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• fftools/ffmpeg : add thread-aware transcode scheduling infrastructure

  18 mai 2023, par Anton Khirnov

  fftools/ffmpeg : add thread-aware transcode scheduling infrastructure
  See the comment block at the top of fftools/ffmpeg_sched.h for more
  
  details on what this scheduler is for.
  This commit adds the scheduling code itself, along with minimal
  
  integration with the rest of the program :
  
  * allocating and freeing the scheduler
  
  * passing it throughout the call stack in order to register the
  
    individual components (demuxers/decoders/filtergraphs/encoders/muxers)
  
    with the scheduler
  The scheduler is not actually used as of this commit, so it should not
  
  result in any change in behavior. That will change in future commits.
  

  • [DH] fftools/Makefile
  • [DH] fftools/ffmpeg.c
  • [DH] fftools/ffmpeg.h
  • [DH] fftools/ffmpeg_dec.c
  • [DH] fftools/ffmpeg_demux.c
  • [DH] fftools/ffmpeg_enc.c
  • [DH] fftools/ffmpeg_filter.c
  • [DH] fftools/ffmpeg_mux.c
  • [DH] fftools/ffmpeg_mux.h
  • [DH] fftools/ffmpeg_mux_init.c
  • [DH] fftools/ffmpeg_opt.c
  • [DH] fftools/ffmpeg_sched.c
  • [DH] fftools/ffmpeg_sched.h

• ValueError : I/O operation on closed file with ffmpeg

  22 mars 2018, par AstroCoda

  I’m trying to get this (minimal working example) code to compile in a virtual environment on Anaconda which I’ve set up in a supercomputing cluster :

  import numpy as np
  
  import matplotlib
  
  matplotlib.use("Agg")
  
  import matplotlib.pyplot as plt
  
  import matplotlib.animation as manimation
  
  
  
  FFMpegWriter = manimation.writers['ffmpeg']
  
  metadata = dict(title='Movie Test', artist='Matplotlib',
  
              comment='Movie support!')
  
  writer = FFMpegWriter(fps=15, metadata=metadata)
  
  
  
  fig = plt.figure()
  
  l, = plt.plot([], [], 'k-o')
  
  
  
  plt.xlim(-5, 5)
  
  plt.ylim(-5, 5)
  
  
  
  x0, y0 = 0, 0
  
  
  
  with writer.saving(fig, "writer_test.mp4", 100):
  
      for i in range(100):
  
          x0 += 0.1 * np.random.randn()
  
          y0 += 0.1 * np.random.randn()
  
          l.set_data(x0, y0)
  
          writer.grab_frame()

  The thing is, this code works absolutely fine on my local machine (MacOSX) - Anaconda distribution ; Python 2.7 ; same matplotlib and numpy version, and I have ffmpeg on Anaconda ; I have ffmpeg on the cluster as well, albeit at a different version to the one on Python (but no issue with this on my local machine). When I run the code on the cluster, I get :

  Traceback (most recent call last):
  
    File "movie_test.py", line 25, in <module>
  
      writer.grab_frame()
  
    File "~/anaconda2/envs/test_movie/lib/python2.7/contextlib.py", line 35, in __exit__
  
      self.gen.throw(type, value, traceback)
  
    File "~/anaconda2/envs/test_movie/lib/python2.7/site-packages/matplotlib/animation.py", line 241, in saving
  
      self.finish()
  
    File "~/anaconda2/envs/test_movie/lib/python2.7/site-packages/matplotlib/animation.py", line 367, in finish
  
      self.cleanup()
  
    File "~/anaconda2/envs/test_movie/lib/python2.7/site-packages/matplotlib/animation.py", line 405, in cleanup
  
      out, err = self._proc.communicate()
  
    File "~/anaconda2/envs/test_movie/lib/python2.7/site-packages/subprocess32.py", line 927, in communicate
  
      stdout, stderr = self._communicate(input, endtime, timeout)
  
    File "~/anaconda2/envs/test_movie/lib/python2.7/site-packages/subprocess32.py", line 1713, in _communicate
  
      orig_timeout)
  
    File "~/anaconda2/envs/test_movie/lib/python2.7/site-packages/subprocess32.py", line 1769, in _communicate_with_poll
  
      register_and_append(self.stdout, select_POLLIN_POLLPRI)
  
    File "~/anaconda2/envs/test_movie/lib/python2.7/site-packages/subprocess32.py", line 1748, in register_and_append
  
      poller.register(file_obj.fileno(), eventmask)
  
  ValueError: I/O operation on closed file
  
  </module>

  All the searches I’ve made correspond to relatively simple text write in/out operations, but not for videos. Thanks in advance for the help !

