How to crop last N seconds from a TS video

Question

Is there any way to crop the last N seconds from a video? The format is in this case 'MPEG-TS'.

With FFMPEG, I know there is an option for start time and duration, but neither of these are usable in this use case. Video can have any possible length, so the duration cannot be fixed value.

Also, the solution must run in Windows command line and can be automated.

Answer 1

The desired functionality can be achieved with the following steps:

1. Use ffmpeg to determine the length of the video. Use e.g. a cmd script:

   set input=video.ts
   
   ffmpeg -i "%input%" 2> output.tmp
   
   rem search "  Duration: HH:MM:SS.mm, start: NNNN.NNNN, bitrate: xxxx kb/s"
   for /F "tokens=1,2,3,4,5,6 delims=:., " %%i in (output.tmp) do (
       if "%%i"=="Duration" call :calcLength %%j %%k %%l %%m
   )
   goto :EOF
   
   :calcLength
   set /A s=%3
   set /A s=s+%2*60
   set /A s=s+%1*60*60
   set /A VIDEO_LENGTH_S = s
   set /A VIDEO_LENGTH_MS = s*1000 + %4
   echo Video duration %1:%2:%3.%4 = %VIDEO_LENGTH_MS%ms = %VIDEO_LENGTH_S%s
   

2. Calculate the start and end point for clip operation

   rem ** 2:00 for the start, 4:00 from the end
   set /A starttime = 120
   set /A stoptime = VIDEO_LENGTH_S - 4*60 
   set /A duration = stoptime - starttime
   

3. Clip the video. As a bonus, convert the TS file to a more optimal format, such as H.264

   set output=video.mp4
   
   vlc -vvv --start-time %starttime% --stop-time %stoptime% "%input%" 
     --sout=#transcode{vcodec=h264,vb=1200,acodec=mp3, 
     ab=128}:standard{access=file,dst=%output%} vlc://quit
   
   rem ** Handbrake has much better quality **
   handbrakeCLI -i %input% -o %output% -e x264 -B 128 -q 25 
     --start-at duration:%starttime% --stop-at duration:%duration%