[FFmpeg-user] ffmpeg with damaged dv from tape capture

Dave Rice dave at dericed.com
Fri Mar 8 23:23:43 CET 2013

On Mar 8, 2013, at 4:42 PM, Carl Eugen Hoyos wrote:
> Dave Rice <dave <at> dericed.com> writes:
>> I uploaded a 60 second sample here
> Thank you for the sample, I opened ticket #2340!
> (Since you know much more about dv than I do, feel 
> free to add the missing information.)

Looks accurate. I've tried to read through the dv demuxer to understand this error:
[dvvideo @ 0x317f860] AC EOB marker is absent pos=64
but don't quite understand how an occurrence of this error affects the demuxing or cause different durations of audio and video to output per frame.

> But didn't you originally report another issue?
> One where no audio was detected in a raw dv stream?

Yes. In that case my initial frame contained audio DIF blocks with error codes and ffmpeg interpreted the whole stream as only a video track with no audio. In this case the frame with audio errors is in the middle and causes ffmpeg to export less than 1/(30000/1000) second of audio for the frame and there is loss of sync. 

> [...]
>> I tested the same file in mplayer and it also 
>> loss sync at the same point. 
> mplayer -demuxer rawdv works fine.

Works fine for me too, but without -demuxer rawdv there is a loss of sync similar to with ffmpeg. Does mplayer have more than one dv demuxer with rawdv being a non-default one. Is there a comparable rawdv demuxer for ffmpeg?

Dave Rice

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