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• Saving H264 RTP Packets In Useful Form

  14 novembre 2014, par Nick Lima

  I know that it is possible to save RTP h264 streams using Wireshark and VLC. But in order to learn more about video streaming I am trying to do it myself. There are several related questions that make for good reading on this topic :

  How to process raw UDP packets so that they can be decoded by a decoder filter in a directshow source filter

  Problem to Decode H264 video over RTP with ffmpeg (libavcodec)

  How to convert H.264 UDP packets to playable media stream or file (defragmentation)

  With those as background, this is where I am currently :

  • I can receive RTP packets over UTP.
  • I parse packets as discussed in the questions above.
  • I write the packets to a file, separated by \x000001 and add the NAL byte again according to the above guides.
  • At the beginning of the file I put the SPS and PPS which I got from my code’s RTSP conversation with the server (again seperated by the correct bytes).

  I end up with a file of supposedly a lot of NAL frames. I then try to run ffmpeg on the .264 file to create a .mp4. This brings up several errors :

  [h264 @ 0x15257a0] decode_slice_header error

  [h264 @ 0x15257a0] no frame !

  [h264 @ 0x15257a0] non-existing PPS referenced

  [h264 @ 0x15257a0] non-existing PPS 0 referenced

  [buffer @ 0x15e16a0] Invalid pixel format string ’-1’

  I am essentially at a standstill until I can figure out this problem. I have thouroughly read the questions I linked to above, and the stream is definitely viewable because I can connect and watch it via VLC and the incoming packets are definitely H264 RTP packets according to wireshark. If VLC can do it why can’t I ! I would greatly appreciate any insight into my errors and possible a summary of the three linked questions that resolves the disagreements between them.

• Pushing data while downloading to ffmpeg

  5 avril 2019, par Nguyễn Thành Đạt

  I have try to relivestream video to facebook with source from youtube.

  I use the ytdl to download video from youtube.
  I want to during the video download process, i will livestream

  When i run my source in blow by nodejs then the error appears :

  var url = 'https://www.youtube.com/watch?v=CTL_5dqDOyc';
  
  var ffmpeg = spawn('ffmpeg', ['-re', '-i', 'pipe:0', '-i', 'logo.png',' acodec', 'libmp3lame',  '-ar', '44100', '-b:a', '128k', '-profile:v', 'baseline', '-s', '854x480', '-bufsize', '6000k', '-vcodec', 'libx264', '-preset', 'veryfast', '-g', '30', '-r', '30', '-f', 'flv', 'rpmt link']);
  
  ytdl(url).pipe(ffmpeg.stdin);

• How do I know if ffmpeg is using a hardware decoder ?

  27 janvier 2021, par farza

  I noticed when I read a video frame by frame via ffmpeg, my CPU usage explodes to 120%.

  



  ffmpeg -i video.webm thumb%04d.jpg -hide_banner


  



  But, if i simply watch a video locally it barely eats up any CPU.

  



  I'm guessing the issue here is that ffmpeg isn't using my hardware decoder (on OS X no GPU). How would I even check ?

  



  Any other issue that could be occurring ?