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• Is it possible to stream video over RTP without transcoding or compressing input file before transmitting using FFMpeg commandline ?

  11 avril 2017, par Souvik Das

  FFmpeg supports 2 type of RTP payload type : MPEGTS/MP2T (PT 33) & Dynamic (PT 96). Dynamic PT requires explicit SDP presence at receiver while MPEGTS/MP2T doesn’t.
  I used FFmpeg as both transmitter and receiver (with Loopback/localhost) and compared PSNR of the respective streams :

  Case 1 : FFmpeg Dynamic RTP

  Sender:
  
  
  
      ffmpeg -re -i 'sample.avi' -c:a copy -c:v copy -f rtp -y 'rtp://@225.0.0.1:5555' > sample.sdp
  
  
  
  Receiver:
  
  
  
      ffmpeg -protocol_whitelist file,udp,rtcp,rtp -i sample.sdp -y rec.ts
  
  
  
  Result:
  
  
  
      PSNR avg. = 38
  
  
  
  This means that in idle condition, we are still not getting a perfect stream. I suspect, it's because Transcoding still takes place which downgrades the quality of video before transmitting at sender.

  Case 2 : FFmpeg MPEGTS RTP

  Sender:
  
  
  
      ffmpeg -re -i 'sample.avi' -c:a copy -c:v copy -f rtp_mpegts -y 'rtp://@225.0.0.1:5555'
  
  
  
  Receiver:
  
  
  
  
  
      ffmpeg -protocol_whitelist file,udp,rtcp,rtp -i sample.sdp -f mpegts -y rec.ts
  
  
  
  Result:
  
  
  
      Large # Frame Losses!
  
  
  
  So, at Receiver, I used VLC for recording the streams. Although there was no/negligible frame loss, but PSNR avg. = 18 !!

  Earlier in a dedicated VLC Streamer & Recorder test, when the same video was streamed, PSNR avg. = Infinity (No Quality Loss). I want to shift to FFMpeg alternative for streaming because, I want to introduce some programmability factors for a sophisticated research work.

  Hence, It would be really great, if somebody could provide me some input as to how I can achieve uncompressed & lossless video streaming using FFMpeg over RTP.

  Notes :

  1. I must use RTP only. I can't use RTSP or other streaming methods incl. direct UDP (udp://)
  
  2. VLC Media Player / Libvlc used in this case, also used RTP for all cases.
  
  3. It can assumed that Streamer and Recorder are present on same disk or has same access to storage.
  
  4. Must support multicast!

• FFMPEG live recording is too fast

  22 avril 2017, par Anton Putau

  I am trying to record 55 seconds of radiostation.

  ffmpeg -t 55 -i http://19233.live.streamtheworld.com/BLZE_1.mp3 toofastrecord.mp3 .

  FFMPEG do this nearly for 10 seconds. How does it possible to have speed speed=5.67x instead 1 for live recording ?

  Below is FFMPEG output.

  ffmpeg -t 55 -i http://19233.live.streamtheworld.com/BLZE_1.mp3 toofastrecord.mp3
  
  ffmpeg version N-77715-gfc703f5 Copyright (c) 2000-2016 the FFmpeg developers
  
    built with gcc 5.2.0 (GCC)
  
    configuration: --enable-gpl --enable-version3 --disable-w32threads --enable-avisynth --enable-bzlib --enable-fontconfig --enable-frei0r --enable-gnutls --enable-iconv --enable-libass --enable-libbluray --enable-libbs2b --enable-libcaca --enable-libdcadec --enable-libfreetype --enable-libgme --enable-libgsm --enable-libilbc --enable-libmodplug --enable-libmp3lame --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-libopenjpeg --enable-libopus --enable-librtmp --enable-libschroedinger --enable-libsoxr --enable-libspeex --enable-libtheora --enable-libtwolame --enable-libvidstab --enable-libvo-aacenc --enable-libvo-amrwbenc --enable-libvorbis --enable-libvpx --enable-libwavpack --enable-libwebp --enable-libx264 --enable-libx265 --enable-libxavs --enable-libxvid --enable-libzimg --enable-lzma --enable-decklink --enable-zlib
  
