Opened 22 months ago

Closed 21 months ago

Last modified 19 months 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@…> 22 months 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@…> 22 months 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@…> 22 months 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@…> 22 months 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@…> 22 months 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@…> 22 months 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@…> 22 months 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 22 months ago by Bjoern Voigt <bjoernv@…>

Sample video with 5.1 audio download link and mediainfo output

Changed 22 months ago by Bjoern Voigt <bjoernv@…>

Playback log without options for the unpatched MythTV 0.29 frontend

Changed 22 months ago by Bjoern Voigt <bjoernv@…>

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

Changed 22 months ago by Bjoern Voigt <bjoernv@…>

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

Changed 22 months ago by Bjoern Voigt <bjoernv@…>

Playback log without options for the patched MythTV 0.29 frontend

Changed 22 months ago by Bjoern Voigt <bjoernv@…>

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

Changed 22 months ago by Bjoern Voigt <bjoernv@…>

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

comment:1 Changed 22 months 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 22 months ago by Stuart Auchterlonie

Milestone: 29.10.28.2

Moving remaining open tickets to 0.28.2 milestone

comment:3 Changed 22 months ago by Stuart Auchterlonie

Milestone: 0.28.229.2

Moving remaining open tickets to 29.2 milestone

comment:6 Changed 21 months 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 21 months ago by Peter Bennett (previous) (diff)

comment:7 Changed 21 months ago by Peter Bennett

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

comment:8 Changed 19 months ago by Peter Bennett

Owner: changed from Peter Bennett to Peter Bennett
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