Newest 'ffmpeg' Questions - Stack Overflow

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• FFMPEG global pattern multiple input formats

  8 mars 2017, par Herman Yanush

  I need to get thumbnails of all images in the directory. Images have formats .png .jpg .JPG.

  In order to do that I use ffmpeg -pattern_type glob -i '*.jpg' -vf scale=320:-1 compressed/img%03d.png

  When I use for it *.jpg and then for *.JPG the first images are overwritten because numeration starts from zero again.

  I am looking for a way how to do a conversion for multiple formats or just for all files in the directory.

• symbol lookup error with FFmpeg

  8 mars 2017, par Tobias Geiselmann

  I am writing a Java application which uses FFmpeg. Therefore I use JNI to execute some native code. Compiling my shared object works without problems, but when I execute my code I get the following error:

  /usr/local/jamaica-6.3-1/target/linux-x86_64/bin/jamaicavm_bin: symbol lookup error: /home/tobi/workspace/sender/lib/libsender.so: undefined symbol: av_frame_alloc
  

  av_frame_alloc is a method of FFmpeg's libavutil library. I linked my shared object against a few FFmpeg libraries (such as libavcodec, libavutil, etc.), but I'm not able to execute methods from libavutil. When I run the nm command to list all the symbols from the object file, I get the following result:

  tobi@tobi:~/workspace/sender/lib$ nm libsender.so 
               U avcodec_alloc_context3@@LIBAVCODEC_54
               U avcodec_copy_context@@LIBAVCODEC_54
               U avcodec_find_decoder@@LIBAVCODEC_54
               U avcodec_find_encoder@@LIBAVCODEC_54
               U avcodec_open2@@LIBAVCODEC_54
               U av_dump_format@@LIBAVFORMAT_54
               U avformat_find_stream_info@@LIBAVFORMAT_54
               U avformat_open_input@@LIBAVFORMAT_54
               U av_frame_alloc
               U av_image_alloc@@LIBAVUTIL_52
               U av_log@@LIBAVUTIL_52
               U av_register_all@@LIBAVFORMAT_54
  

  So, obviously, there is something wrong with av_frame_alloc. Why do I get a symbol lookup error every time I want to call av_frame_alloc?

  Thanks!

• What does "level" mean in FFprobe output ?

  8 mars 2017, par shintaroid

  I do not understand some attributes in the output by FFprobe

  For a sample file

  $ ffprobe -v error -show_format -show_streams input.mp4
  [STREAM]
  index=0
  codec_name=h264
  codec_long_name=H.264 / AVC / MPEG-4 AVC / MPEG-4 part 10
  profile=High
  width=320
  height=240
  has_b_frames=2
  pix_fmt=yuv420p
  level=13                <= This one!
  color_range=N/A
  

  What does "level" mean here? Is there any document explain those attributes?

• Does GeForce support GPU-accelerated video processing with FFmpeg ?

  8 mars 2017, par shintaroid

  On this page, it says "GeForce" is supported

  HW accelerated encode and decode are supported on NVIDIA GeForce, Quadro, Tesla, and GRID products with Fermi, Kepler, Maxwell and Pascal generation GPUs.

  But I cannot find GeForce in the listed matrix on the same page. So does GeForce support or not?

• Getting realtime output from ffmpeg to be used in progress bar (PyQt4, stdout)

  8 mars 2017, par Jason O'Neil

  I've looked at a number of questions but still can't quite figure this out. I'm using PyQt, and am hoping to run ffmpeg -i file.mp4 file.avi and get the output as it streams so I can create a progress bar.

  I've looked at these questions: Can ffmpeg show a progress bar? http://stackoverflow.com/questions/1606795/catching-stdout-in-realtime-from-subprocess

  I'm able to see the output of a rsync command, using this code:

  import subprocess, time, os, sys
  
  cmd = "rsync -vaz -P source/ dest/"
  p, line = True, 'start'
  
  
  p = subprocess.Popen(cmd,
                       shell=True,
                       bufsize=64,
                       stdin=subprocess.PIPE,
                       stderr=subprocess.PIPE,
                       stdout=subprocess.PIPE)
  
  for line in p.stdout:
      print("OUTPUT>>> " + str(line.rstrip()))
      p.stdout.flush()
  

  But when I change the command to ffmpeg -i file.mp4 file.avi I receive no output. I'm guessing this has something to do with stdout / output buffering, but I'm stuck as to how to read the line that looks like

  frame=   51 fps= 27 q=31.0 Lsize=     769kB time=2.04 bitrate=3092.8kbits/s
  

  Which I could use to figure out progress.

  Can someone show me an example of how to get this info from ffmpeg into python, with or without the use of PyQt (if possible)

  ---

  EDIT: I ended up going with jlp's solution, my code looked like this:

  #!/usr/bin/python
  import pexpect
  
  cmd = 'ffmpeg -i file.MTS file.avi'
  thread = pexpect.spawn(cmd)
  print "started %s" % cmd
  cpl = thread.compile_pattern_list([
      pexpect.EOF,
      "frame= *\d+",
      '(.+)'
  ])
  while True:
      i = thread.expect_list(cpl, timeout=None)
      if i == 0: # EOF
          print "the sub process exited"
          break
      elif i == 1:
          frame_number = thread.match.group(0)
          print frame_number
          thread.close
      elif i == 2:
          #unknown_line = thread.match.group(0)
          #print unknown_line
          pass
  

  Which gives this output:

  started ffmpeg -i file.MTS file.avi
  frame=   13
  frame=   31
  frame=   48
  frame=   64
  frame=   80
  frame=   97
  frame=  115
  frame=  133
  frame=  152
  frame=  170
  frame=  188
  frame=  205
  frame=  220
  frame=  226
  the sub process exited
  

  Perfect!