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Topic: Patent expiration for E-AC3 (Dolby Digital Plus)? (Read 1879 times) previous topic - next topic
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Patent expiration for E-AC3 (Dolby Digital Plus)?

E-AC3 (aka Dolby Digital Plus) is used exclusively for some terrestrial television broadcasts in Europe. For example:
https://www.digitalbitrate.com/dtv.php?mux=MUXA&liste=1&live=3&lang=en
https://www.digitalbitrate.com/dtv.php?mux=R1,IDF&liste=1&live=1&lang=en

This got me thinking:

- Is there a patent list (and anticipated expiration date) for "demuxing" the legacy stream inside the E-AC3 stream to AC3?
 
- Is there a patent list (and anticipated expiration date) for decoding E-AC3 (with the extra channels etc)?

I've tried Googling around and there is no information on the subject. All I can find is people talking about the expiration of AC3 patents and a ETSI patent declaration from 2004 (which, considering how old it is, I am not sure it covers E-AC3).

In fact, even pinpointing a "release date" for E-AC3 has also been impossible for me. Even Wikipedia doesn't have that information. Best I can find is that E-AC3 was a mandatory format for HD-DVD, and since the first HD-DVD player was released on 31st March 2006 (and has a "Dolby Digital Plus" badge), this gives us a "worst case" date of 31st March 2006 when it comes to prior art.

Anyone has any information on the topic?

PS: The DigitalBitrate website can tell the difference between AC3 and E-AC3 (example of AC3 identified here), so the examples above are not a case of a misidentified stream. You really need an E-AC3 decoder (or at the very least, "demuxer") to watch terrestrial TV in some EU countries...

Re: Patent expiration for E-AC3 (Dolby Digital Plus)?

Reply #1
Here are some mentions about E-AC3 back in 2004.

https://professional.dolby.com/globalassets/dolby-digital-plus/aes-convention-paper-intro-to-dolby-digital-plus.pdf
https://tech.ebu.ch/docs/techreview/trev_301-dolby.pdf

It doesn't strictly mean that all decoding/demuxing patents are from 2004 or prior to that date.  Hard work with an involvment of lawyers would need.

P.S. As of AC3, it's safe to say that its decoding patents are expired. https://www.wowza.com/community/t/ac3-decoding-support-all-patents-expired/50090

Re: Patent expiration for E-AC3 (Dolby Digital Plus)?

Reply #2
Here are some mentions about E-AC3 back in 2004.

https://professional.dolby.com/globalassets/dolby-digital-plus/aes-convention-paper-intro-to-dolby-digital-plus.pdf
https://tech.ebu.ch/docs/techreview/trev_301-dolby.pdf
These are indeed mention, not proof of implementation. This could just be a "proposal" with the actual implementation coming later.

It doesn't strictly mean that all decoding/demuxing patents are from 2004 or prior to that date.  Hard work with an involvment of lawyers would need.
Still, it's useful when it comes to eliminating patents after that date, assuming a patent list is found somewhere.

P.S. As of AC3, it's safe to say that its decoding patents are expired. https://www.wowza.com/community/t/ac3-decoding-support-all-patents-expired/50090
Yes, that's a known fact.


Re: Patent expiration for E-AC3 (Dolby Digital Plus)?

Reply #4
F**k you, Dolby!

PS I maintain FOSS that decodes Dolby formats using FFmpeg.

Re: Patent expiration for E-AC3 (Dolby Digital Plus)?

Reply #5
Is there a patent list (and anticipated expiration date) for "demuxing" the legacy stream inside the E-AC3 stream to AC3?
There is no legacy AC3 stream within the E-AC3 stream. E-AC3 decoders are required to be backwards compatible with AC3 streams, but not the other way around - AC3 decoders can't decode any part of the E-AC3 bitstream, because there is no AC3 "base payload" inside them.
Perhaps you were thinking of DTS inside DTS-HD?

Re: Patent expiration for E-AC3 (Dolby Digital Plus)?

Reply #6
F**k you, Dolby!

PS I maintain FOSS that decodes Dolby formats using FFmpeg.

The sad thing is that Dolby (along with complicit broadcast regulators) are continuing the charade of making their patented formats essential to decoding public TV signals (even ones you may have already paid for via your public broadcaster levy/TV license) under the excuse of 3D audio. As if any terrestrial broadcaster will ever broadcast 3D audio when most of them aren't even broadcasting 5.1 audio. Or as if a 50Kbps saving per stereo audio stream matters, considering HEVC 4K video requires bitrates upwards of 10Mbps (so, the savings are 0.5% of the total bitstream at best for single-language content or 1.5% at best for multi-language content, hooray!). Also, for ATSC 3.0, you need both a Dolby AC4 license and a MPEG-H 3D Audio license so no patent racket feels left out of the royalty payments.

