Opened 3 years ago

Closed 2 years ago

Last modified 2 years ago

#13211 closed Bug Report - General (Fixed)

MythTV needs a backport from FFmpeg 3.3/3.4 to make German DVB-T2 HD with 5.1 audio work

Reported by: Bjoern Voigt <bjoernv@…> Owned by: Peter Bennett
Priority: major Milestone: 30.0
Component: 3rd Party - FFMPEG Version: v29-fixes
Severity: medium Keywords: dvb, t2, hevc, latm, aac, ffmpeg
Cc: Ticket locked: no

Description

Broadcasts in German DVB T2 contain 2 channels (Stereo) or 6 channels (5.1 surround) audio. Especially cinema movies and shows often use 6 channels. Broadcasts with 2 channels work without problems in MythTV.

But broadcasts with 6 audio channels cause sloppy sound, error messages and as a result also sloppy video playback. There are two log files with the error message for a sample video recording attached using the original MythTV version (fixes/29 branch).

The root cause for this issue is, that MythTV uses FFmpeg 3.2, but the relevant bug was only fixed for FFmpeg 3.3, 3.4 or higher:

Problem transcoding 5.1 AAC LATM audio streams https://trac.ffmpeg.org/ticket/4544

Unfortunately the patch in FFmpeg bug report 4544 itself is not sufficient.

I had to backport some more changes from FFmpeg 3.3 to fix the problem. Since I am no FFmpeg developer and no export for AAC decoding I do not know, if the patch is minimal.

My current version of the patch contains 499 lines for two FFmpeg files.

I have tested the patched MythTV version on daily use. I have not found any issues.

Some more attachments show playback logs for the patched version.

Attachments (7)

mythtv-dvb-t2-6-audio-channels-sample.txt (4.2 KB) - added by Bjoern Voigt <bjoernv@…> 3 years ago.
Sample video with 5.1 audio download link and mediainfo output
dvb-t2-6-audio-channels-sample-playback-unpatched-mythtv.log (23.3 KB) - added by Bjoern Voigt <bjoernv@…> 3 years ago.
Playback log without options for the unpatched MythTV 0.29 frontend
dvb-t2-6-audio-channels-sample-playback-unpatched-mythtv-v-decode-audio-playback.log (67.6 KB) - added by Bjoern Voigt <bjoernv@…> 3 years ago.
Playback log with the options "-v decode,audio,playback" for the unpatched MythTV 0.29 frontend
mythtv-29-aac-6-channel-audio-backport.patch (19.8 KB) - added by Bjoern Voigt <bjoernv@…> 3 years ago.
Patch for MythTV 0.29 for 6 channel AAC playback (backport from FFmpeg 3.3)
dvb-t2-6-audio-channels-sample-playback-patched-mythtv.log (9.3 KB) - added by Bjoern Voigt <bjoernv@…> 3 years ago.
Playback log without options for the patched MythTV 0.29 frontend
dvb-t2-6-audio-channels-sample-playback-patched-mythtv-v-decode-audio-playback.log (25.6 KB) - added by Bjoern Voigt <bjoernv@…> 3 years ago.
Playback log with the options "-v decode,audio,playback" for the patched MythTV 0.29 frontend
mythtv-dvb-t2-2-audio-channels-sample.txt (4.2 KB) - added by Bjoern Voigt <bjoernv@…> 3 years ago.
Sample video with stereo audio download link and mediainfo output (works for patched and unpatched MythTV))

Download all attachments as: .zip

Change History (13)

Changed 3 years ago by Bjoern Voigt <bjoernv@…>

Sample video with 5.1 audio download link and mediainfo output

Changed 3 years ago by Bjoern Voigt <bjoernv@…>

Playback log without options for the unpatched MythTV 0.29 frontend

Changed 3 years ago by Bjoern Voigt <bjoernv@…>

Playback log with the options "-v decode,audio,playback" for the unpatched MythTV 0.29 frontend

Changed 3 years ago by Bjoern Voigt <bjoernv@…>

Patch for MythTV 0.29 for 6 channel AAC playback (backport from FFmpeg 3.3)

Changed 3 years ago by Bjoern Voigt <bjoernv@…>

Playback log without options for the patched MythTV 0.29 frontend

Changed 3 years ago by Bjoern Voigt <bjoernv@…>

Playback log with the options "-v decode,audio,playback" for the patched MythTV 0.29 frontend

Changed 3 years ago by Bjoern Voigt <bjoernv@…>

Sample video with stereo audio download link and mediainfo output (works for patched and unpatched MythTV))

comment:1 Changed 3 years ago by Peter Bennett

Owner: changed from JYA to Peter Bennett
Status: newaccepted

I will resync MythTV to ffmpeg 3.4 rather than commit this patch.

comment:2 Changed 3 years ago by Stuart Auchterlonie

Milestone: 29.10.28.2

Moving remaining open tickets to 0.28.2 milestone

comment:3 Changed 3 years ago by Stuart Auchterlonie

Milestone: 0.28.229.2

Moving remaining open tickets to 29.2 milestone

comment:6 Changed 2 years ago by Peter Bennett

The resync to ffmpeg 3.4.1 has been done and committed to master on Feb 13th 2018. see 24f44de

Last edited 2 years ago by Peter Bennett (previous) (diff)

comment:7 Changed 2 years ago by Peter Bennett

Milestone: 29.230.0
Resolution: Fixed
Status: acceptedclosed
Type: Patch - Bug FixBug Report - General

comment:8 Changed 2 years ago by Peter Bennett

Owner: changed from Peter Bennett to Peter Bennett
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