Welcome to Doom9's Forum, THE in-place to be for everyone interested in DVD conversion. Before you start posting please read the forum rules. By posting to this forum you agree to abide by the rules. |
|
17th January 2019, 13:47 | #1 | Link |
Registered User
Join Date: Mar 2004
Posts: 1,125
|
Dolby AC-4 decoding support?
It seems as though vlc player and mpc-be do not support Dolby AC-4. From reading Dolby's own website (https://dolbyac4.com/uk/) it appears that U.K free-to-air satellite platform 'Freesat' has picked AC-4 as the exclusive next gen audio format for their 3rd generation satellite boxes that will be released this year. Therefore AC-4 broadcasts will likely happen this year not just a trial. It would be nice if FFmpeg/vlc/mpc-be added support to decode this audio codec. Does anyone know if work is being done in any of these to add support?
|
27th January 2019, 22:23 | #2 | Link |
Registered User
Join Date: Mar 2004
Posts: 1,125
|
I found this, not sure if it will be helpful for us: https://github.com/DolbyLaboratories/dlb_mp4base
|
28th January 2019, 08:55 | #3 | Link | |
SuperVirus
Join Date: Jun 2012
Location: Antarctic Japan
Posts: 1,351
|
Quote:
|
|
20th February 2019, 22:37 | #4 | Link |
Registered Developer
Join Date: Mar 2010
Location: Hamburg/Germany
Posts: 10,346
|
Some work for FFmpeg to support AC-4 decoding has begun. When it'll be complete and/or usable .. we'll see.
__________________
LAV Filters - open source ffmpeg based media splitter and decoders |
28th February 2019, 18:53 | #7 | Link |
Registered Developer
Join Date: Mar 2010
Location: Hamburg/Germany
Posts: 10,346
|
If anyone has any AC-4 samples, that would be helpful for development. Preferably real-world samples, the commonly found ones in the DASH test suite etc, we already got.
__________________
LAV Filters - open source ffmpeg based media splitter and decoders |
2nd March 2019, 02:19 | #8 | Link |
Registered User
Join Date: Nov 2010
Posts: 238
|
Some dvb broadcaster are sending ac4:
https://www.dvbviewer.tv/forum/topic...4-sound-track/ I can ask for a sample if it helps. |
2nd March 2019, 09:23 | #9 | Link |
Registered Developer
Join Date: Mar 2010
Location: Hamburg/Germany
Posts: 10,346
|
Already got some from the DVBViewer people, was hoping for more alternative samples to cover as much as possible, but thanks!
__________________
LAV Filters - open source ffmpeg based media splitter and decoders |
4th March 2019, 12:27 | #10 | Link | |
Registered User
Join Date: Mar 2004
Posts: 1,125
|
Quote:
|
|
13th September 2019, 17:40 | #12 | Link |
Broadcast Encoder
Join Date: Nov 2013
Location: Royal Borough of Kensington & Chelsea, UK
Posts: 2,904
|
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...
Well, I think we're about to find out in the near future. Unfortunately, I do not have a sample since nobody ever sent us an AC4 audio file, otherwise I would have shared it... |
14th September 2019, 23:00 | #13 | Link | |
RipBot264 author
Join Date: May 2006
Location: Poland
Posts: 7,815
|
Quote:
__________________
Windows 7 Image Updater - SkyLake\KabyLake\CoffeLake\Ryzen Threadripper |
|
15th September 2019, 14:09 | #14 | Link | |
Broadcast Encoder
Join Date: Nov 2013
Location: Royal Borough of Kensington & Chelsea, UK
Posts: 2,904
|
Quote:
I never really bothered to monkey around with opus to be fair, but that's only 'cause opus was born as a low-bitrate speech-optimized codec which has been extended to support other profiles for general contents encoding and because of that, its adoption has never been very widespread for general purpose contents and therefore many devices don't officially support it. For this very reason, I've been using AAC to encode audio files in lossy. It's pretty much the same reason why, whenever I gotta keep an audio file lossless, I still keep the original PCM in .wav instead of re-encoding it to FLAC: the megabytes it saves are negligible compared to the fact that almost nothing will play it. |
|
15th September 2019, 23:09 | #15 | Link | |
RipBot264 author
Join Date: May 2006
Location: Poland
Posts: 7,815
|
Quote:
__________________
Windows 7 Image Updater - SkyLake\KabyLake\CoffeLake\Ryzen Threadripper |
|
16th September 2019, 17:29 | #16 | Link | |
Life's clearer in 4K UHD
Join Date: Jun 2003
Location: Notts, UK
Posts: 12,227
|
Quote:
I would hardly call an average 50% reduction in a Flac file size over PCM file size "negligible"... Also in my case... my OPPO's, my Onkyo AVR, my Android mobile phone, my Android tablet and my LG televisions (via HDD) can play Flac files.
__________________
| I've been testing hardware media playback devices and software A/V encoders and decoders since 2001 | My Network Layout & A/V Gear |
Last edited by SeeMoreDigital; 16th September 2019 at 22:08. |
|
15th September 2019, 14:57 | #17 | Link | |
Life's clearer in 4K UHD
Join Date: Jun 2003
Location: Notts, UK
Posts: 12,227
|
Quote:
From Dolby's blog [2017]: Hearing Is Believing: Comparing Dolby AC-4 to Dolby AC-3
__________________
| I've been testing hardware media playback devices and software A/V encoders and decoders since 2001 | My Network Layout & A/V Gear |
Last edited by SeeMoreDigital; 15th September 2019 at 15:07. |
|
17th July 2023, 21:58 | #18 | Link | |
Registered User
Join Date: Aug 2009
Posts: 313
|
Quote:
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. |
|
25th January 2020, 20:38 | #20 | Link | ||
Broadcast Encoder
Join Date: Nov 2013
Location: Royal Borough of Kensington & Chelsea, UK
Posts: 2,904
|
Quote:
Quote:
add AC-4 codec id and description: http://ffmpeg.org/pipermail/ffmpeg-d...ry/240221.html add mapping for AC-4 in MP4: http://ffmpeg.org/pipermail/ffmpeg-d...ry/240222.html Both from Paul B Mahol. I also found a ticket, namely #8349 where Nomis101 asked about Decoding Support of AC4 in ffmpeg. At the very beginning they marked it as closed three months ago, but then richardpl re-opened it and it's currently opened and set to "wish". @richardpl are you one of the developers behind ffmpeg? Last edited by FranceBB; 25th January 2020 at 20:40. |
||
Thread Tools | Search this Thread |
Display Modes | |
|
|