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• Resize video to same size

  5 septembre 2018, par Max Grigoriev

  I have a list of video files with different resolutions. And I should to change them to 1920x1080. It’s easy to make using ffmpeg and scale filter but result video is wrong aspect ratio. If I use aspect ratio then output resolution isn’t fullhd. Is it possible to change resolution to best available like scale="’if(gt(a,16/9),1920,-1)’ :’if(gt(a,16/9),-1,1080)’"
  and all remaining space is filled in black color ?

• Monitoring GPU usage by FFMPEG

  29 septembre 2018, par Sam Radhakrishnan

  I have an small http server which receives requests to process some video clips. The server spawns a child process and uses FFMPEG for this. I recently compiled FFMPEG to use GPUs. I am using an Nvidia GeForce GTX 1080.

  However I am unable to figure out a way to analyse the memory and other usage statistics of GPUs. I have tried nvidia-smi, but it seems to return 0% always.

  The question I have is what are some of the best tools that are available for monitoring GPU usage.

  Edit - I am on Ubuntu 16.04 and only have remote access. So command-line tools are better.

• How can I read all the data from a pipe and prevent it from closing ?

  23 septembre 2014, par slhck

  I’m trying to read raw YUV data from a compressed file using ffmpeg and pipes with Python.
  The ffmpeg command correctly spits out frames as raw YUV data, and I’m reading it like this :

  def read_from_pipe(pipe, amount):
  
      raw = pipe.stdout.read(amount)
  
      pipe.stdout.flush()
  
      return raw
  
  
  
  pipe_ref = subprocess.Popen('ffmpeg -i "' + input + '" -r 30 -c:v rawvideo -pix_fmt yuv420p -an -f rawvideo -t 5 -', 
  
    shell = True, 
  
    stdout = subprocess.PIPE, 
  
    bufsize=1920*1080*3*2)
  
  
  
  frame_num = 0
  
  while True:
  
      data = read_from_pipe(pipe_ref, width*height*3)
  
  
  
      # no more data
  
      if (len(data) != width*height*3))
  
          return results
  
  
  
      image = extract_image_data(data, width, height)
  
      # do something with image, put it into "results" and print frame / SSIM values to console
  
      frame_num += 1

  The problem is, as soon as ffmpeg is done converting all frames, my program stops. Since the program is a little slower than ffmpeg, it will stop receiving data and exit.

  Basically, for example, I can only work up to frame 30, then ffmpeg finishes at frame 60, and my program also exits. The command line output would say :

  Frame=25 SSIM=0.990472732391
  
  Frame=26 SSIM=0.98359411819
  
  Frame=27 SSIM=0.981074433586
  
  Frame=28 SSIM=0.97850843075
  
  frame=   60 fps= 27 q=0.0 Lsize=  182250kB time=00:00:02.00 bitrate=746496.0kbits/s dup=12 drop=0    
  
  video:182250kB audio:0kB subtitle:0 data:0 global headers:0kB muxing overhead 0.000000%
  
  Frame=29 SSIM=0.977698849804
  
  frame=   60 fps= 27 q=0.0 Lsize=  182250kB time=00:00:02.00 bitrate=746496.0kbits/s dup=12 drop=0    
  
  video:182250kB audio:0kB subtitle:0 data:0 global headers:0kB muxing overhead 0.000000%

  How can I get it to work on all frames that are output by ffmpeg ? Or is there any other easier way of obtaining the raw YUV data from any file if not through a pipe ? (I need it to work concurrently)