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• ffmpeg converting PCM data file to wav file getting distorted(noisy) data

  3 janvier 2015, par Mahendra

  I have raw pcm data in following form :

  0000 0000 0000 0000 0000 0000 0000 0000
  
  0000 0000 0000 0000 0000 0000 0000 0000
  
  0000 0000 0000 0000 0000 0000 0000 0000
  
  0000 0000 0000 0000 0000 0000 0000 0100
  
  0000 0000 0000 0000 0000 0000 0000 0000
  
  0000 0100 0100 0000 0000 efbf bdef bfbd
  
  0000 efbf bdef bfbd efbf bdef bfbd efbf
  
  bdef bfbd efbf bdef bfbd efbf bdef bfbd
  
  efbf bdef bfbd efbf bdef bfbd 0000 efbf
  
  bdef bfbd 0000 efbf bdef bfbd efbf bdef
  
  bfbd 2900 efbf bdef bfbd 0000 efbf bdef
  
  bfbd efbf bdef bfbd efbf bdef bfbd 0000

  and I want to make this data in wav file when I am converting by ffmpeg getting noisy data by this command :

  sox -V -t raw -b 16 -e signed -r 16000 -c 1 14_32_7_187.pcm  new.wav

  and :

  ffmpeg -f s16le -ar 16000 -ac 1 -i 14_32_7_187.pcm -ar 16000 -ac 1 oout.wav

  using both getting noisy data.

• FFMPEG : How to save the effects (blur, adding image , ...) on the input video instead of creating a one ?

  9 juillet 2016, par Drupalist

  I need to save the effects on the current video instead of creating a one. For example this code

  ffmpeg -i input.mp4 -i logo.png -filter_complex "[1:v][0:v]scale2ref=(505/384)*ih/8:ih/8[wm][base];[wm]setsar=1[wmsar];[base][wmsar]overlay=10:10" -pix_fmt yuv420p -c:a copy output.mp4

  pastes an image on a video, but I need the image to be pasted to input.mp4 not output.mp4.

  I tried

  ffmpeg -i input.mp4 -i logo.png -filter_complex "[1:v][0:v]scale2ref=(505/384)*ih/8:ih/8[wm][base];[wm]setsar=1[wmsar];[base][wmsar]overlay=10:10" -pix_fmt yuv420p -c:a

  but it didn’t work.

  Thanks in advance.

• I am trying to save frames from a webcam via Python and ffmpeg, but the video becomes way to fast

  10 mai 2022, par Matthias

  I get a stream of cv2 images from my webcam and want to save it to a video file. After playing a bit with cv2.VideoWriter() it turned out that using ffmpeg would provide more options and - apparently, following a few threads here on SO - lead to better results. So I gave the VidGear Python library a try, and it seems to work fine.

  


  There is one catch though : My webcam provides a variable framerate, most of the time between 10 and 30 FPS. When saving these frames the video file becomes way too fast, like watching in fast-forward. One real-time minute becomes only a few seconds in the video.

  


  I tried to play with various combinations of the ffmpeg's -framerate and/or -r parameters, but without luck. Here is the command I am using right now :

  


  ffmpeg -y -f rawvideo -vcodec rawvideo -s 1920x1080 -pix_fmt bgra -framerate 25.0 -i - -vcodec libx265 -crf 25 -r 25 -preset fast 


  


  For the records, I am creating the WriteGear class from the VidGear library like this :

  


  video_params = {
    "-vcodec": "libx265",
    "-crf": 25,
    "-input_framerate": 25,
    "-r": 25,
}
WriteGear(output_filename=video_file, logging=True, **video_params)


  


  Any ideas what I am doing wrong here and how I need to call ffmpeg ?