the case.

If a respected developer/researcher like Ivan is not certain whether a single patent applies to Vorbis (Ivan, if I misinterpret your postings, please correct me), how can a company be expected to obtain a view on this? Should they just accept the claim?
Title: Vorbis development, status & patent issues
Post by: Ivan Dimkovic on 2003-09-26 12:34:46
Quote
If a respected developer/researcher like Ivan is not certain whether a single patent applies to Vorbis (Ivan, if I misinterpret your postings, please correct me), how can a company be expected to obtain a view on this? Should they just accept the claim?


You are right - I am not sure,  of course - I did not take claims from people from big companies for granted,  I looked at the patent - and I disclosed my thoughts here.

Unfortunately, as it looks to me - this patent is very hard to avoid,  and, like everyone else on this forum I guess, I would really like to see some kind of official Xiph explanation how they manage to avoid this patent in their code.

MP3 itself does not use time-domain energy diff switching method, it does not even use straight MDCT, but still - this patent is in the patent pool... so I dunno...
Title: Vorbis development, status & patent issues
Post by: petracci on 2003-09-26 14:18:20
Quote
You are right - I am not sure,  of course - I did not take claims from people from big companies for granted,  I looked at the patent - and I disclosed my thoughts here.


Well, at least I got that part right 

Quote
Unfortunately, as it looks to me - this patent is very hard to avoid,  and, like everyone else on this forum I guess, I would really like to see some kind of official Xiph explanation how they manage to avoid this patent in their code.


Yes, I would like that as well. But I do think that c_haese has a point here when talking about the validity of patents. Even if Xiph would come with an explanation saying "we avoid patent X because it claims method Y while we use method Z", somebody such as yourself could come in and say "I think that patent X is not about method Y but about method A. Within method A, a method is used that could be method Y but also method Z". The accepted way of determining who is right in the case of patents would be to go to court.

So all Xiph could say is "we think we avoid patents A,B,... because this and this"

Which is off course better that the current situation.
Title: Vorbis development, status & patent issues
Post by: danchr on 2003-09-27 11:09:47
Quote
Quote
Actually, I never tried that FFMPEG code, so I am not sure.  But considering the fact that MS announced plans to open WMV/WMA specifications, I am sure they probably reworked all of the code to avoid any legal problems they might have.

recently, the official ffmpeg homepage (http://ffmpeg.sourceforge.net/) had been closed to protest against software patents. so, they might suffer from legal problems.

FFmpeg already uses several patented techniques. They have MP2 and MP3 decoders, MPEG-{1,2,4} encoders and decoders, an H.264 decoder and more. So their situation couldn't get much worse; it's already nearly impossible to use FFmpeg commercially without paying someone. The entire project goal seems to be to have as many as possible codecs with a complete disregard to patents  You may already have known this, though...

Just my 0,02kr. (no € yet). Very interesting disussion, BTW!
Title: Vorbis development, status & patent issues
Post by: c_haese on 2003-09-29 22:17:23
Okay, let's get back to the scientific problem at hand. The patent we're discussing is about window switching, and specifically the method used to determine the window length. After digging through the code for not very long, that task seems to be performed by _ve_envelope_search, which in turn calls on _ve_amp. The comment in front of _ve_amp says this:

/* fairly straight threshhold-by-band based until we find something
  that works better and isn't patented. */

(envelope.c, line 87, current CVS)

At the very least this tells me that Monty is aware of the patent problem surrounding the window switching and is employing a specific method to avoid patents. That's probably as official a position as you'll get, at least until the monthly meeting.

Hope this helps,

Carsten Haese.

Edit: typo fixes
Title: Vorbis development, status & patent issues
Post by: menno on 2003-09-30 14:03:09
Quote
After digging through the code for not very long, that task seems to be performed by _ve_envelope_search, which in turn calls on _ve_amp. The comment in front of _ve_amp says this:

/* fairly straight threshhold-by-band based until we find something
   that works better and isn't patented. */

Calculating energy is a function of signal amplitude. Whether it's done in time or frequency domain doesn't matter, as it means exactly the same (I explained that before).

The way I understood it, Vorbis tries to work around this patent by not doing something that is before the "improvement" part of the first claim.

Menno
Title: Vorbis development, status & patent issues
Post by: Ivan Dimkovic on 2003-09-30 23:09:02
Ok, for those with lmiited ability to read:

Instead making analogies,  calling someone good, evil, poor, innocent, etc

Consider this like a pure technical question called:

[span style='font-size:21pt;line-height:100%']How can you avoid US Patent #5,214,742 in a MDCT window-switched codec?[/span]

And -

- Forget the codec name
- Forget the quantization algorithm (not covered by patent)
- Forget the coding algorithm (not covered by patent)

JUST FILTERBANK and window switching model...

So - we are getting down to elementary technical level, ok?

I hope that we can get back to meaningful discussion which could have some scientific importance.
Title: Vorbis development, status & patent issues
Post by: JohnV on 2003-10-01 09:00:17
Thread re-arranged. This thread is now only for technical discussion.
All non-technical posts regarding this issue must go here:
Vorbis development, status & patent issues PART 1 - NON-technical discussion (http://www.hydrogenaudio.org/forums/index.php?showtopic=13686)
Clearly non-technical posts in this thread will be either moved or deleted.

