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• Bash script for splitting video using ffmpeg outputs wrong video lengths

  19 juin 2018, par jonny

  I have a video that’s x seconds long. I want to split that video up into equal segments, where each segment is no longer than a minute. To do that, I cobbled together a fairly simple bash script which uses ffmprobe to get the duration of the video, find out how long each segment should be, and then iteratively split the video up using ffmpeg :

  INPUT_FILE=$1
  
  INPUT_DURATION="$(./bin/ffprobe.exe -i "$INPUT_FILE" -show_entries format=duration -v quiet -of csv="p=0")"
  
  
  
  NUM_SPLITS="$(perl -w -e "use POSIX; print ceil($INPUT_DURATION/60), qq{\n}")"
  
  
  
  printf "\nVideo duration: $INPUT_DURATION; "
  
  printf "Number of videos to output: $NUM_SPLITS; "
  
  printf "Approximate length of each video: $(echo "$INPUT_DURATION" "$NUM_SPLITS" | awk '{print ($1 / $2)}')\n\n"
  
  
  
  for i in `seq 1 "$NUM_SPLITS"`; do
  
      START="$(echo "$INPUT_DURATION" "$NUM_SPLITS" "$i" | awk '{print (($1 / $2) * ($3 - 1))}')"
  
      END="$(echo "$INPUT_DURATION" "$NUM_SPLITS" "$i" | awk '{print (($1 / $2) * $3)}')"
  
  
  
      echo ./bin/ffmpeg.exe -v quiet -y -i "$INPUT_FILE" \
  
      -vcodec copy -acodec copy -ss "$START" -t "$END" -sn test_${i}.mp4
  
  
  
      ./bin/ffmpeg.exe -v quiet -y -i "$INPUT_FILE" \
  
      -vcodec copy -acodec copy -ss "$START" -t "$END" -sn test_${i}.mp4
  
  done
  
  
  
  printf "\ndone\n"

  If I run that script on the 30MB / 02:50 duration Big Buck Bunny sample from here, the output of the program would suggest the videos should all be of equal length :

  λ bash split.bash .\media\SampleVideo_1280x720_30mb.mp4
  
  
  
  Video duration: 170.859000; Number of videos to output: 3; Approximate length of each video: 56.953
  
  
  
  ./bin/ffmpeg.exe -v quiet -y -i .\media\SampleVideo_1280x720_30mb.mp4 -vcodec copy -acodec copy -ss 0 -t 56.953 -sn test_1.mp4
  
  ./bin/ffmpeg.exe -v quiet -y -i .\media\SampleVideo_1280x720_30mb.mp4 -vcodec copy -acodec copy -ss 56.953 -t 113.906 -sn test_2.mp4
  
  ./bin/ffmpeg.exe -v quiet -y -i .\media\SampleVideo_1280x720_30mb.mp4 -vcodec copy -acodec copy -ss 113.906 -t 170.859 -sn test_3.mp4
  
  
  
  done

  As the duration of each partial video, i.e. the time between -ss and -t, are equal for each subsequent ffmpeg command. But the durations I get are closer to :

  test_1.mp4 = 00:56
  
  test_2.mp4 = 01:53
  
  test_3.mp4 = 00:56

  Where the contents of each partial video overlap. What am I missing here ?

• cutting with ffmpeg, video got wrong colors and pixaleted frames

  21 mai 2023, par Piroclasyer Pinyo

  after cutting and Concatenate with ffmpeg i- example.mp4 -ss 01:02 -to 03:01 -vcodec copy -acodec copy output.mp4, it looks like the video changed resolution at some time and got wrong colors and pixaleted frames, source file was deleted, is it possible to repair it extracting the raw data ?

  


  I tried to use the -vf scale filter of ffmpeg to see if it gets other results, but stills the same.

  


  using ffmpeg -fflags +igndts i got "Non-monotonous DTS in output stream 0:1 ; previous : 399777, current : 399767 ; changing to 399778. This may
result in incorrect timestamps in the output file."

  


  image with the result

  


• Convertion of mp3 file with ffmpeg results in a file with wrong length [duplicate]

  16 avril 2018, par Arthur Efixty

  This question already has an answer here :

  • ffmpeg : add subtitles to mp4 with out creating a new file
    
    1 answer
    

  I wrote a simple script for Linux where I loop through the folder (containing only .mp3 files) and add an album art to every item.

  Here is my code :

  for file in ~/Desktop/Rise\ Against/*
  
      do
  
          ffmpeg -i "${file}" -i ~/Desktop/appeal\ to\ reason.jpeg -map 0:0 -map 1:0 -codec copy -id3v2_version 3 \-metadata:s:v title="Album cover" -metadata:s:v comment="Cover (front)" "${file%}";
  
      done

  If I set the output filename to hardcoded value like out.mp3 then it works fine. But I need these files to have the same name as existing and overwrite them.

  Running this script results in having all files edited as expected (the album art changed) but they all have a length of 3 seconds. In terminal I get this [mp3 @ 0xc695e0] Audio packet of size 378219 (starting with 6B0855F2...) is invalid, writing it anyway.

  Thanks in advance !