That said, I'd rather keep this thread focused on E-AC3 patent decision, not general Dolby hate.

Is there a patent list (and anticipated expiration date) for "demuxing" the legacy stream inside the E-AC3 stream to AC3?
There is no legacy AC3 stream within the E-AC3 stream. E-AC3 decoders are required to be backwards compatible with AC3 streams, but not the other way around - AC3 decoders can't decode any part of the E-AC3 bitstream, because there is no AC3 "base payload" inside them.
Perhaps you were thinking of DTS inside DTS-HD?
E-AC3 can have a legacy AC-3 bitstream embedded in it (E-AC3 audio in Blu-Rays does have it), but I admit I was confused with regards to whether its presence is mandatory. I also remember reading that HD-DVD could convert E-AC3 to AC3 with a claimed "no loss on the base 5.1 audio" (which was a selling point back in the format wars since the legacy AC-3 bitstream can be of low bitrate), so I assumed that even if a legacy AC3 bitstream isn't mandatory, there is at least a way to extract some kind of "base payload". As It turns out, no "base payload" gets extracted and the conversion is just some clever "hybrid re-compression" method (which brings the question: Is this method covered by patents? And if yes, when do they expire? Though I admit it's a very specialized question for anyone here to know).

BTW the old AC3 Freedom Day website made a reference to an E-AC3 patent, but it's based on that old ETSI patent declaration from 2004. That's all I have.

Re: Patent expiration for E-AC3 (Dolby Digital Plus)?

Reply #7
E-AC3 can have a legacy AC-3 bitstream embedded in it (E-AC3 audio in Blu-Rays does have it), but I admit I was confused with regards to whether its presence is mandatory. I also remember reading that HD-DVD could convert E-AC3 to AC3 with a claimed "no loss on the base 5.1 audio" (which was a selling point back in the format wars since the legacy AC-3 bitstream can be of low bitrate), so I assumed that even if a legacy AC3 bitstream isn't mandatory, there is at least a way to extract some kind of "base payload". As It turns out, no "base payload" gets extracted and the conversion is just some clever "hybrid re-compression" method (which brings the question: Is this method covered by patents? And if yes, when do they expire? Though I admit it's a very specialized question for anyone here to know).
You're right, I had forgotten about the ability of EAC3 to carry a legacy AC3 substream. TBH I've always been slightly puzzled by that feature, because as far as I understand it, the AC3 substream inside an EAC3 bitstream can only be detected by EAC3 decoders - which makes its value as a backwards compatible option somewhat questionable. Plus, it's a fully redundant stream, so the only advantage of it seems to be that it allows someone to package both AC3 and EAC3 in a single file instead of providing them as 2 separate files.

Re: Patent expiration for E-AC3 (Dolby Digital Plus)?

Reply #8
Looking at this list, at least with respect to the US patent family members, only 5 of the US patents are still Live and in-force at the USPTO:

  • US6774820
  • US7313519
  • US7318027
  • US7318035
  • US7516064

It looks like the last of these is set to expire at the end of January 2026.

Re: Patent expiration for E-AC3 (Dolby Digital Plus)?

Reply #9
E-AC3 can have a legacy AC-3 bitstream embedded in it (E-AC3 audio in Blu-Rays does have it), but I admit I was confused with regards to whether its presence is mandatory. I also remember reading that HD-DVD could convert E-AC3 to AC3 with a claimed "no loss on the base 5.1 audio" (which was a selling point back in the format wars since the legacy AC-3 bitstream can be of low bitrate), so I assumed that even if a legacy AC3 bitstream isn't mandatory, there is at least a way to extract some kind of "base payload". As It turns out, no "base payload" gets extracted and the conversion is just some clever "hybrid re-compression" method (which brings the question: Is this method covered by patents? And if yes, when do they expire? Though I admit it's a very specialized question for anyone here to know).
You're right, I had forgotten about the ability of EAC3 to carry a legacy AC3 substream. TBH I've always been slightly puzzled by that feature, because as far as I understand it, the AC3 substream inside an EAC3 bitstream can only be detected by EAC3 decoders - which makes its value as a backwards compatible option somewhat questionable. Plus, it's a fully redundant stream, so the only advantage of it seems to be that it allows someone to package both AC3 and EAC3 in a single file instead of providing them as 2 separate files.
I guess that a Bluray player or a STB that is capable of receiving EAC3 will be able to extract the core AC3 stream and relay that to a connected surround receiver that is capable only of AC3. Thus the physical disk need only to have one stream (EAC3) rather than two?

-k

Re: Patent expiration for E-AC3 (Dolby Digital Plus)?