Currently the Vorbis patent issue covers these threads:
Vorbis development, status & patent issues PART 1 - NON-technical discussion (http://www.hydrogenaudio.org/forums/index.php?showtopic=13686)
Vorbis development, status & patent issues PART 2 - Technical discussion (This thread) (http://www.hydrogenaudio.org/forums/index.php?showtopic=13531)
Title: Vorbis development, status & patent issues
Post by: jmvalin on 2003-10-01 23:26:39
Quote
Consider this like a pure technical question called:

How can you avoid US Patent #5,214,742 in a MDCT window-switched codec?

...

So - we are getting down to elementary technical level, ok?

I hope that we can get back to meaningful discussion which could have some scientific importance.

The only technical answer to this question is in Monty's code (envelope.c pointed to by c_haese). Anything more (debating the exact meaning of the words in the patents) is not a technical/scientific discussion but rather a legal one, which I don't think can be answered (without just stating opinions) by anyone on HA (including me). That is, unless you're a patent attorney?
Title: Vorbis development, status & patent issues
Post by: Ivan Dimkovic on 2003-10-02 09:21:50
Quote
Quote
Consider this like a pure technical question called:

How can you avoid US Patent #5,214,742 in a MDCT window-switched codec?

...

So - we are getting down to elementary technical level, ok?

I hope that we can get back to meaningful discussion which could have some scientific importance.

The only technical answer to this question is in Monty's code (envelope.c pointed to by c_haese). Anything more (debating the exact meaning of the words in the patents) is not a technical/scientific discussion but rather a legal one, which I don't think can be answered (without just stating opinions) by anyone on HA (including me). That is, unless you're a patent attorney?

Ah ... so Monty speaks through source code only 

Well, the code does not explain how they avoided patent. In fact,  cheching the spectral envelope level is analog to checking signal amplitude level in my books (just in frequency instead of time domain) - However it does not violate, one other patent where the change in perceptual entropy (PE) is proposed as a switching mechanism  - but the thing with window-switched filterbanks is still in place, IMHO.

Furthermore, this might not be the reason why they claim they avoided the patent at all - but for all of that, we need to hear technical opinion from someone who actually invented Vorbis, because he is the only one who knows how did they avoid patents, right?

Like Danchr said - that is purely a technical discussion, because he used technical (his digital signal processing proficiency), not legal (employing DSP experts and DSP and patent expers + hell load of lawyers), means to avoid the patents.
Title: Vorbis development, status & patent issues
Post by: JohnV on 2003-10-05 23:38:22
Ok, I asked Xiph's opinion about this specific issue discussed in this thread at Xiph's monthly meeting which is open to public. Here was the answer (the whole Xiphmeeting log can be read here (http://xiph.org/~jack/200310.txt)):
Quote
<JohnV> well.. I've gathered here the technical talk in HydrogenAudio regarding speculations whether US 5,214,742 can be avoided in a MDCT codec with window switching: http://www.hydrogenaudio.org/forums/index....showtopic=13531 (http://www.hydrogenaudio.org/forums/index.php?showtopic=13531)
<xiphmont> JohnV: that patent is not about windows or window switching, it's about the specific method o deciding when to switch.
<JohnV> xiphmont: well, the question is, can it be avoided in a codec which does window switching..
<purple_haese> JohnV: Yes, by using a different method for deciding when to switch.
<JohnV> purple_haese: does Vorbis use "different method"?
<purple_haese> JohnV: xiphmont seems to think so.
<JohnV> seems to think so?
<xiphmont> JohnV: IANAL [I Am Not A Lawyer]
<JohnV> xiphmont: but you base it on what exactly? You are not a lawyer but what is this thinking based on?
<purple_haese> JohnV: In cases you haven't noticed,  the meeting has moved away from the patent discussion. After consultation with the lawyer, we will disclose as much as we possibly can.


Not much explanation there, but later Monty said to me this (outside the meeting): "The patents describe mp3.  We have a different transform path.  For many reasons they don;t pply, but I'm not allowed to say that unless I'm a lawyer."

Xiph is planning somekind of response after consulting with lawyer, but I don't know if it brings any light to this issue.
Title: Vorbis development, status & patent issues
Post by: Ivan Dimkovic on 2003-10-06 08:30:55
All in all, this is how I perceive the picture... sorta "thinking loud":

Xiph - "We claim Ogg Vorbis is patent free (on the website)"

Q1: "Can you guarantee you are free of patents"

Xiph - "No, nobody can - and you need a expensive lawyer opinion for that"

Q2: "Ok, so how can you claim  "patent free" on the website without applying the same logic?"

Xiph - "We are about to define "patent free" after the meeting"  (analogy with RMS goes here... )

(still, while not defined what actually is, claim "patent free" is key marketing argument for years and the way to disqualify some better codecs as "codecs with patent issues" like somebody said on this forum - see the problem?)

<personal opinion> Maybe it is better to call Vorbis "license free" or "royalty free" since both statements are true even if some patents are infringed  </personal opinion>

Q3: "What is the Xiph's stand on US 5,214,742?"

