On 6/17/20, Rob Hallam <[email protected]> wrote: > On Wed, 17 Jun 2020 at 11:34, Paul B Mahol <[email protected]> wrote: > >>> ie neither should change the length of the inputs they operate on. >>> >>> Is that a mistaken assumption perhaps? > >> Yes, very mistaken. > >> Duration of output is first input duration + second input duration - >> duration of transition. >> For xfade you need to set offset, acrossfade does not need that. > > D'oh, of course! Mistake on my part, I hadn't had my morning coffee. > Thanks for keeping me right. > > What I meant was that they should both result in equal duration, > **if overlap is set in acrossfade**. Is that a safe assumption? > > From the docs: > >> overlap, o >> Should first stream end overlap with second stream start. Default is > enabled. > https://ffmpeg.org/ffmpeg-filters.html#acrossfade > > Also, from your earlier suggestion: > >> I believe this two should be - 2 seconds instead. Because both >> transition durations for two xfade and acrossfade filters is 2 >> seconds. > > An offset of -2 produced desynched audio in the second segment (input > 1 in the original filtergraph). The closest I can get to synch is an offset > of -1 for the first input and -2 for the second; but it's still a little > off. > > I'll try to create an example using generated 1Hz chirps and > 'showspectrum'. If I can replicate there I will post a bug as you > suggested. >
First try single xfade and acrossfade combination. For second xfade you will obviously need to substitute 2 seconds from output of first xfade transition. > Cheers, > Rob > _______________________________________________ > ffmpeg-user mailing list > [email protected] > https://ffmpeg.org/mailman/listinfo/ffmpeg-user > > To unsubscribe, visit link above, or email > [email protected] with subject "unsubscribe". _______________________________________________ ffmpeg-user mailing list [email protected] https://ffmpeg.org/mailman/listinfo/ffmpeg-user To unsubscribe, visit link above, or email [email protected] with subject "unsubscribe".
