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• Node.JS FFMPEG display two videos next to each other

  2 décembre 2020, par James Zammit

  Does anyone have a clue of how to use the node.js wrapper for ffmpeg(fluent-ffmpeg) to merge two videos into one showing one on the left side and another on the right, not concatenation.

  



  Thank you !

  


• How to display frame number starting from one on each frame of a video using ffmpeg ?

  26 octobre 2020, par Misha Homiak

  I need the numbering to start not from zero, but from one

  


  numbering from zero works

  


  drawtext='%{n}'"...


  


  but from one does not work

  


  drawtext='%{n+1}'"...


  


• can write frames to rtsp server, but can't display them in the ffplay or live555 client

  11 octobre 2016, par tankyx

  I am working on a zero latency streaming server, using ffmpeg libraries and I am facing a problem.
  My server is working when using nvenc, I can streaming successfully to my client, which is another computer on LAN. But if I change my encoder to use the libx264 (in order to reduce the latency), the server still write the frames, but the client is facing problems with the sdp header, and more specifically, the media subsession does not seem to be initialized. Therefore, the client crashes.

  The thing is, when I dump the sdp header when using nvenc and libx264, it is actually the same in both case.

  Here is the code I have done to initialize my encoder :

  /*
  
      Init the codec that is used to encode the video.
  
      Init the output format context (aka RTSP uri).
  
  */
  
  FfmpegEncoder::FfmpegEncoder(char *url)
  
  {
  
      AVRational      tmp_time_base;
  
      AVDictionary*   options = NULL;
  
  
  
      this->pCodec = avcodec_find_encoder_by_name("libx264");
  
      if (this->pCodec == NULL)
  
          throw myExceptions("Error: Can't initialize the encoder. FfmpegEncoder.cpp l:9\n");
  
  
  
      this->pCodecCtx = avcodec_alloc_context3(this->pCodec);
  
  
  
      //Alloc output context
  
      if (avformat_alloc_output_context2(&outFormatCtx, NULL, "rtsp", url) < 0)
  
          throw myExceptions("Error: Can't alloc stream output. FfmpegEncoder.cpp l:17\n");
  
  
  
      this->st = avformat_new_stream(this->outFormatCtx, this->pCodec);
  
      this->st->id = this->outFormatCtx->nb_streams - 1;
  
  
  
      if (this->st == NULL)
  
          throw myExceptions("Error: Can't create stream . FfmpegEncoder.cpp l:22\n");
  
  
  
      //Define the framerate of the output. The numerator should stay 1. Denumerator is the framerate we are aiming for.
  
  
  
      tmp_time_base.num = 1;
  
      tmp_time_base.den = 60;
  
  
  
      //TODO : parse these values
  
      this->pCodecCtx->bit_rate = 5000000;
  
      this->pCodecCtx->width = 1280;
  
      this->pCodecCtx->height = 720;
  
      //This set the fps. 60fps at this point.
  
      this->pCodecCtx->time_base = tmp_time_base;
  
      this->st->time_base = tmp_time_base;
  
      //Add a intra frame every 12 frames
  
      this->pCodecCtx->gop_size = 10;
  
      this->pCodecCtx->pix_fmt = AV_PIX_FMT_YUV420P;
  
  
  
      av_opt_set(this->pCodecCtx, "tune", "zerolatency", 0);
  
      av_opt_set(this->pCodecCtx, "vprofile", "main", 0);
  
      av_opt_set(this->pCodecCtx, "preset", "faster", 0);
  
  
  
      //Open Codec, using the context + x264 options
  
      if (avcodec_open2(this->pCodecCtx, this->pCodec, &options) < 0)
  
          throw myExceptions("Error: Can't open the codec. FfmpegEncoder.cpp l:43\n");
  
  
  
      if (avcodec_copy_context(this->st->codec, this->pCodecCtx) != 0) {
  
          throw myExceptions("Error : Can't copy codec context. FfmpegEncoder.cpp : l.46");
  
      }
  
      av_dump_format(this->outFormatCtx, 0, url, 1);
  
  
  
      //write the header needed to start the stream.
  
      if (avformat_write_header(this->outFormatCtx, NULL) != 0)
  
          throw myExceptions("Error: failed to connect to RTSP server. FfmpegEncoder.cpp l:48\n");
  
  }