On 9/10/22, Cecil Westerhof via ffmpeg-user <ffmpeg-user@ffmpeg.org> wrote: > Cecil Westerhof via ffmpeg-user <ffmpeg-user@ffmpeg.org> writes: > >> Paul B Mahol <one...@gmail.com> writes: >> >>> On 9/10/22, Cecil Westerhof via ffmpeg-user <ffmpeg-user@ffmpeg.org> >>> wrote: >>>> I have to concatenate about 30 videos together with xfade. Because I >>>> did not mange to find a way to do that in one command I wrote a script >>>> that does 1 and 2 to 1-2, 3 and 4 to 3-4, 4 and 5 to 5-6, … >>>> Then 1-2 and 3-4 to 1-4, 5-6 and 7-8 to 5-8, … >>>> Etcetera. >>>> >>>> But it seems that in every iteration the audio goes out of sync with >>>> about one second. >>>> >>>> Example of one of the commands: >>>> nice -n 10 ionice -c3 time ffmpeg -y \ >>>> -i snellerDanDeWind.mkv \ >>>> -i deFinale.mkv \ >>>> -vcodec libx264 \ >>>> -crf 26 \ >>>> -acodec libmp3lame \ >>>> -qscale:a 9 \ >>>> -preset veryfast \ >>>> -filter_complex >>>> >>>> 'xfade=transition=slidedown:duration=4:offset=126.083000;acrossfade=d=4' >>>> \ >>> >>> Offset should be first video duration minus xfade duration. >>> Assuming that audio is not longer than video. >> >>>> DURATION : 00:02:10.083000000 >> >> But that is the case. >> 02:10.083000000 -> 130.083 >> 130.083 - 4 = 126.083 >> >> Audio and video off the first file are the same. >> Strangely the video of the second file is 0.44 seconds longer as the >> audio. But that should not be a problem? > > Strangely enough I see that in several of the videos the length of the > video and audio is not the same. But they where all cut with ffmpeg > out of a bigger one with something like: > ffmpeg -y \ > -ss $1 -to $2 \ > -i ${input} \ > -pix_fmt yuv420p \ > -vcodec libx264 \ > -crf 26 \ > -preset veryfast \ > $3.mkv >
Video needs to be constant frame rate pts without gaps. Audio must have constant sample rate & channels and no pts gaps. The only correct way to get audio duration is to count audio samples, with astats filter. > -- > Cecil Westerhof > Senior Software Engineer > LinkedIn: http://www.linkedin.com/in/cecilwesterhof > _______________________________________________ > 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". > _______________________________________________ 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".