Reply #10
E-AC3 can have a legacy AC-3 bitstream embedded in it (E-AC3 audio in Blu-Rays does have it), but I admit I was confused with regards to whether its presence is mandatory. I also remember reading that HD-DVD could convert E-AC3 to AC3 with a claimed "no loss on the base 5.1 audio" (which was a selling point back in the format wars since the legacy AC-3 bitstream can be of low bitrate), so I assumed that even if a legacy AC3 bitstream isn't mandatory, there is at least a way to extract some kind of "base payload". As It turns out, no "base payload" gets extracted and the conversion is just some clever "hybrid re-compression" method (which brings the question: Is this method covered by patents? And if yes, when do they expire? Though I admit it's a very specialized question for anyone here to know).
You're right, I had forgotten about the ability of EAC3 to carry a legacy AC3 substream. TBH I've always been slightly puzzled by that feature, because as far as I understand it, the AC3 substream inside an EAC3 bitstream can only be detected by EAC3 decoders - which makes its value as a backwards compatible option somewhat questionable. Plus, it's a fully redundant stream, so the only advantage of it seems to be that it allows someone to package both AC3 and EAC3 in a single file instead of providing them as 2 separate files.

As the previous commenter said, it's so that you don't have to manually choose audio streams from the menus (or by pressing the "audio" button on the remote control during playback) in order to get the higher quality track (like you had to do on DVD, where it would default to AC-3, aka the first stream, and if you wanted the DTS track you had to manually go to the menus and switch to DTS or press the "audio" button during playback to switch). Some users weren't aware they had to do this so they ended up listening AC3 on their DTS home theatres despite DTS being available. By having both AC-3 and E-AC3 on a single stream, there is only one audio stream (or at least one per language) and the E-AC3 decoder will choose whether they should export the legacy AC3 steam (if it exists), convert E-AC3 to AC3 and export (if the legacy AC3 stream doesn't exist), decode E-AC3 or export E-AC3 (the last two only if you have connected something better than plain old SPDIF).

Re: Patent expiration for E-AC3 (Dolby Digital Plus)?

Reply #11
Looking at this list, at least with respect to the US patent family members, only 5 of the US patents are still Live and in-force at the USPTO:

  • US6774820
  • US7313519
  • US7318027
  • US7318035
  • US7516064

It looks like the last of these is set to expire at the end of January 2026.

I think the patent list that is shown here:
http://blog.hobbyistsoftware.com/2014/11/dolby-codecs-software-patents-legal-threats/
also includes patents relevant to Dolby TrueHD (MLP).

Also, US6774820 has already expired according to Google Patents.

Re: Patent expiration for E-AC3 (Dolby Digital Plus)?

Reply #12
Also, US6774820 has already expired according to Google Patents.
Not a lawyer, knowing nothing about it, but ... https://hydrogenaud.io/index.php?topic=121918.msg1007144#msg1007144 . Seems like unpaid fees can make patents show up as expired - and they could be resurrected later.

(Those more familiar with the legalese, feel free to respond there as well.)
Last two months' worth of foobar2000.org ad revenue has been donated to support war refugees from Ukraine: https://www.foobar2000.org/

 

Re: Patent expiration for E-AC3 (Dolby Digital Plus)?

Reply #13
E-AC3 (aka Dolby Digital Plus) is used exclusively for some terrestrial television broadcasts in Europe. For example:
https://www.digitalbitrate.com/dtv.php?mux=MUXA&liste=1&live=3&lang=en
https://www.digitalbitrate.com/dtv.php?mux=R1,IDF&liste=1&live=1&lang=en

How about just using AC-3, MPG (Layer II), MP3 and LC-AAC?
All decoding/demuxing patents for these formats have been already expired.

That's what Italy does  :)
https://www.digitalbitrate.com/dtv.php?mux=RAI-A&liste=1&live=14&lang=en

Re: Patent expiration for E-AC3 (Dolby Digital Plus)?

Reply #14
Only useful if you know enough about the E-AC3 bitstream to strip out the compatibility layer bitstream for AC-3 decoding.

Re: Patent expiration for E-AC3 (Dolby Digital Plus)?

Reply #15
Looking at this list, at least with respect to the US patent family members, only 5 of the US patents are still Live and in-force at the USPTO:

  • US6774820
  • US7313519
  • US7318027
  • US7318035
  • US7516064

It looks like the last of these is set to expire at the end of January 2026.

Looking at the ffmpeg logs, it looks like EAC3 support was already committed before that last patent's priority date, so it is probably not essential to the decoder and only covers some additional feature or optimization. Or at least if it is essential to the decoder I don't see how you could enforce it since you could point to obvious prior art (e.g. the various decoders existing before its priority date). 

Re: Patent expiration for E-AC3 (Dolby Digital Plus)?

