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• FFMPEG (Input 8K AAC -> (AAC FLV) youtube streaming noise

  17 septembre 2017, par Biswa Das

  Hello I run a streaming encoder for a non profit cause. Chosen FFMPEG as it’s very simple and doing the job near perfectly however the audio is noisy popping and cracking. Video is crystal clear.

  ffmpeg version N-86950-g1bef008 Copyright (c) 2000-2017 the FFmpeg developers
  built with gcc 7.1.0 (GCC)

  Here is my command.

  ffmpeg -rtsp_transport tcp -i $RTSP_SRC -vcodec copy -af "volume=12dB" -ar 8000 -acodec aac -f flv rtmp://a.rtmp.youtube.com/live2/$DEST_KEY

  However when I just play the stream the noise levels are quite acceptable.

  ffplay -rtsp_transport tcp -i $RTSP_SRC

  What I have tried so far.

  • Change input audio sampling from 8K to 16K (that’s all is supported currently). It made the noise problem much worse. I can’t change it to a native FLV sampling(44100 or 22050 or 11025) at least not yet, the integrated rtsp stream does not support it.)
  • My working theory is during resampling stream noise is getting boosted. So to eliminate that I tried audio copy codec even then there is no significant improvement.

• Transport SEI With Ffmpeg

  29 août 2016, par yuan tian

  I need to transport some data from drone through the help of Ffmpeg.The data includes frame data and some other parameters such as the timing roll/pitch/height/direction of the drone,and when I get the image of the frame,the corresponding parameters should be also pulled out,So I dicede to send these parameters as SEI.
  Then the questions coming,after sending sps pps,I send my own SEI packet，eg :

   if(pkt->size>10&&pkt->data[0] ==0
  
         &&pkt->data[1] ==0
  
         &&pkt->data[2] ==0
  
         &&pkt->data[3] ==1
  
         &&(pkt->data[4] == 103 || pkt->data[4] == 104)){
  
          i++;
  
      }
  
      AVPacket *newPacket = nullptr;
  
      // 0 0 0 1 6 8*16
  
      if(i == 2){
  
          i = 0;
  
          newPacket = (AVPacket *)av_malloc(sizeof(AVPacket));
  
          av_init_packet(newPacket);
  
          newPacket->data = new uint8_t[8];
  
          newPacket->data[0] = 0;
  
          newPacket->data[1] = 0;
  
          newPacket->data[2] = 0;
  
          newPacket->data[3] = 1;
  
          newPacket->data[4] = 6;
  
          newPacket->data[5] = 123;
  
          newPacket->data[6] = 134;
  
          newPacket->data[7] = 128;
  
          newPacket->size = 8;
  
      }
  
   av_write_frame(*it , pkt);
  
          av_free_packet(pkt);
  
          if(newPacket){
  
              av_write_frame(*it , newPacket);
  
              av_free_packet(newPacket);
  
          }

  But,At the receiving terminate,I only find the API:av_read_frame.The API just decode every complete frame from AVFormatContext.My SEI go nothing !
  Besides,I also trying to put my parameters in side_data or metadate of AVFrame,but after rtp tansporting,received AVFrame’s side_data and metadata is 0x00 again.
  Could someone give me some train of thought ?

• OpenCV video writing to named pipe

  21 janvier 2012, par user28667

  I'm trying to send videos created with OpenCV in real-time to user though Apache (user downloads video from a website). I don't need streaming video. I'm just trying to transfer whole video file. My OpenCV program writes video to a named pipe (created with mkfifo) and PHP scrpt reads from it and outputs to user.

  The problem is that pipe-transfered videos doesn't open in Windows. They're shorter exactly at 7072 bytes (checked with different videos). They are not just truncated. The first difference between videos appeared in 5-th byte. And there is no mistake in PHP script. I've checked it using :

  cat fifo.avi > output.avi

  The result was the same. How to make OpenCV write videos to pipes just as to normal files ? Why this happens ? Or is there another way to send videos in real-time to user ?

  P. S. Thanks and sorry for bad English
  P. P. S. I'm creating CvVideoWriter with this code if it matters :

  cvCreateVideoWriter("fifo.avi",CV_FOURCC('M','J','P','G'),25,cvSize(blah blah blah),1)