On Mon, May 2, 2022 at 7:27 AM Alexander Solonsky via ffmpeg-user < ffmpeg-user@ffmpeg.org> wrote:
> Dear Experts, > > I'm trying to split an input file into 2 second chunks, transcode and > assemble using a concat muxer. And experiencing two problems: > major one: > 1) when using ffmpeg -ss 00:00:08 -t 2 -i <input_file> -c:v libx264 .... > instead of seeking to second 8, ffmpeg seeks somewhere to second 15 or so. > The first segments are correct, and then it start to go haywire. > Using accurate seek ffmpeg -i <input_file> -ss 00:00:08 -t 2 -c:v libx264 > .... resolves the problem. But it is completely unusuble if you want to > split the whole file. > Minor one: > 2) when concatenating the resulting files - there happens a noticeable > break between the chunks. For both audio and video and is equal to 2 > additional frame durations (e.g. prev chunk ends at 1.981333 and the next > chunk (after concat) while it should start at 2.023000 actually starts at > 2.095744 for 24 fps video, and for audio prev chunk ends at 1.927256 and > starts at 2.023220 while it should start at 1.950476). > > adding all additional flags like copyts, copytb, enctimebase, vsync > doesn't change anything. And it's really curious when using the hls demuxer > - it splits the file accurately and fast, without these breaks. > > Can you please help me fix those two problems or suggest to understand > which command like I could use to reproduce splitting behavior from the HLS > demuxer? > It can not be fixed. You can not seek and start decoding without key frames. > > Thanks, > Alexander > ////////////// > > _______________________________________________ > 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".