Xiph: "We cannot comment, you need a professional lawyer opinion"

Q4: "But in-depth technical discussion is presented on HA... c"

Xiph: "We said enough... case closed... meeting moves to... next topic"


IMHO,  one thing is somewhat unclear - Xiph does not want to go into any technical discussion about Vorbis implementation and current patent situation in US and EU,  and especially couple of patents which raise eyebrows - some kind of "no - patent describes THIS WAY, and we did THAT WAY" discussion would be welcome - but unfortunately hard to expect.  I understand that stand, probably every Monty's word has very big legal weight since he is the leader and founder of Xiph - and he probably likes to hear lawyer's opinion before he says something about Ogg in public (but somehow I think technical aspects are of no lawyer's concern)

So, let's wait for the new definition of "patent free" in Vorbis - and, maybe some official lawyer's opinion if it is allowed to be said in public
Title: Vorbis development, status & patent issues
Post by: jmvalin on 2003-10-06 20:11:19
Quote
Ok, I asked Xiph's opinion about this specific issue discussed in this thread at Xiph's monthly meeting which is open to public. Here was the answer (the whole Xiphmeeting log can be read here (http://xiph.org/~jack/200310.txt)):

JohnV, your quote is a bit misleading as it doesn't show that the discussion was already over (after we agreed that we should prepare a statement) for a while and at that point, you were just adding noise to the meeting (for those who haven't read the logs, the comments in the quote were interleaved with the "on topic stuff").
Title: Vorbis development, status & patent issues
Post by: JohnV on 2003-10-06 21:25:18
Quote
Quote
Ok, I asked Xiph's opinion about this specific issue discussed in this thread at Xiph's monthly meeting which is open to public. Here was the answer (the whole Xiphmeeting log can be read here (http://xiph.org/~jack/200310.txt)):

JohnV, your quote is a bit misleading as it doesn't show that the discussion was already over (after we agreed that we should prepare a statement) for a while and at that point, you were just adding noise to the meeting (for those who haven't read the logs, the comments in the quote were interleaved with the "on topic stuff").

Discussion already over? In the logs one can see yourself talking about the patent issue with PsyQ (Ivan) in the same minute as I started! And where in the logs it said the patent talk ended? And why did it end so rapidly anyway, before people had really time to ask any questions?
I was just adding noise to the meeting by bringing up this HA thread?? Jeez?? You guys are just incredible...

I urge everybody to read the logs http://xiph.org/~jack/200310.txt (http://xiph.org/~jack/200310.txt) and consider themselves if what you said is true...
In case someone doesn't bother I just directly copy lines here which happened before my first comment. Timestamps are from the Xiph log.
Quote
17:24 < xiphmont> Well, I'd have to be the technical side of making such an opinion wit the lawyer.
17:24 < purple_haese> It doesn't have to be elaborate, and it would be a clear sign of good will.
17:24 < derf_> In fact, you're potentially liable for up to triple damages just for reading the thing without consulting your lawyer, for "willful infringement".
17:25 < jack> derf ha sa point here.
17:25 < purple_haese> Yikes.
17:25 < PsyQ> derf: well, how is anyone who is not a lawyer qualified to call something "patent free"?
17:25 < jack> let me ask the lawyer
17:25 < jmspeex> derf_: single/triple damage doesn't change a thing in our case.
17:25 < purple_haese> Well, then the best we can do, unfortunately, is to explain why we can't make specific statements about specific patents.
17:26 < jmspeex> PsyQ: we define "patent-free". It's like free software, RMS decides what qualifies as "free software"
17:26 < jack> purple_haese: that may be the case.  anyway, i'll send an email to tom and we'll figure out where to go from there.
17:26 < xiphmont> yes, we need some sort of statement.
17:27 < PsyQ> jmspeex: free software does not anything to do with "patent free", so I'd leave RMS out of this discussion
17:27 < jack> ok..  stan, you had some changes to libao you wanted to discuss?
17:27 < purple_haese> Businesses that are interested in Vorbis can always take the money they save on licensing and put part of it toward their own patent opinion, or buy some liability insurance
17:28 < PsyQ> ok - so you defined "patent free" as ?  I guess free of your own patents?
17:28 < jmspeex> PsyQ: What I mean is that when the FSF talks about "free software", they also define what they mean exactly by "free software". We should do the same with "patent-free".
17:28 < volsung> Should I jump in now? 
17:28 -!- mackstann [~death@12-217-123-219.client.mchsi.com] has joined #xiphmeet
17:28 < JohnV> well.. I've gathered here the technical talk in HydrogenAudio regarding speculations whether US 5,214,742 can be avoided in a MDCT codec with window switching: http://www.hydrogenaudio.org/forums/index....showtopic=13531 (http://www.hydrogenaudio.org/forums/index.php?showtopic=13531)


The patent discussion started at 17:14, and you are saying that at 17:28 my comment was already off-topic noise, also considering the direct quote from the discussion above? Nice... Frankly I thought that this topic would have been given more emphasis. I thought I was being polite not to shoot my comment right a way, rather give Xiph some time to first say its general view about the subject. I was not asking or wanting any round statements from a lawyer to my comment, rather some coder opinion and brief technical explanation about the principle of avoiding this patent in code in coder's point of view. Obviously Xiph's tactics was to get rid of this topic as soon as possible before the real questions come.
Title: Vorbis development, status & patent issues
Post by: jmvalin on 2003-10-07 03:17:26
Quote
Discussion already over? In the logs one can see yourself talking about the patent issue with PsyQ (Ivan) in the same minute as I started! And where in the logs it said the patent talk ended? And why did it end so rapidly anyway, before people had really time to ask any questions?
I was just adding noise to the meeting by bringing up this HA thread?? Jeez?? You guys are just incredible...

