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• How to efficiently clear ffmpeg buffer

  23 juillet 2020, par KmanOfficial

  I am using Chiaki (https://github.com/thestr4ng3r/chiaki/) - A Open Source Video Streaming Application for the PS4.

  


  I have one issue though. The stream successfully shows the playstation but after about 60 seconds. The stream freezes and gets stuck on the last processed frame until I restart the application. I believe the issue is in the C++ file - (https://github.com/thestr4ng3r/chiaki/blob/master/gui/src/videodecoder.cpp) and the issue is specifically here : `

  


  void VideoDecoder::PushFrame(uint8_t *buf, size_t buf_size)
{
    {
        QMutexLocker locker(&mutex);

    AVPacket packet;
    av_init_packet(&packet);
    packet.data = buf;
    packet.size = buf_size;
    int r;
send_packet:
        r = avcodec_send_packet(codec_context, &packet);
        if(r != 0)
        {
            if(r == AVERROR(EAGAIN))
            {
                CHIAKI_LOGE(log, "AVCodec internal buffer is full removing frames before pushing");
                AVFrame *frame = av_frame_alloc();
                if(!frame)
                {
                    CHIAKI_LOGE(log, "Failed to alloc AVFrame");
                    return;
                }
                r = avcodec_receive_frame(codec_context, frame);
                av_frame_free(&frame);
                if(r != 0)
                {
                    CHIAKI_LOGE(log, "Failed to pull frame");
                    return;
                }
                goto send_packet;
            }
            else
            {
                char errbuf[128];
                av_make_error_string(errbuf, sizeof(errbuf), r);
                CHIAKI_LOGE(log, "Failed to push frame: %s", errbuf);
                return;
            }
        }
    }

    emit FramesAvailable();
}


  


  `

  


  I believe so as the application log constantly prints this logged message : "AVCodec internal buffer is full removing frames before pushing"

  


  I've tried looking at the ffmpeg manual and I am struggling on how to flush the internal buffer to get the stream constantly flowing can anyone point me in the correct direction. Thank you.

  


• Killing python ffmpeg subprocess breaks cli output

  27 septembre 2017, par JayLev

  I’m trying to execute a system command with subprocess and reading the output.

  But if the command takes more than 10 seconds I want to kill the subprocess.

  I’ve tried doing this in several ways.

  My last try was inspired by this post : https://stackoverflow.com/a/3326559/969208

  Example :

  import os
  
  import signal
  
  from subprocess import Popen, PIPE
  
  
  
  class Alarm(Exception):
  
      pass
  
  
  
  def alarm_handler(signum, frame):
  
      raise Alarm
  
  
  
  def pexec(args):
  
  
  
      p = Popen(args, stdout=PIPE, stderr=PIPE)
  
  
  
      signal.signal(signal.SIGALRM, alarm_handler)
  
      signal.alarm(10)
  
  
  
      stdout = stderr = ''
  
      try:
  
          stdout, stderr = p.communicate()
  
          signal.alarm(0)
  
      except Alarm:
  
          try:
  
              os.kill(p.pid, signal.SIGKILL)
  
          except:
  
              pass
  
  
  
      return (stdout, stderr)

  The problem is : After the program exits no chars are shown in the cli until I hit return. And hitting return will not give me a new line.

  I suppose this has something to do with the stdout and stderr pipe.

  I’ve tried flushing and reading from the pipe (p.stdout.flush())

  I’ve also tried with different Popen args, but might’ve missed something. Just thought I’d keep it simple here.

  I’m running this on a Debian server.

  Am I missing something here ?

  EDIT :

  It seems this is only the case when killing an ongoing ffmpeg process. If the ffmpeg process exits normally before 10 seconds, there is no problem at all.

  I’ve tried executing a couple of different command that take longer than 10 seconds, one who prints output, one who doesn’t and a ffmpeg command to check the integrity of a file.

  args = ['sleep', '12s'] # Works fine
  
  args = ['ls', '-R', '/var'] # Works fine, prints lots for a long time
  
  args = ['ffmpeg', '-v', '1', '-i', 'large_file.mov','-f', 'null', '-'] # Breaks cli output

  I believe ffmpeg prints using \r and prints everything on the strerr pipe. Can this be the cause ? Any ideas how to fix it ?

• Killing python ffmpeg subprocess breaks cli output

  17 mars 2016, par JayLev

  I’m trying to execute a system command with subprocess and reading the output.

  But if the command takes more than 10 seconds I want to kill the subprocess.

  I’ve tried doing this in several ways.

  My last try was inspired by this post : http://stackoverflow.com/a/3326559/969208

  Example :

  import os
  
  import signal
  
  from subprocess import Popen, PIPE
  
  
  
  class Alarm(Exception):
  
      pass
  
  
  
  def alarm_handler(signum, frame):
  
      raise Alarm
  
  
  
  def pexec(args):
  
  
  
      p = Popen(args, stdout=PIPE, stderr=PIPE)
  
  
  
      signal.signal(signal.SIGALRM, alarm_handler)
  
      signal.alarm(10)
  
  
  
      stdout = stderr = ''
  
      try:
  
          stdout, stderr = p.communicate()
  
          signal.alarm(0)
  
      except Alarm:
  
          try:
  
              os.kill(p.pid, signal.SIGKILL)
  
          except:
  
              pass
  
  
  
      return (stdout, stderr)

  The problem is : After the program exits no chars are shown in the cli until I hit return. And hitting return will not give me a new line.

  I suppose this has something to do with the stdout and stderr pipe.

  I’ve tried flushing and reading from the pipe (p.stdout.flush())

  I’ve also tried with different Popen args, but might’ve missed something. Just thought I’d keep it simple here.

  I’m running this on a Debian server.

  Am I missing something here ?

  EDIT :

  It seems this is only the case when killing an ongoing ffmpeg process. If the ffmpeg process exits normally before 10 seconds, there is no problem at all.

  I’ve tried executing a couple of different command that take longer than 10 seconds, one who prints output, one who doesn’t and a ffmpeg command to check the integrity of a file.

  args = ['sleep', '12s'] # Works fine
  
  args = ['ls', '-R', '/var'] # Works fine, prints lots for a long time
  
  args = ['ffmpeg', '-v', '1', '-i', 'large_file.mov','-f', 'null', '-'] # Breaks cli output

  I believe ffmpeg prints using \r and prints everything on the strerr pipe. Can this be the cause ? Any ideas how to fix it ?