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• Error in av_write_frame when streaming over network (libavformat of ffmpeg)

  4 décembre 2014, par user4324788

  I have been using the ffmpeg libraries (libavcodec, libavformat, etc.) in my C# application to encode buffer data retrieved from my camera/microphone (using DirectShow.Net) and stream it over the network to a destination IP address using MPEG-TS and UDP.

  I communicate with the C++ libraries of ffmpeg through a C# wrapper (.dll) which I call with DllImport. I send the raw video and audio buffer data from C# to the C++ libraries for the purpose of encoding, muxing, and streaming.

  The encoding and streaming works perfectly, however I sometimes seem to encounter a problem with the “av_write_frame” function which is used to write the encoded packet to the output media. After a seemingly random period of time, the following line produces an error ("oc" being the AVFormatContext and "pkt" being the AVPacket) :

  av_write_frame(oc, &pkt)

  One of two errors occurs :

  • An I/O error is returned (return value -5).
  • A ’System.AccessViolationException’ (Attempted to read or write protected memory. This is often an indication that other memory is corrupt.) is thrown.

  This error sometimes occurs after a few minutes of streaming, other times after a much longer period (up to 20 minutes). Also, this error occurs at both video and audio encoding/writing, so I haven’t been able to pinpoint the exact reason behind this problem. Unfortunately it always results in my application either crashing or the streaming to stop working.

  I have tried catching the AccessViolationException, which sometimes allows the application to continue for a little longer, but eventually it ends up exiting without any warning.
  In case of the I/O error, I can reset my application, but eventually it still crashes.

  Any help with fixing this issue would be greatly appreciated !

  Thank you very much in advance.

• How to terminate an infinite process with an specific time duration

  3 janvier 2014, par poc

  I tried to run hundreds of commands in a batch.

  So I have to let each command can be terminated under an duration, and then executes the next.

  However, the command will be terminated, because the timeout option argument is not working for ffmpeg

  So I wonder is there any workaround that can terminate an command within an time duration.

  I can terminate the command (which is running in foreground) by type 'q'

  def get_video_clip(self, rtsp_link="rtsp://localhost:554", f_name="sample", period=5):
  
          cmd = "ffmpeg -i {0} -acodec copy -vcodec copy {1}.mp4 -t {2}".format(  rtsp_link,
  
                                                                                  f_name,
  
                                                                                  period
  
                                                                                  )
  
          ap(cmd)
  
  
  
          os.popen(cmd)
  
          pass

  I attempted to capture streaming via rtsp and limit the clip duration under 3 sec

  But the option doesn't work. The ffmpeg won't be terminated anymore.

  Is there any workaround to fix the problem.

  Because I have to run hundreds of similar commands in a batch with Python script.

  ffmpeg -loglevel verbose   -i rtsp://172.19.1.42/live.sdp -acodec copy -vcodec copy  c0_s1_h264_640x480_30_vbr_500_99_40000000.mp4 -timeout 3 -y

  $ ffmpeg -h ffmpeg version 1.2.4 Copyright (c) 2000-2013 the FFmpeg
  developers built on Nov 22 2013 11:59:59 with Apple LLVM version 5.0
  (clang-500.2.79) (based on LLVM 3.3svn)

  The detailed log at https://gist.github.com/poc7667/8234701

• Nginx with rtmp-module stalls between streams

  14 janvier 2015, par churchmf

  I’m experiencing some troubles using NGINX with rtmp-module as a media server. I wish to present a continuous video as a live stream (with up to 60 second latency). However, due to some hardware constraints, I am unable to stream directly from the device. Instead, I can save out X amount of seconds from the device’s buffer as an MP4. My solution has been to save X seconds of video from the device then stream that X seconds, rise and repeat. This has been working mostly well, except for stalls ( 20 seconds) in the stream between calls.

  I have searched far and wide for a solution to this however most of the people experiencing this problem have the collection of videos before starting the stream and can simply concatenate them.

  My running theory is that when a stream finishes, it does an unpublish event in NGINX followed by a timeout period. This prevents the NGINX server from receiving the next publish until the timeout period has expired. I have tried adjusting nginx.config values related to timeouts, respawns, restarts, and publish, but to no avail.

  Pseudocode :
  while true
   > capture X seconds of video to "output.mp4" (this takes less than 300ms)
   > stream the MP4 with FFMPEG (takes X seconds using -re)

  FFMPEG call :
  ffmpeg -re -i "output.mp4" -vcodec libx264 -preset veryfast -maxrate 2000k -bufsize 4000k -g 60 -acodec libmp3lame -b:a 128k -ac 2 -ar 44100 -f flv rtmp :/MYSERVER/live/output

  I am using JWPlayer client side to watch the video stream, however I experience similar issues using VLC.

  I have been trying to figure this out for a few days and I would appreciate any insight an expert to video streaming and NGINX can give. Thank you !