Support >6 channels in E-AC-3 audio encoder

[11rcombs]

E-AC-3 supports up to 15 full-bandwidth channels, but libavcodec's encoder currently doesn't support 6.1 and 7.1 channel layouts. Do these layouts just need to be added to ff_ac3_channel_layouts, or would this require additional work on the encoder?

[LigH]

This does not only belong to the E-AC-3 encoder, but also to the decoder or the format recognition in general. There is a report in the German doom9/Gleitz video forum that ffmpeg does not even recognize a 7.1 channel Blu-ray audio stream correctly, which consists of a 5.1 AC-3 core and additional E-AC-3 channels. It may have been related to a slightly older version; a rather current ffmpeg version (N-81308-g369ed11, 2016-08-09) prints a warning that it will handle only the 5.1 core:

[eac3 @ 0000000002a8f900] Dependent substream decoding is not implemented. Update your FFmpeg version to the newest one from Git. If the problem still occurs, it means that your file has a feature which has not been implemented.
[eac3 @ 0000000002a8f900] If you want to help, upload a sample of this file to ftp://upload.ffmpeg.org/incoming/ and contact the ffmpeg-devel mailing list. (ffmpeg-devel@ffmpeg.org)

Possibly relevant: MediaInfo? does not recognize it correctly either (e.g. reports an obviously improbable bitrate of 500 bytes per second).

[LigH]

7.1 channel Blu-ray E-AC-3 with 5.1 AC-3 core and 2 dependent substreams

[cehoyos]

Is this the one sample we know about (from a demo disk) or a new file?

[LigH]

AFAIK it's a new file, extracted from a Blu-ray by a Gleitz forum member.

​http://forum.gleitz.info/showthread.php?47670-e-ac3-richtig-convertieren

[cehoyos]

Then please ask for a longer sample that provides actual audible sound (at least 2,5M) and ask which Bluray this is.

[cehoyos]

Two minute eac3 7.1 sample (that does not come from the demo disk) uploaded to ​http://samples.ffmpeg.org/ffmpeg-bugs/trac/ticket3595/

[dcxero]

Replying to LigH:

Possibly relevant: MediaInfo? does not recognize it correctly either (e.g. reports an obviously improbable bitrate of 500 bytes per second).

MediaInfo? only seems to have a bug reading 7.1 Dolby Digital Plus tracks authored using the Blu-ray Disc profile (which is what the other samples use). It can read 7.1 Dolby Digital Plus tracks authored using the standard profile (which is used more for software and file/streaming distribution)

Here is a Standard profile 7.1 sample: ​https://www.datafilehost.com/d/ae18d85c