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• Why the output of the ffmpeg-python doesn't match the image shape ?

  9 novembre 2019, par Swi Jason

  I used the ffmpeg-python module to convert video to images. Specifically, I used the code provided by the official git repo of ffmpeg-python, as below

  out, _ = (
  
      ffmpeg
  
      .input(in_filename)
  
      .filter('select', 'gte(n,{})'.format(frame_num))
  
      .output('pipe:', vframes=1, format='image2', vcodec='mjpeg')
  
      .run(capture_stdout=True)
  
  )
  
  im = np.frombuffer(out, 'uint8')
  
  print(im.shape[0]/3/1080)
  
  # 924.907098765432

  The original video is of size (1920, 1080) and pix_fmt ’yuv420p’, but the outputs of the above code is not 1920.

  I have figured out by myself that the output of ffmpeg.run() is not a decoded image array, but a byte string encoded by JPEG format. To restore the image into a numpy array, simply use the cv2.imdecode() function. For example,

  im = cv2.imdecode(im, cv2.IMREAD_COLOR)

  However, I can’t use opencv on my embeded Linux system. So my question now is that, can I get numpy output from ffmpeg-python directly, without the need of converting it by opencv ?

• How to use find to match substring of files to be concatted ?

  23 mars 2023, par Russell Batt

  complete beginner here, so sorry if this is painfully obvious. I'm trying to write a shell script to ffmpeg concat protocol a bunch of split video files together by looping over the files and dynamically adding the correct parts to be joined together. For example, turning this :
  

  


  titlea-00001234-01.ts
  
titlea-00001234-02.ts
  
titlea-00001234-03.ts
  
titleb-00001234-01.ts
  
titleb-00004321-02.ts
  
titleb-00004321-03.ts
  

  


  into this :
  

  


  titlea-00001234.mp4
  
titleb-00004321.mp4
  

  


  by doing this

  


  ffmpeg -i "concat:titlea-00001234-01.ts|titlea-00001234-02.ts|titlea-00001234-03.ts" -c copy titlea-00001234.mp4
ffmpeg -i "concat:titleb-00001234-01.ts|titleb-00001234-03.ts|titleb-00001234-03.ts" -c copy titleb-00001234.mp4


  


  But what I'm having trouble with is using find to add the correct parts after "concat:".

  


  Here's my best attempt :

  


  #!/bin/bash
for i in /path/to/files/*.ts
    do
        if [[ "$i" =~ (-01) ]]
        then
            j="${i##*/}"
            k="${j%-0*}"
            ffmpeg -i `concat:( find /path/to/files/ -type f -name "{$k}*" -exec printf "%s\0" {} + )` -c copy /path/to/output/"{$k%.ts}.mp4"
        else
            echo "no files to process"
            exit 0
        fi
    done


  


  But this gives an error of "No such file or directory".

  
Edit This solution worked perfectly for my needs https://stackoverflow.com/a/75807616/21403800 Thanks @pjh and everyone else for taking the time to help

  


• avcodec/simple_idct_template : change the idct coefficients so that they match the...

  12 janvier 2014, par Michael Niedermayer

  avcodec/simple_idct_template : change the idct coefficients so that they match the x86 code
  no changes in either standard deviation or PSNR is seen in any of the changed fate
  
  cases
  MSE changes from 0.05012422 to 0.04890000
  Signed-off-by : Michael Niedermayer <michaelni@gmx.at>
  

  • [DH] libavcodec/simple_idct_template.c
  • [DH] tests/ref/fate/prores-422
  • [DH] tests/ref/fate/prores-422_hq
  • [DH] tests/ref/fate/prores-422_lt
  • [DH] tests/ref/fate/prores-422_proxy
  • [DH] tests/ref/fate/prores-alpha
  • [DH] tests/ref/fate/prores-alpha_skip
  • [DH] tests/ref/fate/prores-transparency
  • [DH] tests/ref/fate/prores-transparency_skip
  • [DH] tests/ref/vsynth/vsynth1-dnxhd-720p-10bit
  • [DH] tests/ref/vsynth/vsynth1-prores
  • [DH] tests/ref/vsynth/vsynth1-prores_ks
  • [DH] tests/ref/vsynth/vsynth2-dnxhd-720p-10bit
  • [DH] tests/ref/vsynth/vsynth2-prores
  • [DH] tests/ref/vsynth/vsynth2-prores_ks