Transcoding corrupts most files

[toad@…]

The first few seconds of the file can be played normally and then the rest have no sound and half-speed video. Even with -v, mythfrontend does not report any consistent error messages when playing the corrupted files. This appears to be a video problem rather than a sound problem, as mplayer says "Too many video packets" etc (both mplayer and vlc play the video but the sound drops out). This happens for a large proportion of transcoded files. It may be related to errors in transcoding (apparently in audio), but the transcodes complete successfully, replacing the MPG with an NUV. People on IRC said that this is because MythTV uses a fork of XViD internally which is unsupported and flaky, but at least the documentation should be fixed in that case.

This is using packages built from the packaging repo and the 0.27-fixes branch. Settings include MPEG4 with high bitrates (1900kbps), 1 for audio (i.e. copy it), and high quality and 4MV.

Odd transcoding messages:

Sep 23 13:40:28 localhost mythtranscode: mythtranscode[26173]: N CoreContext? main.cpp:569 (main) Transcoding from /stuff/mp3/video/mythtv/1001_20150923123600.mpg to /stuff/mp3/video/mythtv/1001_20150923123600.mpg.tmp ... Sep 23 13:40:37 localhost mythtranscode: mythtranscode[26173]: N CoreContext? transcode.cpp:111 (GetProfile?) Transcode: Looking for autodetect profile: Autodetect from 576i Sep 23 13:40:37 localhost mythtranscode: mythtranscode[26173]: N CoreContext? transcode.cpp:136 (GetProfile?) Transcode: Using autodetect profile: Autodetect from 576i Sep 23 13:40:37 localhost mythtranscode: mythtranscode[26173]: I CoreContext? transcode.cpp:1020 (TranscodeFile?) Copying Audio while transcoding Video

Sep 23 13:42:02 localhost mythtranscode: mythtranscode[26173]: E VideoDecodeBuffer? avformatdecoder.cpp:4773 (ProcessAudioPacket?) AFD: Unknown audio decoding error Sep 23 13:42:04 localhost mythtranscode: mythtranscode[26173]: E VideoDecodeBuffer? avformatdecoder.cpp:4955 (GetFrame?) decoding error#012#011#011#011eno: Unknown error 541478725 (541478725)

Sep 23 13:42:04 localhost mythtranscode: mythtranscode[26173]: N CoreContext? main.cpp:700 (main) Transcoding /stuff/mp3/video/mythtv/1001_20150923123600.mpg done Sep 23 13:42:04 localhost mythtranscode: mythtranscode[26173]: N CoreContext? main.cpp:818 (WaitToDelete?) Transcode: delete old file: waiting while program is in use. Sep 23 13:42:04 localhost mythtranscode: mythtranscode[26173]: N CoreContext? main.cpp:850 (WaitToDelete?) Transcode: program is no longer in use. Sep 23 13:42:05 localhost mythtranscode: mythtranscode[26173]: N CoreContext? main.cpp:749 (transUnlink) Requesting delete for file 'myth://Default@servalan/1001_20150923123600.mpg.old'. Sep 23 13:42:05 localhost mythtranscode: mythtranscode[26173]: I CoreContext? mythcontext.cpp:1194 (~MythContext) Waiting for threads to exit.

mythbackend.log: Complains about a missing file, but then it uses the NUV anyway:

Sep 23 13:40:27 localhost mythbackend: mythbackend[20111]: I Transcode_5411648 jobqueue.cpp:1991 (DoTranscodeThread?) JobQueue?: Transcode Starting for "Test3 (Manual Record)":"2015-09-23 13:35:00": Autodetect (85.3 MB)

Sep 23 13:42:11 localhost mythbackend: mythbackend[20111]: E Transcode_5411648 programinfo.cpp:2358 (GetPlaybackURL) ProgramInfo?(1001_20150923123600.mpg): GetPlaybackURL: '1001_20150923123600.mpg' should be local, but it can not be found.

Sep 23 13:42:11 localhost mythbackend: mythbackend[20111]: I Transcode_5411648 jobqueue.cpp:2087 (DoTranscodeThread?) JobQueue?: Transcode Finished: "Test3 (Manual Record)":"2015-09-23 13:35:00": could not stat 'GetPlaybackURL/UNABLE/TO/FIND/LOCAL/FILE/ON/servalan/1001_20150923123600.mpg'

Watching the directory:

-rw-r--r-- 1 mythtv mythtv 89495896 Sep 23 13:40 1001_20150923123600.mpg -rw-r--r-- 1 mythtv mythtv 73929822 Sep 23 13:42 1001_20150923123600.mpg.tmp -> -rw-r--r-- 1 mythtv mythtv 73946735 Sep 23 13:42 1001_20150923123600.nuv

This makes documented functionality unusable for me, in spite of there not being any warnings about it. If the default transcoder options are likely to eat your files, this should be documented.

[toad@…]

mythbackend --version

[toad@…]

Note that this is not due to CPU usage, not having enough horsepower etc; it uses ~ 30% of one core when trying to play video (actually showing it at half speed).

This might be a duplicate of #12303, sorry.

[Stuart Auchterlonie]

Closing all old tickets in trac.

If your issue still persists, please open an issue in Github ​https://github.com/MythTV/mythtv/issues

and reference the existing trac ticket.