[FFmpeg-devel] hundred bucks to fix FLV cutting

Reimar Döffinger Reimar.Doeffinger
Wed Jul 18 00:15:55 CEST 2007

On Mon, Jul 16, 2007 at 03:22:08PM -0400, Cyrus A wrote:
> I'm trying to cut a small portion out of a larger FLV file. I have an 
> FLV file that is 156 seconds long. The command...
> ffmpeg -ss 6 -t 100 -y -vcodec copy -acodec copy -i 
> /home/cyrus/Desktop/test.flv /home/cyrus/Desktop/cut.flv
> ...should create a file that is 94 seconds long (seeking 6 seconds, 
> duration for 100 seconds). Instead, it creates a file 150 seconds long. 
> That is, it seems to be seeking for 6 seconds, then giving me the rest 
> of the clip. Any ideas why that's happening?

Well, to ffmpeg it looks like everything is working right, the problem
> Output #0, flv, to '/home/cyrus/Desktop/cut.flv':
>   Stream #0.0: Video: flv, yuv420p, 480x384, q=2-31, 1000.00 fps(c)

I think this will also create an output file with A-V sync that is
extremely of, but in your case with a real framerate of 15, it takes
1000 seconds of video before ffmpeg things 15 have actually passed.
I guess the frame rate is not actually know at the point where ffmpeg
sets it for the output file. I don't know why specifying -r 15
explicitly does not help.

Reimar D?ffinger

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