• Saving frames as images using FFmpeg

  25 octobre 2014, par Mr Almighty

  There are some tutorials on the internet about it, most of them is using deprecated functions and unfortunately the API use to broke and it makes a mess and I’m really confused.

  I’m following tutorials, learning with the documentation and seeing the examples of the current version (even that way some examples does not work).

  What I’m trying to do is to save frames in .png, following the examples and reading I did this, but I’m confused about the conversion the frame to RBG and saving it :

  #include <iostream>
  
  
  
  extern "C"
  
  {
  
      #include <libavcodec></libavcodec>avcodec.h>
  
      #include <libavformat></libavformat>avformat.h>
  
      #include <libavutil></libavutil>avutil.h>
  
  }
  
  
  
  int main(int argc, char ** argv)
  
  {
  
      if (argc &lt; 2)
  
      {
  
          av_log(0, AV_LOG_FATAL, "Usage: %s <input />", argv[0]);
  
          return -1;
  
      }
  
  
  
      const char * filename = argv[1];
  
  
  
      // register all codecs and formats
  
      av_register_all();
  
  
  
      // open input file, and allocate format context
  
      AVFormatContext *avFormatContext = avformat_alloc_context();
  
  
  
      if (avformat_open_input(&amp;avFormatContext, filename, 0, 0) &lt; 0)
  
      {
  
          av_log(0, AV_LOG_FATAL, "Could not open source file %s", filename);
  
          return -1;
  
      }
  
  
  
      // retrieve stream information
  
      if (avformat_find_stream_info(avFormatContext, 0) &lt; 0)
  
      {
  
          av_log(0, AV_LOG_FATAL, "Could not find stream information");
  
          return -1;
  
      }
  
  
  
      // dump information about file onto standard error
  
      av_dump_format(avFormatContext, 0, filename, 0);
  
  
  
      // find the "best" video stream in the file.
  
      int result = av_find_best_stream(avFormatContext, AVMEDIA_TYPE_VIDEO, -1, -1, 0, 0);
  
  
  
      if (result &lt; 0)
  
      {
  
          av_log(0, AV_LOG_FATAL, "Could not find %s stream in input file '%s'", av_get_media_type_string(AVMEDIA_TYPE_VIDEO), filename);
  
          return -1;
  
      }
  
  
  
      int stream = result;
  
      AVStream *avStream = avFormatContext->streams[stream];
  
      AVCodecContext *avCodecContext = avStream->codec;
  
  
  
      // find decoder for the stream
  
      AVCodec *avCodec = avcodec_find_decoder(avCodecContext->codec_id);
  
  
  
      if (! avCodec)
  
      {
  
          av_log(0, AV_LOG_FATAL, "Failed to find %s codec", av_get_media_type_string(AVMEDIA_TYPE_VIDEO));
  
          return -1;
  
      }
  
  
  
      // init the decoders, with reference counting
  
      AVDictionary *avDictionary = 0;
  
      av_dict_set(&amp;avDictionary, "refcounted_frames", "1", 0);
  
  
  
      if (result = avcodec_open2(avCodecContext, avCodec, &amp;avDictionary) &lt; 0)
  
      {
  
          av_log(0, AV_LOG_FATAL, "Failed to open %s codec", av_get_media_type_string(AVMEDIA_TYPE_VIDEO));
  
          return -1;
  
      }
  
  
  
      AVFrame *avFrame = av_frame_alloc();
  
  
  
      if (! avFrame)
  
      {
  
          av_log(0, AV_LOG_FATAL, "Could not allocate frame");
  
          return -1;
  
      }
  
  
  
      // initialize packet, set data to null, let the demuxer fill it
  
      AVPacket avPacket;
  
      av_init_packet(&amp;avPacket);
  
      avPacket.data = 0;
  
      avPacket.size = 0;
  
  
  
      while (av_read_frame(avFormatContext, &amp;avPacket) >= 0)
  
      {
  
          if (avPacket.stream_index == stream)
  
          {
  
              int success = avcodec_decode_video2(avCodecContext, avFrame, &amp;success, &amp;avPacket);
  
  
  
              if (success &lt;= 0)
  
              {
  
                  av_log(0, AV_LOG_FATAL, "Error decoding video frame");
  
                  return -1;
  
              }
  
  
  
              // ... saving...
  
          }
  
      }
  
  
  
      avcodec_close(avCodecContext);
  
      avformat_close_input(&amp;avFormatContext);
  
      av_frame_free(&amp;avFrame);
  
  
  
      return 0;
  
  }
  
  </iostream>