Some decoders will handle a variety of elementary streams, you just need to feed them with proper PTS information, which is usually only available at layers above ES.
It is possible to manipulate the PTS directly with re-encoding, but there is no guarantee that the decoder you'll be playing back with can keep up. To slow down said video so that it is twice as long:įfmpeg -i source.mkv -vf "setpts=2.0*PTS" target.mkvīoth examples above will re-encode the video. To double the speed of video for your daughter's school project of baking brownies:įfmpeg -i source.mkv -vf "setpts=0.5*PTS" target.mkv But generally the options you want to look at are: -b:v, -b:a, -minrate, -maxrate, and -quality. Look at the links in References section to get examples on the knobs you can tweak. Probably you want more control than just changing the codecs. For example, to make H.264/AAC stream:įfmpeg -i source.mkv -c:v libx264 -c:a aac target.mp4įfmpeg -i source.mkv -c:v libvpx-vp9 -c:a libvorbis target.webm You need to specify video and audio codecs you want to use. Cropping Videoįfmpeg -i source.mkv -vf "crop=width:height:left:top" target.mkvĪdjust width, height, left, and top to define the rectangular area you want to extract. You can workaround that by making first sample with 0 PTS using -avoid_negative_ts make_zero.
There is also problem with discontinuous time stamps that some decoders may not like. Because most likely the frame you specified isn't a keyframe and needs I- and P-pictures to build the complete frame. The -ss option will start your stream from the closest I-picture. c copy will preserve the codec and not re-encode the bitstream, so this operation will be super fast to get a stream approximately the length you want. Cut Video To Lengthįfmpeg -i source.mkv -ss 0:00:00 -to 1:00:00 -c copy target.mkvĪdjust -ss and -to to trim video. I want to start collecting the command lines I use more than once. Not editing them, but making test streams and the utility ffmpeg has been extremely valuable. Due to my work, I work with videos often.
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