Opened 7 years ago
Closed 7 years ago
Last modified 7 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: | 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)
Change History (13)
Changed 7 years ago by
| Attachment: | mythtv-dvb-t2-6-audio-channels-sample.txt added |
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Changed 7 years ago by
| Attachment: | dvb-t2-6-audio-channels-sample-playback-unpatched-mythtv.log added |
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Playback log without options for the unpatched MythTV 0.29 frontend
Changed 7 years ago by
| Attachment: | dvb-t2-6-audio-channels-sample-playback-unpatched-mythtv-v-decode-audio-playback.log added |
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Playback log with the options "-v decode,audio,playback" for the unpatched MythTV 0.29 frontend
Changed 7 years ago by
| Attachment: | mythtv-29-aac-6-channel-audio-backport.patch added |
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Patch for MythTV 0.29 for 6 channel AAC playback (backport from FFmpeg 3.3)
Changed 7 years ago by
| Attachment: | dvb-t2-6-audio-channels-sample-playback-patched-mythtv.log added |
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Playback log without options for the patched MythTV 0.29 frontend
Changed 7 years ago by
| Attachment: | dvb-t2-6-audio-channels-sample-playback-patched-mythtv-v-decode-audio-playback.log added |
|---|
Playback log with the options "-v decode,audio,playback" for the patched MythTV 0.29 frontend
Changed 7 years ago by
| Attachment: | mythtv-dvb-t2-2-audio-channels-sample.txt added |
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Sample video with stereo audio download link and mediainfo output (works for patched and unpatched MythTV))
comment:1 Changed 7 years ago by
| Owner: | changed from JYA to Peter Bennett |
|---|---|
| Status: | new → accepted |
I will resync MythTV to ffmpeg 3.4 rather than commit this patch.
comment:2 Changed 7 years ago by
| Milestone: | 29.1 → 0.28.2 |
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Moving remaining open tickets to 0.28.2 milestone
comment:3 Changed 7 years ago by
| Milestone: | 0.28.2 → 29.2 |
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Moving remaining open tickets to 29.2 milestone
comment:6 Changed 7 years ago by
The resync has been done and committed to master on Feb 13th 2018. see 24f44de
comment:7 Changed 7 years ago by
| Milestone: | 29.2 → 30.0 |
|---|---|
| Resolution: | → Fixed |
| Status: | accepted → closed |
| Type: | Patch - Bug Fix → Bug Report - General |
comment:8 Changed 7 years ago by
| Owner: | changed from Peter Bennett to Peter Bennett |
|---|
Sample video with 5.1 audio download link and mediainfo output