[FFmpeg-user] Reducing seek time when start time offset (-ss) is large

Robert Krüger krueger at lesspain.de
Fri Aug 10 21:28:55 CEST 2012


On Fri, Aug 10, 2012 at 8:42 PM, Curtis Miller <CMiller86 at gmail.com> wrote:
> This is in reply to an old thread:
> http://ffmpeg-users.933282.n4.nabble.com/Reducing-seek-time-when-start-time-offset-ss-is-large-td1460307.html
> I tried to post my reply through nabble but my mailing list subscription
> through it doesn't seem to be working.
> I'm cutting hundreds of clips from long video files and the larger the seek
> time, the longer it takes to cut a clip. I can cut a clip from the start of
> a video in about 0.5 seconds and it takes 18 seconds to cut the same length
> clip 22 minutes in. The solution in the earlier thread was to use the copy
> option for the codecs but when I use them, my video and audio is out of
> sync in the resulting files.
> My video clips are cut pretty precisely, for example, -ss 00:22:12.540 -t
> 4.32 which might have something to do with the audio sync issue when using
> copy.
> I've tried to cut multiple clips in an single encode but ffmpeg doesn't
> accept multiple -ss values. Is there an alternative method to speed up
> ffmpeg when using -ss or a way to prevent the audio and video from
> unsyncing?
> Thanks,
> Curtis

I suggested this:


on the ffmbc list for the exact same problem (if I understand your
posting correctly). Not a pretty solution but for use cases like yours
(and mine) it does the job. I was going to make a patch against ffmpeg
before posting this here but have not had time yet to do it but I'll
try to do that in the next few days. I hope this is at least going to
get a discussion about this started because I think this may be a
practical problem many people have.



More information about the ffmpeg-user mailing list