    libavutil      55. 12.100 / 55. 12.100
  
    libavcodec     57. 21.100 / 57. 21.100
  
    libavformat    57. 21.101 / 57. 21.101
  
    libavdevice    57.  0.100 / 57.  0.100
  
    libavfilter     6. 23.100 /  6. 23.100
  
    libswscale      4.  0.100 /  4.  0.100
  
    libswresample   2.  0.101 /  2.  0.101
  
    libpostproc    54.  0.100 / 54.  0.100
  
  [mp3 @ 0000017b0ad9aa00] Skipping 0 bytes of junk at 0.
  
  Input #0, mp3, from 'http://19233.live.streamtheworld.com/BLZE_1.mp3':
  
    Metadata:
  
      icy-br          : 64
  
      icy-description :
  
      icy-genre       : Talk
  
      icy-name        :
  
      icy-url         :
  
    Duration: N/A, start: 0.000000, bitrate: 64 kb/s
  
      Stream #0:0: Audio: mp3, 44100 Hz, mono, s16p, 64 kb/s
  
  Output #0, mp3, to 'toofastrecord.mp3':
  
    Metadata:
  
      icy-br          : 64
  
      icy-description :
  
      icy-genre       : Talk
  
      icy-name        :
  
      icy-url         :
  
      TSSE            : Lavf57.21.101
  
      Stream #0:0: Audio: mp3 (libmp3lame), 44100 Hz, mono, s16p
  
      Metadata:
  
        encoder         : Lavc57.21.100 libmp3lame
  
  Stream mapping:
  
    Stream #0:0 -> #0:0 (mp3 (native) -> mp3 (libmp3lame))
  
  Press [q] to stop, [?] for help
  
  size=     430kB time=00:00:55.01 bitrate=  64.1kbits/s speed=5.67x
  
  video:0kB audio:430kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: 0.077898%

• Stream desktop ffmpeg

  24 avril 2017, par Luzwitz

  I would like to stream the screen of my computer and send the stream to a server so that an external application recovers this stream.
  After doing some research, I think the best solution is FFmpeg (what do you think) ?

  So I tried to stream my screen and send the stream to a web server.
  So here is my small web server in C :

  int main(void) {
  
  int sock, clientlen, n, port = 12546;
  
  char buf[1024], *host;
  
  
  
  struct sockaddr_in serveraddr;
  
  struct sockaddr_in clientaddr;
  
  struct hostent *hostp;
  
  
  
  sock = socket(AF_INET, SOCK_DGRAM, 0);
  
  
  
  bzero((char *) &serveraddr, sizeof(serveraddr));
  
  
  
  serveraddr.sin_family = AF_INET;
  
  serveraddr.sin_addr.s_addr = htonl(INADDR_ANY);
  
  serveraddr.sin_port = htons((unsigned short)port);
  
  
  
  if(bind(sock, (struct sockaddr *) &serveraddr, sizeof(serveraddr)) < 0) 
  
      clientlen = sizeof(clientaddr);
  
  
  
  while (1)
  
  {
  
      bzero(buf, 1024);
  
  
  
      n = recvfrom(sock, buf, 1024, 0, (struct sockaddr *) &clientaddr, &clientlen);
  
  
  
      hostp = gethostbyaddr((const char *)&clientaddr.sin_addr.s_addr, sizeof(clientaddr.sin_addr.s_addr), AF_INET);
  
  
  
      host = inet_ntoa(clientaddr.sin_addr);
  
  
  
      printf("server received datagram from %s (%s)\n", hostp->h_name, host);
  
  
  
      printf("server received %d/%d bytes: %s\n", strlen(buf), n, buf);
  
  }
  
  
  
  return 0;
  
  }

  And here is the command I use to stream my screen :

  ffmpeg -video_size 1024x768 -framerate 25 -f x11grab -i :0.0+0,0 -vcodec libx264 -tune zerolatency -b:v 900k -f mpegts udp://192.168.1.12:12546

  And on my server, I want get this stream and create a dynamic mp4 file. It’s possible ? And how ?

  Thanks