I said you were adding noise to the meeting because you were the only one left that was talking about that at that point in the meeting (yes, the patent talk ended at the time people started talking about the next point). Besides, it wasn't worth debating much until we at least come up with a draft statement about the patent status. Believe me, I'm one of those that really want to have that. I'll save me tons of explaination.

BTW, when I said you post was misleading, I just meant that by not using "..." (or similar), you made it look like you quoted verbatim, while in fact the comments were more scattered.
Title: Vorbis development, status & patent issues
Post by: JohnV on 2003-10-07 04:54:02
Quote
I said you were adding noise to the meeting because you were the only one left that was talking about that at that point in the meeting (yes, the patent talk ended at the time people started talking about the next point).

I was the only one who was talking about that? Monty's and Haese's comments just magically appeared on the log. I see. I shouldn't have answered to Monty or Haese because other Xiph members pushed the discussion away from the topic at hand.

I'd rather say some other people added "noise", because there was a discussion going on between me, Monty and Haese, and it started by me when everybody was still talking about the patent issue. You can clearly see that in the logs. And again, I was not asking any "statements" about what is meant with "patent free". I was asking for coder opinion, even on the general principle level about the issue covered in this thread (even forgetting Vorbis, and talking totally in general level, but I was made to shut up there by Xiph before I had a chance to say anything further).

Thank you for letting me know that I only added noise, since after all, this is no important issue at all, right, and I'm just a troll who was adding noise there, when there was "much more important issues" to cover. At least I now know your position what comes to me..

This all makes me wonder why I ever wasted my time bringing up Vorbis quality issues when 1.0 was in the makings, or why I bother keeping up Vorbis forums here, or why I bother asking clarifications to an issue, which might in the end add hughly positive impact on Vorbis. Why should a troll like me do anything for you guys.
Title: Vorbis development, status & patent issues
Post by: jmvalin on 2003-10-07 06:40:16
Quote
I was the only one who was talking about that? Monty's and Haese's comments just magically appeared on the log. I see. I shouldn't have answered to Monty or Haese because other Xiph members pushed the discussion away from the topic at hand.


OK, first my main point was not the noise vs. not noise issue, but just the fact that the way you quoted was misleading. Can you at least acknowledge that?

Quote
I'd rather say some other people added "noise", because there was a discussion going on between me, Monty and Haese, and it started by me when everybody was still talking about the patent issue. You can clearly see that in the logs. And again, I was not asking any "statements" about what is meant with "patent free". I was asking for coder opinion, even on the general principle level about the issue covered in this thread (even forgetting Vorbis, and talking totally in general level, but I was made to shut up there by Xiph before I had a chance to say anything further).


OK, so you were "made to shut up by Xiph". Everyone knows that Xiph is a large, powerful organization with the power to silence people, right?

Quote
Thank you for letting me know that I only added noise, since after all, this is no important issue at all, right, and I'm just a troll who was adding noise there, when there was "much more important issues" to cover. At least I now know your position what comes to me..


I probably want this statement more than you do and probably would have liked to discuss it a bit further... *However*, I realize that going deeper into topics in this kind of *general* meeting just makes the meeting last forever (this one was already 1.5 hours long). That's why we can't stay too long on something. Don't worry, you'll have plenty of time to comment once we at least have something to show.

Quote
This all makes me wonder why I ever wasted my time bringing up Vorbis quality issues when 1.0 was in the makings, or why I bother keeping up Vorbis forums here, or why I bother asking clarifications to an issue, which might in the end add hughly positive impact on Vorbis. Why should a troll like me do anything for you guys.


Don't cry, we love you JohnV 
Title: Vorbis development, status & patent issues
Post by: JohnV on 2003-10-07 07:09:34
Quote
OK, first my main point was not the noise vs. not noise issue, but just the fact that the way you quoted was misleading. Can you at least acknowledge that?

It was not misleading. I included all the lines which were relevant to issue I brought up and excluded non-relevant lines which had nothing to do with the issue I brought up.

In that above message I said this: "Ok, I asked Xiph's opinion about this specific issue discussed in this thread at Xiph's monthly meeting which is open to public. Here was the answer (the whole Xiphmeeting log can be read here):"

I brought up the issue when the patent discussion was still going on, and quoted the lines which followed from it, excluding Volsung's "off-topic" lines which pushed the discussion away from the topic and had nothing to do with answers to this issue, so if anybody was bringing noise, it was Volsung. I never claimed the quote in this (http://www.hydrogenaudio.org/forums/index.php?act=ST&f=8&t=13531&hl=&view=findpost&p=141103) message was full irc log with all the non-issue lines, but I linked to the full log anyway. But the quote in my message here (http://www.hydrogenaudio.org/forums/index.php?act=ST&f=8&t=13531&hl=&view=findpost&p=141415) is a direct copy with all the lines and timestamps from a certain section of the log, and it shows the patent discussion was still going on.

