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• How to use FFMPEG to determine actual FPS of an RTMP stream

  18 mai 2016, par Dexter1759

  I’m trying to determine the best way to analyse any RTMP stream. I’m currently settled upon the FFMPEG suite of tools, however, I find myself in need of help before I drive myself crazy.

  I’m trying to validate a stream, I’ve been asked to determine the following :

  • Can I connect to the stream ? - this can be done easily with FFProbe
  • Is there video ? (i.e. it’s not all black) - I’ve managed to build a POC so don’t think this will be a problem.
  • Is there audio ? (i.e. not all silent) - Again, don’t think this is a problem based on my POC.
  • Actual FPS - here’s where I get stuck because the meta data shows 25fps and that’s what FFTools return.

  However, using FFPlay I can see the odd message of "no frame !" and would prefer to calculate the actual FPS for comparison.

  Any help/advice with this toolset would be useful.

  (Note : I’ve also had other issues/questions with this toolset but have started with this one rather than dump a list here)

  Many thanks.

  EDIT - Forgot to mention the stream is of a live feed so things like "duration" and "nb_frames" return "N/A"

• How to use FFTools to determine actual FPS of an RTMP stream

  17 mai 2016, par Dexter1759

  I’m trying to determine the best way to analyse any RTMP stream. I’m currently settled upon the FFMPEG suite of tools, however, I find myself in need of help before I drive myself crazy.

  I’m trying to validate a stream, I’ve been asked to determine the following :

  • Can I connect to the stream ? - this can be done easily with FFProbe
  • Is there video ? (i.e. it’s not all black) - I’ve managed to build a POC so don’t think this will be a problem.
  • Is there audio ? (i.e. not all silent) - Again, don’t think this is a problem based on my POC.
  • Actual FPS - here’s where I get stuck because the meta data shows 25fps and that’s what FFTools return.

  However, using FFPlay I can see the odd message of "no frame !" and would prefer to calculate the actual FPS for comparison.

  Any help/advice with this toolset would be useful.

  (Note : I’ve also had other issues/questions with this toolset but have started with this one rather than dump a list here)

  Many thanks.

  EDIT - Forgot to mention the stream is of a live feed so things like "duration" and "nb_frames" return "N/A"

• How to determine the correct format when remuxing streams ?

  1er février 2016, par Nyaruko

  I used ffmpeg(libavcodec) to remuxing a incoming h264 stream. The following is the part where I initialize the output format context :

  int ret;
  
  ffmpeg::AVDictionary *opts2 = NULL;
  
  av_dict_set(&opts2, "preset", "medium", 0);
  
  av_dict_set(&opts2, "crf", "29", 0);
  
  av_dict_set(&opts2, "profile", "baseline", 0);
  
  av_dict_set(&opts2, "level", "30", 0);
  
  av_dict_set(&opts2, "maxrate", "200000", 0);
  
  av_dict_set(&opts2, "minrate", "0", 0);
  
  av_dict_set(&opts2, "bufsize", "2000000", 0);
  
  
  
  ffmpeg::AVOutputFormat* fmt = ffmpeg::av_guess_format("mpeg", NULL, NULL);
  
  // Open the context
  
  //---------------------------------------------------------------------
  
  outFormatCtx = ffmpeg::avformat_alloc_context();
  
  if (!outFormatCtx)
  
  {
  
      return false;
  
  }
  
  
  
  //Set the output format
  
  //----------------------------------------------------------------------
  
  outFormatCtx->oformat = fmt;
  
  
  
  // Open the output file
  
  //-------------------------------------
  
  if (!(outFormatCtx->flags & AVFMT_NOFILE))
  
  {
  
      ret = ffmpeg::avio_open2(&outFormatCtx->pb, "Record.avi", AVIO_FLAG_WRITE, NULL, NULL);
  
      if (ret < 0)
  
      {
  
          return false;
  
      }
  
  }
  
  // Create the output stream
  
  // -------------------------------------
  
  ffmpeg::AVStream* out_stream = ffmpeg::avformat_new_stream(outFormatCtx, inputStream->codec->codec);
  
  if (!out_stream) 
  
  {
  
      return false;
  
  }
  
  
  
  //Set the stream parameters
  
  //-------------------------------------
  
  ret = ffmpeg::avcodec_copy_context(out_stream->codec, inputStream->codec);
  
  if (ret < 0) 
  
  {
  
      return false;
  
  }
  
  
  
  // Check then setup for global headers
  
  //-------------------------------------
  
  if (outFormatCtx->oformat->flags & AVFMT_GLOBALHEADER)
  
      out_stream->codec->flags |= CODEC_FLAG_GLOBAL_HEADER;
  
  
  
  av_dump_format(outFormatCtx, 0, "Record.avi", 1);
  
  
  
  
  
  
  
  //Write the header
  
  //--------------------------------------
  
  ret = ffmpeg::avformat_write_header(outFormatCtx, &opts2);
  
  if (ret < 0) 
  
  {
  
      return false;
  
  }

  Then it says I am not setting the VBV buffer size, and remuxing might fail. And the results actually give black screen.

  How could I choose the correct format instead of guessing it ?
  Or How could I set the VBV buffer size ?