[mythtv-users] Stuttering and loss of sync after transcoding some recordings

[Per Öberg]

Can someone suggest a good way to debug this myself?

Is there any logs for the mythtranscode that are more detailed than the 
error code? (which is only available after a complete failure?)

I am thinking of saving the original file, as per myth-option, and then 
doing a post-processing of the transcoded file to check for errors and 
thereafter removing the original. Can I do this as a regular job or will 
the backend wonder what happened to the original file? (Or if i remove 
the erroneously transcoded copy will the backend wonder about where that 
went?)

Best regards
Per Öberg


Per Öberg wrote:
> In Sept 29 Peter Scahchte reported problems with mythtranscode for some 
> recordings.
> 
> http://www.gossamer-threads.com/lists/mythtv/users/351511?do=post_view_threaded 
> 
> 
> I have the exact same problem but I didn't manage to find any solution. 
> The problem is that occasionally transcoded recordings
> (MPEG2 from DVB-T transcoded to MPEG 4) become damaged so that at some 
> point in the recording the sound starts to stutter and mythtranscode 
> never recovers. The playback is out of sync 1-2s and mythfrontend spits 
> out loads of "WriteAudio: buffer underrun" messages.
> 
> In my opinion it seems like the video is slowed down while the audio 
> keeps the same rate so that the audio buffer is emptied before the video 
> buffer and for this reason there is not enough data to play sound for 
> the whole interval, hence the stutter.
> 
> xine, mplayer and vlc all give different errors at the same stream 
> position so there is definitely something wrong with the file. Sometimes 
> the errors occur right after a commercial break but sometimes it's in 
> the middle of the program. Some channels seem to be more error prone and 
> some channels seems to be immune. I have two cards but I haven't managed 
> to find any correlation with card number.
> 
> As with Peter I did not experience this in 0.20. My system is Gentoo on 
> an AMD64 with mythtv-0.21_p18116.
> 
> 
> Best regards, and thanks for any help
> Per Öberg
> 
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