On Sun, 20 Jun 2021 at 13:28, <ibur...@compuscience.com> wrote: > Now I want to create a new video by extracting the part that has the > transition, with an additional second on each side, so I want to cut from 6 > to 12 and I use the following: > > Ffmpeg -ss 6 -i input.mp4 -to 6 -c copy output.mp4 > > I expect a final video with 6 seconds, showing the transition starting at 1 > and ending at 5. Instead I get a video with 9 seconds and the transition > seems to start at 5.
I'm no expert but have done similar things and this feels like it might be a 'seeking while doing a codec copy' issue. From the Wiki: > Using -ss as input option together with -c:v copy might not be accurate since > ffmpeg is forced to only use/split on i-frames. Though it will—if > possible—adjust the start time of the stream to a negative value to > compensate for that. Basically, if you specify "second 157" and there is no > key frame until second 159, it will include two seconds of audio (with no > video) at the start, then will start from the first key frame. So be careful > when splitting and doing codec copy. https://trac.ffmpeg.org/wiki/Seeking#Seekingwhiledoingacodeccopy I am happy to be corrected if off-base. Incidentally, it is good practice to post full, uncut console output when seeking help with ffmpeg usage here. Cheers, Rob _______________________________________________ ffmpeg-user mailing list ffmpeg-user@ffmpeg.org https://ffmpeg.org/mailman/listinfo/ffmpeg-user To unsubscribe, visit link above, or email ffmpeg-user-requ...@ffmpeg.org with subject "unsubscribe".
