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• Audio drift issue. Creating video frames programmatically and syncing with midi/audio in java

  6 septembre 2017, par user6688986

  I want to create a video that changes to the notes on a midi file. I am recording the midi then outputting it as wav.

  In java I read the midi file, create images based on the notes played. I am calculating the time between notes and using this to determine the number of frames with this code :

      for(int i = 0; i < noteImages.size(); i++) {
  
          for(int j = 0; j < frameRate * (noteLengths.get(i) / 1000); j++) {
  
              videoFrames.add(noteImages.get(i));
  
              frameCount++;
  
          }
  
      }

  I then use ffmpeg to create the video from the images with audio using this command :

  ffmpeg -r 60 -f image2 -i pic%05d.png -itsoffset 3 -i audio.wav -c:v libx264 -c:a aac -pix_fmt yuv420p -crf 23 -r 24 -shortest -y output.mp4 

  The audio starts okay then gradually goes out of sync. If I use higher fps when creating the images it is less pronounced, but I need to use at least 300fps to get it close and it is still not quite right. Any ideas on how to correct this ?

• avformat/concatdec : add fallback for calculating file duration

  29 août 2017, par Justin Ruggles

  avformat/concatdec : add fallback for calculating file duration
  If a file does not have a known duration, this leads to the timestamps
  
  starting over for the next file, causing non-monotonic timestamps.
  
  To prevent this, track the duration during demuxing and use it to
  
  determine the current file duration before opening the next file.
  Signed-off-by : Derek Buitenhuis <derek.buitenhuis@gmail.com>
  

  • [DH] libavformat/concatdec.c

• Malloc Check Failed when opening video stream

  30 août 2017, par donturner

  I’m writing a BlackBerry 10 application which decodes an H264 video stream (from a Parrot AR Drone) using ffmpeg and libx264. These libraries have both been compiled for BlackBerry QNX.

  Here’s my code :

  av_register_all();
  
  avcodec_register_all();
  
  avformat_network_init();
  
  
  
  printf("AV setup complete\n");
  
  
  
  const char* drone_addr = "http://192.168.1.1:5555";
  
  AVFormatContext* pFormatCtx = NULL;
  
  AVInputFormat* pInputFormat = av_find_input_format("H264");
  
  
  
  printf("Opening video feed from drone\n");
  
  
  
  //THIS LINE FAILS 
  
  int result = avformat_open_input(&pFormatCtx, drone_addr, pInputFormat, NULL); 

  The last line fails with the error :

  Malloc Check Failed: :../../dlist.c:1168

  How can I fix this error or debug it further ?

  Update : The error only occurs when I supply pInputFormat to avformat_open_input. If I supply NULL I don’t get an error. But for my app I must supply this parameter since it is not possible for ffmpeg to determine the video format from the feed alone.