[Ffmpeg-devel] A problem with timestamps on quicktime movies

[Baptiste Coudurier]

Y S Sean Lee wrote:
> Hi,
> 
> I have been trying to transcode a quicktime movie file to an flv format
> using
>   
>   $ ffmpeg -i Demo_FlagOfOurFathers.mov Demo_FlagOfOurFathers.flv
> 
> .
> 
> The file is a 7 second movie according to the binary reading of the
> file. I used http://developer.apple.com/documentation/QuickTime/QTFF/qtff.pdf to
> read the binary file. Apple's quicktime player also recognises the file as
> a 7 second movie.
> 
> This file seems to have one video stream, one audio stream and one data
> stream.
> 
> The length of the video stream is 11 seconds but the frames in the first four
> seconds are not to be transcoded nor to be displayed. I suppose that they exist
> just for the referencing purpose. That is, even if the length of the video
> stream is 11 seconds, the frames are to be laid between the timestamp -4
> sec and the timestamp 7 sec, and the frames between the timestamp -4 and the
> timestamp 0 are not to be transcoded.
> 
> The length of the audio stream is 7 seconds.
> 
> However, FFmpeg is not aware of this, recognises the movie as an 11
> second movie, and transcodes every frame. Consequently, the transcoded
> movie has extra frames visible at the beginning of the movie and its a/v
> sync becomes awkward.
> 
> I have uploaded the file on
> 
> ftp://upload.mplayerhq.hu/MPlayer/incoming/seanl_QuicktimeTimeStampProblem/
> 
> You can easily tell what is wrong by playing the original file and the transcoded
> file using mplayer.
> 
> I always appreciate your support and effort to make ffmpeg powerful and
> bug-free.
> 
> Thank you..
> 

That file contains edit list, which stats at 9500/2400(~ 3.96s).

ffmpeg does not support it atm. If you want to implementing it, feel
free to do so.

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