85.17 Video Trim and Cut

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This section deals with the extraction of time extents of the video, that is, to trim or to cut the video. If you are wanting to crop the video image itself throughout a video see Section 85.9. To cut a section out of a video, cut the video into two sections, pre and post the part to be cut, then concat the two parts together as explained in Section 85.3.

Using ffmpeg we can extract a segment from a video file input.mp4 (identified as the input using -i) starting at the location 7 minutes and 41 seconds from the beginning using -ss and ending at the 53 minute mark from the beginning of the video using -to.

$ ffmpeg -i input.mp4 -ss 00:07:41 -to 00:53:00 cut.mp4

The audio stream can also be synchronised at the beginning of the output stream to match the timestamp using -async 1.

$ ffmpeg -i input.mp4 -ss 00:07:41 -to 00:53:00 -async 1 cut.mp4

The process will undertake a re-encoding of the video and can take some time. To avoid the re-encoding use the -c copy command to ensure that the video is simply copied rather than re-encoding the video.

$ ffmpeg -i input.mp4 -ss 00:07:41 -to 00:53:00 -async 1 -c copy cut.mp4

By replacing -to with -t the output will be truncated after the specified duration.

$ ffmpeg -i input.mp4 -ss 00:07:41 -t 00:45:19 -async 1 -c copy cut.mp4

If -t is specified prior to -i (the input) then the duration refers to the input video rather than the output video. That is, it specifies the duration from the beginning of the input video.

Using avisplit we can also extract a particular section of an avi file (specified as the -input file) and using -t to specifiy the starting point and the end point (starting at 7 minutes and 20 seconds into the video and stopping at 8 minutes and 20 seconds in, respectively):

$ avisplit -i a.avi -t 0:7:20.0-0:8:20.0

Other Options

A graphical interface to trim a video is Video Trimmer which is installable as a FlatPack.



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