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• FFMPEG - Automatic Stream Copy Then Encode On Fail

  18 mars 2017, par Waverunner

  I’ve embarked on a mission to get rid of all of my MKV files since the MP4 container works better for me. So to that end, I did some research and wrote a small script that searches my data files for MKVs and stream copies them to MP4. The script works most of the time, but I get the occasional file that fails and since the script deletes the originals, I lose the file completely.

  I’d like to modify the script in two ways :

  (1) Before deleting the original file, check that the converted file is greater than zero.

  (2) If the converted file is zero (failed) then run an FFMPEG command to re-encode the original file using default values utilizing Intel Quick Sync hardware encoding, then delete the original as usual and go on to the next file in the list.

  Here’s what I have so far...

  @ECHO OFF
  
  cls
  
  echo This script automatically converts MKV video files to MP4.
  
  echo.
  
  echo Changing directory to data drive (Z:).
  
  echo.
  
  Z:
  
  echo Retrieving list of MKV files...
  
  echo.
  
  dir /b /s *.mkv > MKV-Files.txt
  
  echo MKV list compiled.
  
  echo.
  
  echo Converting files to MP4...
  
  echo.
  
  FOR /F "delims=;" %%F in (MKV-Files.txt) DO (
  
  echo Converting "%%F"
  
  echo.
  
  C:\FFMPEG\bin\ffmpeg.exe -y -i "%%F" -movflags faststart -codec copy "%%~dF%  %~pF%%~nF.mp4"
  
  echo.
  
  echo Conversion successful.
  
  echo.
  
  echo Deleting "%%F"
  
  echo.
  
  del "%%F" /F 
  
  )
  
  echo Job completed.
  
  echo.
  
  echo Exiting...

  Thanks in advance for your ideas.

• Difference between ffmpeg and avconv for rawvideo image2pipe

  15 août 2016, par NHDaly

  I’m not sure why, but avconv does not seem to be piping raw video like I would expect.

  I’m trying pipe a video from ffmpeg into python (eventually I want to read from x11grab, not a video file). It works just fine on my Macbook using ffmpeg, but when I use avconv on Debian Jessie, the stream cuts off early !

  Here’s my basic python, which is following this guide :

  input_resolution_shape = (1280,800,3)
  
  input_bytes = reduce(mul, input_resolution_shape, 1)
  
  print input_bytes
  
  
  
  # Prints 3072000
  
  
  
  import subprocess as sp
  
  command = [ FFMPEG_BIN,   # This is either "avconv" or "ffmpeg".
  
              '-i', 'test_video.mp4',
  
              '-f', 'image2pipe',
  
              '-pix_fmt', 'rgb24',
  
              '-vcodec', 'rawvideo', '-']
  
  pipe = sp.Popen(command, stdout = sp.PIPE, bufsize=10**8)
  
  
  
  import numpy
  
  for _ in range(100):  # read 100 frames
  
      # read 1280*800*3 bytes (= 1 frame)
  
      raw_image = pipe.stdout.read(input_bytes)
  
      # transform the byte read into a numpy array
  
      image = numpy.fromstring(raw_image, dtype='uint8')
  
      if image.size != 0:
  
          print image.size
  
  
  
          # Prints 1015808

  On the mac, the image.size printed is the same as the input_bytes, 3072000. But on debian, it’s 1015808. Any ideas why that could be happening ?

  Interestingly, 3072000/1015808 is just about 3 :

  In [1]:    3072000./1015808.
  
  Out[1]:    3.024193548387097

• A random pixel on a keyframe. (ffmpeg)

  5 juin 2013, par Chris Russo

  Hello folks of SO !

  We're trying to do some very small and simple code in PHP to generate a variation of a video, using always the same file.

  The script would have to make a small pixel mark, on random or specific frame of the video file, and this would have to be streamed in real time.

  Here's some pseudo code to explain my idea :

  $frame = $_GET[frame];
  
  $videofile = 'video.avi';
  
  
  
  make_random_red_pixel_mark($videofile, $frame);

  Does anyone know if this is possible using ffmpeg ? As well, it is of extreamly importance for us, to execute this procedure as fast as possible.

  A solution that would imply reprocessing the whole video, won't be useful for our purposes. It should be something like a closed caption, or a quick image / overlay filter that could be applied without an entire video reprocessing. As well, we can't put the overlay using Javascript nor any HTML approach, since the actual manipulation has to be on the video file itself.

  The quality, and framerate of the original video, should be kept intact. Perhaps some other PHP module or software that could be execute from PHP using an exec() ?

  Any recommendation ?

  Thanks in advance !!
  Chris C. Russo

  More information :

  1) It's possible for us to apply this procedure on any frame we want to, so we could use a "keyframe" in order to avoid the decoding and reencoding of an entire GOP.

  2) As previously stated, the video stream would have to flow in real time.