Quote
OK, so you were "made to shut up by Xiph". Everyone knows that Xiph is a large, powerful organization with the power to silence people, right?
No, but I was clearly said the discussion is over, and I respected that, since it was the "Monthly Xiph Meeting, open to public".
Title: Vorbis development, status & patent issues
Post by: Ivan Dimkovic on 2003-10-07 08:06:47
Like I said - if somebody is so sure he avoided patents, and he is the designer of the method which is claimed to be patent free in the same time,  he could certainly say something like:

"No, US Patent XXXXXXX  claims that YYYY is done in THIS way", and our code/product is doing something in THAT way - take a look at ZZZZ.C and page N of the US XXXXXX, thus in my (not professional) opinion ZZZZ.C is not violating the patent.

The issue is pushed to the very limits on "question" side,  and the "answer" side didn't do anything to make issue more clear.
Title: Vorbis development, status & patent issues
Post by: PatchWorKs on 2003-10-07 08:34:01
I don't want to be boring, but i have to say it again:

US PATENTS ARE NOT WORLD PATENTS !!!     

If Vorbis is illegal in US is an US problem.
Sincerly i don't care; I just wanna remember all of you that HA is mostly composed by European users. 

Some interesting articles follows:

Recent EFF Legal Cases and Efforts (http://www.eff.org/Legal/recent_legal.html)

FFII: Software Patents in Europe (http://swpat.ffii.org/)

...and we won the 1st battle: Parliament Accepts Petitions Against Software Patents (http://swpat.ffii.org/journal/03/peti1001/index.en.html) 

(note: would this mean that Xiph should move to EU ?)
Title: Vorbis development, status & patent issues
Post by: Dibrom on 2003-10-07 08:43:19
Quote
I don't want to be boring, but i have to say it again:

US PATENTS ARE NOT WORLD PATENTS !!!    

If Vorbis is illegal in US is an US problem.
Sincerly i don't care; I just wanna remember all of you that HA is mostly composed by European users. 

Not only is this off-topic to this thread, but it's irrelevant to the entire discussion.

The issue has never been about US patents being some universal (or even really patents at an essential level themselves), it has been about the meaning behind a claim made by Xiph and about the status of Vorbis technology in relation to other technology.

Please do not continue this off-topic and irrelevant discussion here.
Title: Vorbis development, status & patent issues
Post by: sthayashi on 2003-10-07 14:22:02
JohnV,

It seems to me that Monty's unofficial position on this matter is that patent 5,214,742 is not about Window Switching, but a specific method on when to switch (according to his IRC statement).  To answer the question that you asked on IRC, if a window-switching codec CAN avoid infringment with this patent, then Vorbis is doing so.

The problem is that the wording of that part of the patent is a little vague. I think even you are willing to concede that point. Vorbis doesn't use signal amplitude changes directly to control the window switching.  But since I would dare say that all signals are defined by their amplitude changes, Vorbis is at the very least INDIRECTLY using signal amplitude changes.

So there are two different ways of interpreting this patent, one of them shows Vorbis to be infringing.  Which one is right?  No one is saying officially because no one wants to lose credibility if they're wrong.  I'm betting that Xiph is staying away from it, because they stand to lose no matter how it's cut.

Incidentally, I found two other patents that were interesting:
Title: Vorbis development, status & patent issues
Post by: Ivan Dimkovic on 2003-10-07 14:36:54
Quote
I don't want to be boring, but i have to say it again:

US PATENTS ARE NOT WORLD PATENTS !!!    

If Vorbis is illegal in US is an US problem.
Sincerly i don't care; I just wanna remember all of you that HA is mostly composed by European users.  

Some interesting articles follows:

Recent EFF Legal Cases and Efforts (http://www.eff.org/Legal/recent_legal.html)

FFII: Software Patents in Europe (http://swpat.ffii.org/)

...and we won the 1st battle: Parliament Accepts Petitions Against Software Patents (http://swpat.ffii.org/journal/03/peti1001/index.en.html) 

(note: would this mean that Xiph should move to EU ?)

Yes you are boring - because you do not seem to read whole thread before posting...

Once again,

For example check the US#5,214,742  status:

http://ep.espacenet.com/ (http://ep.espacenet.com/)  (US5214742)

Equivalent patents:

CA2026441,  DD292791,  DE3902948,  EP0414838 (WO9009063),  B1, ES2045902T,  FI101252B, HK55296, HU56473, JP3226537B2, JP3503829T, KR140877, TR24444,  WO9009063

So this patent (like almost all other patents related to audio coding)  is registered worldwide, including USA, EU, Japan, Korea etc.. in 1992.

Once again: audio coding patents ARE NOT SOFTWARE PATENTS (also, they are registered worldwide) and I would like to stay out of that discussion when we discuss implementation issues of particular audio-coding /decoding system
Title: Vorbis development, status & patent issues
Post by: Ivan Dimkovic on 2003-10-07 15:02:27
Quote
JohnV,

It seems to me that Monty's unofficial position on this matter is that patent 5,214,742 is not about Window Switching, but a specific method on when to switch (according to his IRC statement).  To answer the question that you asked on IRC, if a window-switching codec CAN avoid infringment with this patent, then Vorbis is doing so.

