Opened 7 months ago

Closed 7 months ago

Last modified 7 months ago

#6983 closed defect (duplicate)

AAC encoder breaking 5.1 LFE channel

Reported by: elsiko Owned by:
Priority: normal Component: avcodec
Version: git-master Keywords:
Cc: Blocked By:
Blocking: Reproduced by developer: no
Analyzed by developer: no

Description

Summary of the bug:
For a long time now, I've been doing some encodings into x265/aac using ffmpeg.
Recently I started noticing a problem with the audio channels that get - I think - mixed up.

The original file media info would show:
Front: L C R, Side: L R, LFE

But the encoded file will show:
Front: L C R, Side: C, Back: L R

I'm no expert, but I think the LFE channel is either dropped or converted.
I think this behaviour started around December 2017.

To be certain that something indeed changed, I encoded a file twice, used two static builds (from here: https://johnvansickle.com/ffmpeg/), once using a build from 2017-09-02, and one from 2018-01-24.

I attached to the tickets the logs of both encodings, the media info (+ the original).
You can download the original mkv file, as well as encoded files from there: http://176.9.126.245/encoding-results/

You can clearly see in the mediainfo of 2017 that the channels were correct (with LFE), but that's not the case in the 2018 encoding.

One last thing, I think this problem might be related to this ticket: https://trac.ffmpeg.org/ticket/6965

Attachments (5)

mediainfo_originalfile.txt (5.4 KB) - added by elsiko 7 months ago.
Original Mkv - Mediainfo
mediainfo_build2017.txt (7.4 KB) - added by elsiko 7 months ago.
Re-encoded mkv (2017 build) - Mediainfo
mediainfo_build2018.txt (7.5 KB) - added by elsiko 7 months ago.
Re-encoded mkv (2018 build) - Mediainfo
encoding_build2017.txt (10.5 KB) - added by elsiko 7 months ago.
Encoding logs - 2017 build
encoding_build2018.txt (10.6 KB) - added by elsiko 7 months ago.
Encoding logs - 2018 build

Download all attachments as: .zip

Change History (9)

Changed 7 months ago by elsiko

Original Mkv - Mediainfo

Changed 7 months ago by elsiko

Re-encoded mkv (2017 build) - Mediainfo

Changed 7 months ago by elsiko

Re-encoded mkv (2018 build) - Mediainfo

Changed 7 months ago by elsiko

Encoding logs - 2017 build

Changed 7 months ago by elsiko

Encoding logs - 2018 build

comment:1 Changed 7 months ago by elsiko

  • Summary changed from AAC encoder breaking 5.1 channels to AAC encoder breaking 5.1 LFE channel

comment:2 Changed 7 months ago by cehoyos

  • Resolution set to duplicate
  • Status changed from new to closed

See #6965, consider telling us there which decoders fail.

comment:3 Changed 7 months ago by elsiko

Media info is giving this info, does it mean it is not reliable?

comment:4 Changed 7 months ago by cehoyos

It means if all decoders you tested work as expected, FFmpeg’s behaviour will not change.

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