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• How do I use ffmpeg to extract the total time of a video slice without actually producing the video slice ?

  18 juin 2022, par iChux

  


  I have a video named 'ev.mp4'. Slice the video into segments :

  


  


  # COMMAND 1
ffmpeg -i "ev.mp4" -c copy -map 0 -segment_time 15 -g 9 \
    -sc_threshold 0 -force_key_frames "expr:gte(t,n_forced*9)" \
    -reset_timestamps 1 -f segment ev-%04d.mp4

ev-0000.mp4
ev-0001.mp4
ev-0002.mp4


  


  


  Get each segment time

  


  


  # COMMAND 2
for f in ev-*.mp4;
do
    echo $f == $(ffprobe -v error -show_entries \
    format=duration -of default=noprint_wrappers=1:nokey=1 $f);
done;

ev-0000.mp4 == 17.251000
ev-0001.mp4 == 17.918000
ev-0002.mp4 == 10.444000


  


  


  I am only able to extract the duration of each sliced segment after the videos have existed in a sliced format on the hard drive e.g. ev-0000.mp4

  


  


  My question : is it possible to get the duration of each slice from COMMAND 1 such that instead of producing the sliced files, I will get the duration of each slice ?

  


• Slice video with ffmpeg at a SCTE 35 Marker or at a PTS value

  2 juin 2022, par Henk

  I would like to slice a video at a specific scte 35 marker or at a PTS value of the Marker itself ?
or even better if i could get a command to get a specific frame at a specific PTS value(for FFmpeg).

  


  The PTS of the scte35 marker we have is : 4,878,195,990 so we need the frame of exactly that PTS, i have tried it with FFmpeg but it seams like ffmpeg starts the video at 0 PTS and not the original start PTS 4,860,613,590, analyzing it in DVB analyzer we see the SCTE35 marker at that PTS but cannot view the frame.

  


  the reason for this is we have an output chunk that we got the keyframes for and we want to make sure the the input is sliced at the correct place on where the scte35 is placed.

  


  So your help will be much appreciated

  


• Slice audio with ffmpeg with high precision

  4 mai 2022, par rap-2-h

  I want to slice an audio file of 2.790703 seconds in four equal parts with ffmpeg. To get the total duration I run :

  


  ffprobe -v error -show_entries format=duration -of default=noprint_wrappers=1:nokey=1 dl.wav


  


  If I divide 2.790703 by 4, the result is : 0.69767575. Then if I try to cut from 0 to 0.69767575 :

  


  ffmpeg -i dl.wav -acodec copy -ss 0.0 -t 0.69767575 -y dltest.wav


  


  Then I get the duration (it should be 0.69767575) I get 0.719819 :

  


  ffprobe -v error -show_entries format=duration -of default=noprint_wrappers=1:nokey=1 dltest.wav


  


  Why is this inaccurate ? Can I have a slice of 0.69767575 instead of 0.719819 ?