ffmpeg how to cut off video and keep subtitles

[aeon1]

I need to cut off 3 seconds from the end of video and keep all subtitle streams, but it does not work.

video length: 1:33:34

ffmpeg -ss 0:00:00 -t 1:33:31 -i 111.mp4 -c copy 1111.mp4
ffmpeg -ss 0:00:00 -t 1:33:31 -i 111.mp4 -map 0:s -c copy 1111.mp4

[Budman1]

FFmpeg is accurate when it comes to cutting videos but you have to understand its method. You get a different result if you specify your -ss and -t before the video name or after it. You will get the closest results if you specify both after the -i video. This is because FFMpeg must cut on a Key frame or 'I' frame. If you ask it to start somewhere in between 'I' frames it will start there but usually gives a static frame until it meets a new key frame.

Close Method

ffmpeg -i 111.mp4 -ss 0 -t 1:33:31 -c copy 1111.mp4

FFmpeg can also use total seconds:

ffmpeg -i 111.mp4 -ss 0 -t 5611 -c copy 1111.mp4

You can get even closer if you specify the number of frames:

ffmpeg -i 111.mp4 -ss 0 -vframes <xxxxxxxxx> -c copy 1111.mp4

If you specify time BEFORE the -i video, ffmpeg will seek to the key frame BEFORE the start point. If you specify time AFTER the -i video, it will seek to the Key Frame AFTER the cut point. It also likes to end on a non- 'B' Frame so your end point may not be exact. If you use the -vframes method FFMpeg will throw a 'P' frame at the end if needed as close as it can to your cut point.

[Budman1]

Notice in the example below, the end cut is made 1 frames in front of the 'P' frame 14176 because FFMpeg usually requires 1 frame to stop.

ffmpeg -ss 0.000000 -i "C:\Users\Bud\Desktop\cgop.mp4" -vframes 14176 -c:v copy -c:a copy -y "C:\Users\Bud\Desktop\3_0_cgop.mp4"

The above string will cut from time 0.000000 through 447.985342 exactly


[Attachment 54283 - Click to enlarge]

[aeon1]

Hi Budman1,

Perhaps I did not express myself clearly.

This method cuts video exactly as it should(3 seconds form the end) but does not keep subtitle streams.

ffmpeg -ss 0:00:00 -t 1:33:31 -i 111.mp4 -c copy 1111.mp4

What you suggest...

ffmpeg -i 111.mp4 -ss 0 -t 1:33:31 -c copy 1111.mp4

...does not work , it cuts 3 seconds of video from the beginning, audio is playing and removes subtitles.


My problem is not the cut itself, but how to convince ffmpeg not to remove subtitles.

[Budman1]

Make sure you have latest ffmpeg and then:
FFMpeg -i 111.mp4 -ss 0 -t 1:33:31 -c copy -map 0:0 -map 0:1 -map 0:2 1111.mp4

Works for me here.

[aeon1]

The problem was with the older version of ffmpeg, the new one works well.