Thanks for the answer. But I want to do the same thing like the person from the mailing list. I want that ffmpeg cuts the video in specific segments for DASH with variable durations. I want to extract this information and use it to cut the video again using different qualities. I could use the -map command for directly encoding different qualities but I want to outsource the workload. I want to be sure that everything is aligned.
The one person from the mailing list said: > In this particular case, you can easily work around the floating point > rounding issues, since the rounding behaviour of -force_key_frames is > specified: "more precisely at the first frames after each specified time". > You just have to make sure your timestamps are rounded down. For example, > with 24000/1001 FPS: 4.21 4.25 4.30* 4.34 4.38, you need to write 4.29, not > 4.30, but you can also write any value between 4.25425 and the actual > 4.295958333. (4.25+4.30)/2 = 4.275 should always work. This looks a bit like a workaround to me. Frame numbers look more precise for me. I do not understand why frame numbers should not be aligned except the frame rate is changing. On 2/16/19 8:52 AM, Gyan wrote: > > > On 16-02-2019 05:03 AM, Nick wrote: >> Hi, >> why was the "Modified force_key_frames option to accept frame numbers" >> (2014) declined? >> >>> https://ffmpeg.org/pipermail/ffmpeg-devel/2014-November/165167.html >> You can even specify frame numbers in the current ffmpeg version using: >>> -force_key_frames expr:gte(n,n_forced*96) >> Using a framerate of 24 means a keyframe every 4s. >> I think it is very useful to have something like >> >>> /force_key_frames n:0,25,50,75,100/ > > For a regular pattern like that one, you can already use > > -force_key_frames expr:not(mod(n,25)) > > Expressions are be evaluated using the interface documented at > https://ffmpeg.org/ffmpeg-utils.html#Expression-Evaluation > > > Gyan > _______________________________________________ > ffmpeg-user mailing list > [email protected] > http://ffmpeg.org/mailman/listinfo/ffmpeg-user > > To unsubscribe, visit link above, or email > [email protected] with subject "unsubscribe". _______________________________________________ ffmpeg-user mailing list [email protected] http://ffmpeg.org/mailman/listinfo/ffmpeg-user To unsubscribe, visit link above, or email [email protected] with subject "unsubscribe".
