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• Is there a way to "replace" FFmpeg stream with another file ? [closed]

  6 novembre 2023, par brizgalka

  I'm using FFmpeg as a transcoder and VLC as a retranslator for my IPTV streaming utility.

  


  At the moment, I make a stream by looping the concatenation of a few clips I rewrite with my NodeJS program.

  


  nested.txt

  


  file clip1.mkv
file clip2.mkv


  


  ffmpeg command (simplified)
ffmpeg -stream_loop 1 -f concat -i nested.txt -listen 1 -f mp4 http://localhost:8081

  


  But I wonder if it is possible for me to simply terminate FFmpeg process and start a new one with another input file without interrupting VLC from reading the stream. I would actually accept the answer even if you could provide me with an alternative retranslator instead of VLC that has this feature.

  


  I tried to terminate the FFmpeg process and quickly start a new one softwarely. However, it seems that terminated process manages to send some kind of "end of the stream" signal to client before it actually closes.

  


• Where does facebook compress its video and Images, Client side or server Side

  20 juillet 2021, par Mohan

  We know that Facebook compress its video and images when we upload it. My question is where does this happen ? If I am uploading the video from my mobile device, does Facebook compress the video using Media Codec or FFmPeg library on native android device (like it is done by WhatsApp) or It first uploads the video on server and then compress the video on server ?

  


• skip frame rendering if falling behind

  9 novembre 2016, par Brannon

  I have the code below that uses ffmpeg libraries (v3.1.4 with the Autogen wrapper) to render RTSP video in my application. The code works very well generally. However, the receptical.Write method is not particularly performant. On slow machines my video rendering starts to fall behind. Eventually my buffers fill up and I start to see video corruption. How can I change the code below to skip frames when it starts to fall behind ? If there are multiple frames ready, I really only care to show the frame most recently available — this is live video after all. I believe that the avcodec_send_packet and avcodec_receive_frame methods are approximately 1-to-1.

  while (!token.IsCancellationRequested)
  
  {
  
      if (ffmpeg.av_read_frame(pFormatContext, pPacket) != 0)
  
      {
  
          // end of the stream
  
          ffmpeg.av_packet_unref(pPacket);
  
          ffmpeg.av_frame_unref(pDecodedFrame);
  
          break;
  
      }
  
  
  
      if (pPacket->stream_index != pStream->index || (pPacket->flags & ffmpeg.AV_PKT_FLAG_CORRUPT) > 0)
  
      {
  
          // this should never happen; we only subscribe to one stream
  
          // and I believe corrupt packets are automatically discarded
  
          ffmpeg.av_packet_unref(pPacket);
  
          ffmpeg.av_frame_unref(pDecodedFrame);
  
          continue;
  
      }
  
  
  
      var sendResult = ffmpeg.avcodec_send_packet(pCodecContext, pPacket);
  
      if (sendResult < 0)
  
      {
  
          // one of the possible results is a "buffer full", but I don't think that should happen as long as we call 1-to-1 receive_frame
  
          ffmpeg.av_packet_unref(pPacket);
  
          ffmpeg.av_frame_unref(pDecodedFrame);
  
          _logger.Warn("Failure in FFmpeg avcodec_send_packet: " + sendResult);
  
          break;
  
      }
  
  
  
      while (ffmpeg.avcodec_receive_frame(pCodecContext, pDecodedFrame) == 0)
  
      {
  
          var src = &pDecodedFrame->data0;
  
          var dst = &pConvertedFrame->data0;
  
          var srcStride = pDecodedFrame->linesize;
  
          var dstStride = pConvertedFrame->linesize;
  
          ffmpeg.sws_scale(pConvertContext, src, srcStride, 0, height, dst, dstStride);
  
  
  
          sbyte* convertedFrameAddress = pConvertedFrame->data0;
  
  
  
          int linesize = dstStride[0];
  
  
  
          if (receptical == null)
  
          {
  
              receptical = writableBitampCreationCallback.Invoke(new DetectedImageDimensions {Width = width, Height = height, Format = DetectedPixelFormat.Bgr24, Linesize = linesize});
  
          }
  
  
  
          var imageBufferPtr = new IntPtr(convertedFrameAddress);
  
          receptical.Write(width, height, imageBufferPtr, linesize);
  
  
  
          ffmpeg.av_frame_unref(pDecodedFrame);
  
      }
  
      ffmpeg.av_packet_unref(pPacket);
  
  }