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Old 19th December 2020, 20:04   #41  |  Link
Reino
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@richardpl are you one of the developers behind ffmpeg?
richardpl = Paul B Mahol.
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Old 18th January 2021, 14:43   #42  |  Link
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It looks as though AC-4 decoding is working now in ffmpeg builds: https://trac.ffmpeg.org/ticket/8349

Very cool, can't wait for a stable version of FFmpeg to be released supporting it.
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Old 19th March 2021, 17:02   #43  |  Link
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It looks as though AC-4 decoding is working now in ffmpeg builds: https://trac.ffmpeg.org/ticket/8349

Very cool
That's so cool, considering that the alternative would be buying a super expensive Dolby DP580!!
Well done, everybody!
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Old 27th November 2022, 05:08   #44  |  Link
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Does anyone know of a static build that can be downloaded with AC-4 support?
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Old 13th July 2023, 19:45   #45  |  Link
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Sharing such binary would break Dolby IP rules and is big legal offence.
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Old 17th July 2023, 21:58   #46  |  Link
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AC3 has been a good and reliable codec for ages but it needed an high enough bitrate, something like 320-384 kbit/s to sound really good and now there's AC4... How is it gonna be compared to AAC at no so high bitrates like 128-192 kbit/s, I wonder...
The big sell of AC4 is that it can separate dialogue from music and effects, so you can have multiple "dialogue" groups for the different languages sharing one "music and effects" group (and the AC4 decoder can mix the chosen "dialogue" group with the "music and effects" group to give the final output), which is where the big bitrate savings come from. There are countries in the EU which are bilingual or even trilingual, so even when using efficient audio formats giving 96Kbps per stream, you are still looking at ~0.3Mbps just for audio.

One remaining question is if AC4 supports full (albeit lossy) Atmos (aka how many ceiling channels it supports). Haven't found a clear answer to that so far.

Last edited by kurkosdr; 18th July 2023 at 13:49.
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Old 17th July 2023, 22:03   #47  |  Link
kurkosdr
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Sharing such binary would break Dolby IP rules and is big legal offence.
Which brings up that other important question: Since AC4 is an essential format for watching HEVC free-to-air terrestrial broadcasts in some countries, do we have a patent list?

Last edited by kurkosdr; 17th July 2023 at 22:30.
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Old 17th July 2023, 22:12   #48  |  Link
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What different compared to other patented codecs?
Software patents are meaningless in for example France, so why could VLC not use it in a binary?
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Old 17th July 2023, 22:35   #49  |  Link
kurkosdr
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What different compared to other patented codecs?
Software patents are meaningless in for example France, so why could VLC not use it in a binary?
VideoLAN (VLC), which is based in France, can do that, websites based in the US (or other countries enforcing software patents) can't.

Last edited by kurkosdr; 18th July 2023 at 04:31.
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