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Recent Posts
21
Other Lossy Codecs / Re: Patent expiration for E-AC3 (Dolby Digital Plus)?
Last post by kurkosdr -
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.
22
Other Lossy Codecs / Re: Patent expiration for E-AC3 (Dolby Digital Plus)?
Last post by kurkosdr -
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.
23
Other Lossy Codecs / Re: Patent expiration for E-AC3 (Dolby Digital Plus)?
Last post by saratoga -
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). 
25
3rd Party Plugins - (fb2k) / Re: Linear Phase Subwoofer
Last post by CitizenInsomniac -
Some questions about this component:
1. Is there any documentation which describes the various filters available?
2. Are any of the filters considered better than others? Any reason to use anything other than the default filter?
3. When given a multi-channel audio signal as input does the DSP use only FL+FR or does it use all channels to derive the bass frequencies?
4. Are the bass frequencies removed from the input channels or are input channels left untouched?
5. What does L/R sync do?
6. What is the expected LFE channel output volume level relative to the other channels? Are additional volume adjustments typically necessary?

Any or all responses much appreciated. :)
27
Lossless / Other Codecs / Re: Monkey's Audio - Observations and the need to update some statements on the net?
Last post by kode54 -
Off-topic, page description for Cog updated to include the two extra codecs that were long supported, but not actually listed in the features page. Namely, Monkey's Audio and TAK. I don't support either one via their official libraries, but by FFmpeg, so features may be missing. I did test general support, though. Wavpack is also supported, including floating point and DSD. I do the DSD decimation and downsampling myself, though.
30
Other Lossy Codecs / Re: Patent expiration for E-AC3 (Dolby Digital Plus)?
Last post by IgorC -
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