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• Ffmpeg alpha from udp input

  30 mai 2017, par Bob Ross

  I’m trying to stream a video that is composed from a base video and an overlay video with an alpha channel.

  I receive both of the incoming input streams as udp inputs so I can change them at runtime.

  The problem is that when I use avi as the format for the overlay stream i get this error :

  udp ://127.0.0.1 :$port2 : Invalid data found when processing input

  and when I use mpegts as the format for the overlay stream I get this error :

  Stream specifier ’:v’ in filtergraph description [0:v][1:v]overlay=format=rgb matches no streams

  The main ffmpeg command :

  ffmpeg -re -i udp://127.0.0.1:${port1} -vcodec qtrle -i udp://127.0.0.1:${port2} -s 854x480 -filter_complex [0:v][1:v]overlay=format=rgb -c:v libx264 -preset ultrafast -f flv ${output}

  The base stream :

  ffmpeg -re -i ${hls_source} -c:v libx264 -vf scale=854:480 -f mpegts udp://127.0.0.1:${port1}

  The overlay stream with alpha channel :

  ffmpeg -re -i z.mov -vcodec qtrle -f avi udp://127.0.0.1:${port2}

  It’s worth noting that when I switch one of the udp inputs with a recorded file, It does work.

• Interplay MVE : Implement MVE SEND_BUFFER operation

  25 juin 2017, par Hein-Pieter van Braam

  Interplay MVE : Implement MVE SEND_BUFFER operation
  Interplay MVE movies have a SEND_BUFFER operation. Only after this
  
  command does the current decoding buffer get displayed. This is required
  
  for the other frame formats. They are fixed-size and can't always encode
  
  a full frame worth of pixeldata.
  This code prevents half-finished frames from being emitted.
  Signed-off-by : Hein-Pieter van Braam <hp@tmm.cx>
  

  • [DH] libavcodec/interplayvideo.c
  • [DH] libavformat/ipmovie.c

• DTS value repeating, not synced with PTS (ffmpeg)

  24 novembre 2017, par Damian

  Just a quick question in regards to video encoding/muxing a video file with ffmpeg. Basically, I have my muxer functioning and I’m trying to have my packets output the correct PTS/DTS.

  This is a portion of my code that encodes my AVFrame, muxing it to an output file :

  int ret;
  
  int got_packet = 0;
  
  
  
  AVPacket pkt = { 0 };
  
  av_init_packet(&pkt);
  
  
  
  pkt.data = NULL;
  
  pkt.size = 0;
  
  
  
  /* encode the image */
  
  ret = avcodec_encode_video2(cc, &pkt, frame, &got_packet);
  
  if (ret < 0)
  
  {
  
      fprintf(stderr, "rasterbench: error encoding video frame: %s\n", av_err2str(ret));
  
      exit(EXIT_FAILURE);
  
  }
  
  
  
  if (got_packet)
  
  {
  
      av_packet_rescale_ts(&pkt, cc->time_base, st->time_base);
  
  
  
      fprintf(stderr, "\npkt.pts     = %ld\n", pkt.pts);
  
      fprintf(stderr,   "pkt.dts     = %ld\n", pkt.dts);
  
      fprintf(stderr, "rasterbench: writing frame\n");
  
  
  
      ret = av_interleaved_write_frame(fmt_ctx, &pkt);
  
      av_packet_unref(&pkt);
  
  }
  
  else
  
  {
  
      ret = 0;
  
  }
  
  
  
  ...

  I’m then getting an output of the following :

  pkt.pts     = 0
  
  pkt.dts     = 0
  
  rasterbench: writing frame
  
  
  
  pkt.pts     = 1502
  
  pkt.dts     = 0
  
  rasterbench: writing frame
  
  
  
  pkt.pts     = 3003
  
  pkt.dts     = 1502
  
  rasterbench: writing frame
  
  
  
  pkt.pts     = 4505
  
  pkt.dts     = 3003
  
  rasterbench: writing frame
  
  
  
  ...

  My goal is to have my PST and DST both with the pattern : 1502, 3003, 4505, 6006, 7508, ...

  But it seems that the first DTS value is repeating once, and thus being off-sync with it’s corresponding PTS value. It’s also worth mentioning that the codec context was configured to have no b-frames, so only i- and p- frames are present here.

  Does anyone with more experience have some insight on this ?