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• ffmpeg to dvb-c. Need some advices

  12 octobre 2017, par pentarhh

  I’d like to get some advices about ffmpeg transcoding and broadcasting it to DVB-C environment.
  Have a server, based on Linux with external GPUs based on Nvidia P4000. Target of this machine is getting live streams at HLS, then it transcode files to multicast UDP. After transcoding multicast TS gets to receiver (Sumavision EMR 3.0), then modulates into DVB-C with QAM-card for next transmission to fiber.

  So, there is a strange trouble. In IPTV such stream have no visible troubles. Analyzing TS, saw an errors with PCR accuracy (>500 ms ’cause of pseudo-CBR) and very rare discontinuity errors, that could be based on source errors.
  Then I take it to Sumavision and apply inbound parameters (just remultiplexing this stream with making loyal reference, buffer size values and CBR output values). Analyzer sees no problem, after putting in QAM-modulator customize output streams, such as PSI/SI tables, frequency, symbol rate etc.

  After I see the result at some test TVs. First one shows this channel great, with no visible troubles (no artefacts, no asynchronous sound). Second TV has a problem of video, it looks like a lost frames. Sometimes sound interrupts for a milliseconds. But there is no freezes
  ’Cause of ETR 101 290 passes well, may be this model of TV decodes this service incorrect. Example of video record is here.

  Here is the code of ffmpeg. May be, I missed some common parameters, that may get the output is better for such tuners. Can you see it’s alright ?

  sudo -u nobody ffmpeg -threads 0 -v warning -re -hwaccel cuvid -hwaccel_device 2 -c:v h264_cuvid -deint 0 -i http://x.x.x.x/playlist.m3u8 -bsf:v h264_mp4toannexb -map 0:0 -map 0:1 -vcodec h264_nvenc -gpu 2 -cbr true -sc_threshold 0 -filter:v scale_npp=960:540:interp_algo=lanczos -vprofile baseline -b:v 1000k -bufsize 1400k -maxrate 1400k -minrate 900k -force_key_frames 1 -g 50 -bf 0 -refs 1 -r 25 -strict experimental -c:a aac -b:a 64K -af aresample=44100 -ac 2 -flags -global_header -f segment -segment_format mpegts -segment_time 10 /path1/segment-1507744758-%06d.ts -map 0:0 -map 0:1 -vcodec h264_nvenc -gpu 2 -cbr true -sc_threshold 0 -vprofile high -b:v 8000k -bufsize 400k -maxrate 9000k -minrate 7200k -force_key_frames 1 -g 50 -bf 2 -refs 1 -r 25 -strict experimental -c:a aac -b:a 192K -af aresample=44100 -ac 2 -flags -global_header -f tee 
  
  [f=segment:segment_format=mpegts:segment_time=10]/path2/segment-1507744758-%06d.ts|[f=mpegts:muxrate=9333k:mpegts_pmt_start_pid=0xB4A:mpegts_start_pid=0xB4B]'udp://y.y.y.y:1234?buffer_size=0&overrun_nonfatal_option=1&pkt_size=1316&ttl=15'

• Live streaming doesn't work

  18 octobre 2017, par John Smith

  I’m using FFmpeg to capture my screen :

  ffmpeg -f dshow -i video="UScreenCapture" -r 5 -s 640x480 -acodec libmp3lame -ac 1 -vcodec mpeg 4 -vtag divx -q 10 -f mpegts tcp://127.0.0.1:1234

  so let it stream to somewhere. The accepter script :

   error_reporting(E_ALL); /* Allow the script to hang around waiting for connections. */
  
   set_time_limit(30); /* Turn on implicit output flushing so we see what we're getting as it comes in. */
  
   ob_implicit_flush();
  
  
  
  
  
  $address = '127.0.0.1';
  
  $port = 1234;
  
  $outfile = dirname(__FILE__)."/output.flv";
  
  $ofp = fopen($outfile, 'wb');
  
  
  
   if (($sock = socket_create(AF_INET, SOCK_STREAM, SOL_TCP)) === false) { echo "socket_create() failed: reason: " . socket_strerror(socket_last_error()) . "\n"; sleep (5); die; }
  
   if (socket_bind($sock, $address, $port) === false) { echo "socket_bind() failed: reason: " . socket_strerror(socket_last_error($sock)) . "\n"; sleep (5); die; }
  
   if (socket_listen($sock, 5) === false) { echo "socket_listen() failed: reason: " . socket_strerror(socket_last_error($sock)) . "\n"; sleep (5); die; }
  
   if (($msgsock = socket_accept($sock)) === false) { echo "socket_accept() failed: reason: " . socket_strerror(socket_last_error($sock)) . "\n"; sleep (5); break; }
  
   do {
  
      $a = '';
  
      socket_recv ($msgsock, $a, 65536, MSG_WAITALL);
  
      fwrite ($ofp, $a);
  
      //echo strlen($a)."\r\n";
  
   } while (true);

  it seems to save the stuff to the disk OK. Now here comes the html :

  I dont really know how to do this, but based on an example :

  <video src="/output.flv"></video>

  but it doesn’t do anything. And if I want to stream the live incoming stuff, then what’s the matter ?

• How to receive MPEGT-TS stream with Pro-MPEG FEC using ffmpeg ?

  1er février 2019, par Antoxic

  I have two Linux computers connected through internet transmitting MPEG-TS from one PC to the other. The connection is not perfect and sometimes the packets get lost. I want to transmit an MPEG-TS from one PC to another using PRO-MPEG in order to enable error correction (FEC). On one computer I’m running ffmpeg with :

  ffmpeg-i "http://1.2.3.4:1234 -map 0 -r 25 -c:v copy -f rtp_mpegts -fec prompeg=l=5:d=5 rtp://4.3.2.1:4321

  And now I need to receive that stream and I want to correct the transmission errors using the FEC info which comes on RTP port +1 and +2. How can I achieve that with ffmpeg ? If it is not possible wit ffmpeg, what other solution can I use ?

  I’m using an ffmpeg snapshot version N-87867-g0655810. I can’t find any information about how to receive it and use the FEC information to recover transmission errors.