The problem is that the wording of that part of the patent is a little vague. I think even you are willing to concede that point. Vorbis doesn't use signal amplitude changes directly to control the window switching.  But since I would dare say that all signals are defined by their amplitude changes, Vorbis is at the very least INDIRECTLY using signal amplitude changes.

So there are two different ways of interpreting this patent, one of them shows Vorbis to be infringing.  Which one is right?  No one is saying officially because no one wants to lose credibility if they're wrong.  I'm betting that Xiph is staying away from it, because they stand to lose no matter how it's cut.

Incidentally, I found two other patents that were interesting:
  • US5,321,729 - which appears to ALSO be a patent for Window Switching... I'm not sure since I find reading patent filings is quite painful.



  • US5,848,391 - which is completely unrelated to Vorbis, but I was wondering whether Musepack infringed on this (I don't know the details of MPC).

Quote
It seems to me that Monty's unofficial position on this matter is that patent 5,214,742 is not about Window Switching, but a specific method on when to switch (according to his IRC statement). To answer the question that you asked on IRC, if a window-switching codec CAN avoid infringment with this patent, then Vorbis is doing so.


According to my analysis of claims patent is basically claiming this:

1. Improvement consisting of selecting of window length depending on signal amplitude change

2. Window length is a function of signal amplitude change

3. Length of the window is small for large changes, and big for small changes

4, 5, 6 - deal with the forming of transition "overlap/add" windows

7. Tells the spacing between windows changes depending on the amp. chng.

8. Changes are in time

9. Signals are audio signals

Quote
The problem is that the wording of that part of the patent is a little vague. I think even you are willing to concede that point. Vorbis doesn't use signal amplitude changes directly to control the window switching. But since I would dare say that all signals are defined by their amplitude changes, Vorbis is at the very least INDIRECTLY using signal amplitude changes.


Well, defending Xiph position can be done on two basis:

#1 Attacking claim 1 with argument that vorbis do not code spectrum, but residual

#2 Attacking claim 1 with argument that switching criterion is different from "signal amplitude change"


Personally, I think argument #1 can't be very helpful, because the final result before IMDCT in decoder is actual MDCT signal - which is overlapped and added, so the signal is "coded" no matter how the coding representation is done in the encoder/bitstream (LPC+VQ or direct scalar quantization of the coefficients, like in MP3/AAC) - and the patent does not go into the coding implementation at all.

Argument #2 is more serious - and the validity of it is only subject to determining if Parseval's theorem applies - i.e., is checking envelope level change in threshold bands equal to "signal amplitude change"... but we have another problem - patent does not specify whether "signal amplitude change" is in time or frequency domain, or how should checking/triggering be done at all!

It is a very tricky argument I must admit - because, correct me if I wrong, Vorbis triggers to short block if the amplitude level change between consecutive frequency bands in time (meeting claim #8)  - this is ... well... at least looks like "changing of the signal amplitude"
Title: Vorbis development, status & patent issues
Post by: rsilva on 2003-10-07 19:17:34
Let me try to "preach to the deaf" once again...

Before trying to decide "scientifically" if a codec infringes on a patent, one has to know "scientifically"
what the patent claim means. Unfortunately patent claims are not written by scientists, but they
are written by lawyers with intentional vagueness. The objective is to make it as broad as possible and, eventually, denfend it in court. Hence, any tentative to seriously analyze a patent situation should involve a lawyer to "extract" the precise meaning of the patent claim. Worse, a definitive answer needs a judge.

Otherwise, all of our arguments will have to start with a "According to my analysis of claims patent", as Ivan's post above. The same aspect of possible different interpretations was raised by sthayashi in another post.

Is it clear now why Xiph should avoid to answer this thread without consulting a lawyer?

Considering these arguments, is it technically sound to "ask scientifically if a patent is being infringed"? Hey, I just stated a meta-question  !  I have the opinion that the answer of this question is no. However most people here seems to ignore this aspect and insist on having a pseudo-scientific discussion on a matter that is not solely in the science domain.
Title: Vorbis development, status & patent issues
Post by: sthayashi on 2003-10-07 20:41:48
Quote
Well, defending Xiph position can be done on two basis:

#1 Attacking claim 1 with argument that vorbis do not code spectrum, but residual

#2 Attacking claim 1 with argument that switching criterion is different from "signal amplitude change"

Personally, I think argument #1 can't be very helpful, because the final result before IMDCT in decoder is actual MDCT signal - which is overlapped and added, so the signal is "coded" no matter how the coding representation is done in the encoder/bitstream (LPC+VQ or direct scalar quantization of the coefficients, like in MP3/AAC) - and the patent does not go into the coding implementation at all.

Argument #2 is more serious - and the validity of it is only subject to determining if Parseval's theorem applies - i.e., is checking envelope level change in threshold bands equal to "signal amplitude change"... but we have another problem - patent does not specify whether "signal amplitude change" is in time or frequency domain, or how should checking/triggering be done at all!

It is a very tricky argument I must admit - because, correct me if I wrong, Vorbis triggers to short block if the amplitude level change between consecutive frequency bands in time (meeting claim #8)  - this is ... well... at least looks like "changing of the signal amplitude"

I'm too uneducated to figure out your statement for #1.

