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.

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.

    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);

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.

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.

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.

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.

(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

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.

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.

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.

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.

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).

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.

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.

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.