Reply #16
E-AC3 (aka Dolby Digital Plus) is used exclusively for some terrestrial television broadcasts in Europe. For example:
https://www.digitalbitrate.com/dtv.php?mux=MUXA&liste=1&live=3&lang=en
https://www.digitalbitrate.com/dtv.php?mux=R1,IDF&liste=1&live=1&lang=en

How about just using AC-3, MPG (Layer II), MP3 and LC-AAC?
All decoding/demuxing patents for these formats have been already expired.

That's what Italy does  :)
https://www.digitalbitrate.com/dtv.php?mux=RAI-A&liste=1&live=14&lang=en

Yes, that's the sane way to do it. If you want wide compatibility with home cinema systems (even ones that only take SPDIF), you use AC3, optimally with a secondary MPG Layer II or LC-AAC stream. I have already linked to an Italian mux in my original post btw.

In the interest of fairness, E-AC3 is useful if you want to have Atmos metadata (there is a variant of Atmos for E-AC3 known as "Dolby Digital Plus Atmos", but there is no Atmos variant for AC3 because with only 5.1 channels you aren't getting Atmos). But "Dolby Digital Plus Atmos" requires lots of channels and no broadcaster will realistically do it. Also, E-AC3 brings a negligible efficiency gain for stereo content (which is how the broadcasters that use it actually justify it).

That said, some countries do broadcast E-AC3 with no secondary stream (see my first post)., no matter what we think of that. So, at least in those countries E-AC3 is an "essential" codec for viewing public TV (aka it's not some weird codec like Dolby TrueHD that you can safely ignore for basic HD playback because even Blu-Ray has it as a non-mandatory codec).

That's why I am trying to find out the patent expiry date for E-AC3.

Re: Patent expiration for E-AC3 (Dolby Digital Plus)?

Reply #17
Looking at this list, at least with respect to the US patent family members, only 5 of the US patents are still Live and in-force at the USPTO:

  • US6774820
  • US7313519
  • US7318027
  • US7318035
  • US7516064

It looks like the last of these is set to expire at the end of January 2026.

Looking at the ffmpeg logs, it looks like EAC3 support was already committed before that last patent's priority date, so it is probably not essential to the decoder and only covers some additional feature or optimization. Or at least if it is essential to the decoder I don't see how you could enforce it since you could point to obvious prior art (e.g. the various decoders existing before its priority date). 

That patent list
http://blog.hobbyistsoftware.com/2014/11/dolby-codecs-software-patents-legal-threats/
also includes Dolby TrueHD patents.

Maybe I shouldn't have posted this list in the first place, because people are combing over the list despite the fact we don't know which of them are for Dolby TrueHD (and hence can be safely ignored). I mentioned it as a source due to how few other sources exist (only the ETSI declaration from 2004).

I find it weird that a codec that is essential for viewing TV in a country as big as France receives so little attention when it comes to its patent status.

Re: Patent expiration for E-AC3 (Dolby Digital Plus)?

Reply #18
Also, US6774820 has already expired according to Google Patents.
Not a lawyer, knowing nothing about it, but ... https://hydrogenaud.io/index.php?topic=121918.msg1007144#msg1007144 . Seems like unpaid fees can make patents show up as expired - and they could be resurrected later.

(Those more familiar with the legalese, feel free to respond there as well.)

Correct, Porcus. Looking at the USPTO's PAIR system, it appears to still be live. :)

Re: Patent expiration for E-AC3 (Dolby Digital Plus)?

Reply #19
Looking at this list, at least with respect to the US patent family members, only 5 of the US patents are still Live and in-force at the USPTO:

  • US6774820
  • US7313519
  • US7318027
  • US7318035
  • US7516064

It looks like the last of these is set to expire at the end of January 2026.

Looking at the ffmpeg logs, it looks like EAC3 support was already committed before that last patent's priority date, so it is probably not essential to the decoder and only covers some additional feature or optimization. Or at least if it is essential to the decoder I don't see how you could enforce it since you could point to obvious prior art (e.g. the various decoders existing before its priority date). 

That patent list
http://blog.hobbyistsoftware.com/2014/11/dolby-codecs-software-patents-legal-threats/
also includes Dolby TrueHD patents.

Maybe I shouldn't have posted this list in the first place, because people are combing over the list despite the fact we don't know which of them are for Dolby TrueHD (and hence can be safely ignored). I mentioned it as a source due to how few other sources exist (only the ETSI declaration from 2004).

I find it weird that a codec that is essential for viewing TV in a country as big as France receives so little attention when it comes to its patent status.

I still think the patent list is useful, as it at least defines the upper limit date after which the tech will actually be in the public domain.  It may de facto be public domain sooner, but it certainly will by within the next 4 years.