As for #2, that spells a big oops for Xiph. I've got a question though. Is there any documentation on how the encoder chooses between short and long window sizes? I mean, I believe you, but I have to see it myself, because that's strong evidence of infringement, IMHO.
Title: Vorbis development, status & patent issues
Post by: ScorLibran on 2003-10-07 21:20:44
Quote
Quote
#2 Attacking claim 1 with argument that switching criterion is different from "signal amplitude change"

As for #2, that spells a big oops for Xiph. I've got a question though. Is there any documentation on how the encoder chooses between short and long window sizes? I mean, I believe you, but I have to see it myself, because that's strong evidence of infringement, IMHO.

Here's a page (http://www.xiph.org/archives/vorbis-dev/199908/0007.html) from the Xiph.org developement forum that may shed some light.

Excerpt:
"Vorbis simply normalizes the time-domain envelope before the MDCT.
Each block is scanned for a dynamic range increase over a
predetermined threshhold; the envelope of the time domain signal is
normalized from the point of the change to the end of the block
(current code normalizes to an even =/- 6dB). The envelope is cheap
to compute, easy to encode efficiently (most blocks don't need it, so
we don't encode an envelope in 98% of the blocks) and simple. My
tests with 'castanets.wav' gets better results than with LAME or
Fraunhofer (IMHO ;-) Needless to say, I was a bit surprised."


(Note:  This is from August 1999, but the core functionality of the codec has not changed, has it?)

From what I've studied about the architecture of the Vorbis codec over the past week or so, it seems to be using some variant of signal-amplitude changes to determine window size, but the use of "envelope pre-clamping" has to also be considered before determining whether this is ultimately infringing on the patent in question, if it (if I'm reading this right) normalizes the signal before the MDCT step.  (Does signal = time/domain envelope?)  Also, Monty covers some other points which he believes avoids other MPEG-related patents as well in the linked post.

Everyone's probably already seen this, but it seems relevant right about now.

Edit:  Here's a hopefully more relevant reference to the similarity between Vorbis and MPEG codecs concerning how window size determination is done...

"Vorbis is a hybrid transform domain general purpose audio encoder,
like MPEG in some respects (it is rooted in much of the same basic
theory). For the most part, the similarity comes from the fact that
(like nearly all modern audio compressions), Vorbis codes primarily in
the MDCT domain, using nominal 50% overlap with a y=sin(2PI*sin^2(x))
window (the window is a bit unique). The current Vorbis code and
working spec support switching between two block sizes which must
result in power-of-two sized windowed blocks. From here, the details
diverge." ...
Title: Vorbis development, status & patent issues
Post by: Ivan Dimkovic on 2003-10-07 23:00:58
Quote
"Vorbis is a hybrid transform domain general purpose audio encoder,
like MPEG in some respects (it is rooted in much of the same basic
theory). For the most part, the similarity comes from the fact that
(like nearly all modern audio compressions), Vorbis codes primarily in
the MDCT domain, using nominal 50% overlap with a y=sin(2PI*sin^2(x))
window (the window is a bit unique). The current Vorbis code and
working spec support switching between two block sizes which must
result in power-of-two sized windowed blocks. From here, the details
diverge." ...


Which is exactly what patent is covering: window-switched MDCT filterbank with variable sized windows depending on a signal statistics - the thing on which Vorbis, MP3, AAC and some other codecs rely - OTOH, how Vorbis codes MDCT coefficients is not relevant for the mentioned patent - it does not have any claim related to coding method of the MDCT spectrum.

Quote
From what I've studied about the architecture of the Vorbis codec over the past week or so, it seems to be using some variant of signal-amplitude changes to determine window size, but the use of "envelope pre-clamping" has to also be considered before determining whether this is ultimately infringing on the patent in question, if it (if I'm reading this right) normalizes the signal before the MDCT step. (Does signal = time/domain envelope?) Also, Monty covers some other points which he believes avoids other MPEG-related patents as well in the linked post.


In my opinion - if it norlalizes it by a constant function over time, it does not release it from the claim - since it is still decision based on amplitude change, but just protected with some kind of pre-echo control mechanism.

But that is just my opinion.
Title: Vorbis development, status & patent issues
Post by: Ivan Dimkovic on 2003-10-07 23:04:54
Quote

Quote
I'm too uneducated to figure out your statement for #1.


To put it in a simple way - one of the ways to expose Vorbis' "patent-freeness" was the statement that Vorbis does not code MDCT spectrum like MP3 / AAC do. Which is true - the method used in Vorbis is quite different from MP3/AAC.

However, the relevant patent in question does not deal with the MDCT coding at all - what is important is that analysis is done on MDCT windows, and after decoding of the coefficients the result is again - MDCT spectrum which is then passed through IMDCT filterbank to get PCM signal.  And the patent is directed towards filterbank  only - not the coding method.

Quote
As for #2, that spells a big oops for Xiph. I've got a question though. Is there any documentation on how the encoder chooses between short and long window sizes? I mean, I believe you, but I have to see it myself, because that's strong evidence of infringement, IMHO.


Some of the people revealed some ideas how vorbis switches to short blocks  in previous posts, and you can look at envelope.c  in /lib directory of libvorbis package to see how the idea is implemented in the code.
Title: Vorbis development, status & patent issues
Post by: PatchWorKs on 2003-10-08 09:39:09
From XviD.org website:

Quote
European parliament votes _against_ software patents

This is big news for all users and programmers of XviD in the EU: The european parliament has decided that "inventions" which consist purely of software cannot be protected by patents. This is of course just the way it has always been in europe, but lately there had been much lobby work by "important companies" to have that changed. Until a few weeks ago, it looked like software patents would be introduced in europe within a few month.

The plans would most likely have allowed so-called trivial patents like the famous "one-click-patent" by amazon.com to be possible in europe also. This would have been a serious threat to almost all Open Source development in europe, because there isn't the simplest idea in software development -and in particular in video compression- that isn't under US patent by somebody.
For the experts of you: storing motion vectors relative to a predictor is "protected", MPEG-4's 3dimensional VLCs (run,level,last) aren't free, there even is (or used to be) a patent on YUV as a color space for image compression...

After today's decision, it seems that europe will stay free of such
outgrowth, at least for while...

In you are interested, do have a look at the lots of material at http://www.ffii.org/ (http://www.ffii.org/) or simply search google for "trivial patents".


So video coding differs from audio coding in patent issues ?

Sorry to be so boring... 
Title: Vorbis development, status & patent issues
Post by: Ivan Dimkovic on 2003-10-08 10:07:20
I don't know what XVid claims (and for what particular technology/algorithm they think software patent might apply), but I have a strong feeling that video coding patents for MPEG-2 and MPEG-4 are also internationally recognized PCT patents registered years ago, and have nothing to do with US pure-software patents (like that amazon crap).

Edit - ok here is the part of the list of "Non-US" patents in MPEG-4 visual :

http://www.mpegla.com/mpeg4v/m4v_patentlist.html (http://www.mpegla.com/mpeg4v/m4v_patentlist.html)

FR 2,599,577
DE 3767919
GB 248,711
IT 248,711
SE 248,711
FR 395,709
GB 395,709
JP 2,790,509
DE 3855203
JP 2,998,741
JP 3,092,610
JP 3,092,613
JP 3,191,935
JP 3,303,869
JP 1,835,550
DE 69031107
FR 424,026
GB 424,026
JP 2,712,645
AT 185663
BE 638,218
CH/LI 638,218
DE 69421135
DK 638,218
ES 2,137,358
FR 638,218
GB 638,218
GR 3,032,133
IE 638,218
IT 638,218
LU 638,218
MC 638,218
NL 638,218
PT 638,218
SE 638,218
DE 69031045
FR 584,840
GB 584,840
JP 2,137,325
NL 584,840
DE 69024235
DE 69030819
FR 379,217
FR 572,046
GB 379,217
GB 572,046
JP 2,072,546
Title: Vorbis development, status & patent issues
Post by: Ivan Dimkovic on 2003-10-08 11:27:09
Quote
Sorry to be so boring... 


Sorry if I sounded too harsh regarding the issue (and you started with "maybe I am too boring) - consider this as a joke, and nothing else.

You are not boring, but your resoning actually describes the false information from some sources regarding patents - I dont' think it is intentional in most cases,  it just proves that somebody is not informed about patent system.

Most MPEG related patents are not "software patents" in strict term, and they are registered throughout all the world (Sheesh - some SBR patents are now registered even in Yugoslavia - country where I was born,  and I was quite surprised when I saw that in the country list)

So, the typical "we are against software patents" rant (including "It might be illegal in U.S. but it is not in Europe" (which is IMO quite reasonable - and has some logical and phylosophical points) simply does not apply to audio/visual coding algorithms,  and pushing it into the technical discussion like this is simly just adding unwanted noise.

And, even if some patent is idea used in a product without paying a "fee" this does not render product "illegal" or anything like that - some patents are registered with some other ideas in mind, and not all patent holders chase people who use their ideas.
Title: Vorbis development, status & patent issues
Post by: Garf on 2003-10-08 17:07:42
Quote
(Note:  This is from August 1999, but the core functionality of the codec has not changed, has it?)

It has. They switched to window-switching. Some things have been massively changed since that time, and the quoted mail is also wrong about how AAC works.

(As far as I understand)
Title: Vorbis development, status & patent issues
Post by: Diocletian on 2003-10-09 18:27:32
Quote
Quote

e.g. if the complete technological details were publicly available more than 20 years ago, then this technology is patent free. If there was a patent before, it has now expired. If there was a (same, similar or encompassing) patent filed more recently, then it doesn't cover this technology.


The thing is,  which is core of this discussion - is that adaptive window switched MDCT filterbanks didn't exist 20 years ago - they were result of work of H.Malvar, J. Princen, A. Bradley and, finally, B. Edler (dynamic switching)  in late 80's.

Do you have the exact text of this patent? What is the property of the MDCT
filter which is patented?


      ................... = const


What is the text for .................. in the patent paper?
Title: Vorbis development, status & patent issues
Post by: ScorLibran on 2003-10-09 19:09:38
Quote
Do you have the exact text of this patent?

US 5,214,742: "Method for transmitting a signal" (http://patft.uspto.gov/netacgi/nph-Parser?Sect1=PTO1&Sect2=HITOFF&d=PALL&p=1&u=/netahtml/srchnum.htm&r=1&f=G&l=50&s1=5,214,742.WKU.&OS=PN/5,214,742&RS=PN/5,214,742)
Inventors: Edler; Bernd (Hanover, DE)
Filed: October 1, 1990
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