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• Streaming h264 from a named pipe to a browser (how to set up the webserver)

  22 août 2020, par Dean

  I have a h264 stream from a webcam : I set up this stream from a C library with mkfifo and I can display it with mplayer with the following line

  


  execlp("xterm", "xterm", "-e", "mplayer", "-demuxer",  "h264es", fifo_name, "-benchmark", "-really-quiet", NULL);


  


  this will open an xterm window with an mplayer instance demuxing a h264 stream from the named pipe into it.

  


  I must, somehow, stream this to a browser (one client is enough). Is there any way to achieve this by setting up a webserver on this same local machine, reading from this named pipe and sending the h264 stream to a remote browser ?

  


• Did not able to pipe output of the ffmpeg using nodejs stdout

  4 mars 2014, par rughimire

  I am not being able to pipe the output of the ffmpeg over a stdout.

  Following are the block of code what I coded so far.

      var http = require('http')
  
      , fs = require('fs') 
  
      var child_process = require("child_process")
  
  
  
      http.createServer(function (req, res) {
  
      console.log("Request:", dump_req(req) , "\n")
  
  
  
      // path of the 
  
      var path = 'test-mp4.mp4'  //test-mp4-long.mp4
  
      , stat = fs.statSync(path)
  
      , total = stat.size
  
  
  
  
  
      var range = req.headers.range
  
      , parts = range.replace(/bytes=/, "").split("-")
  
      , partialstart = parts[0]
  
      , partialend = parts[1]
  
      , start = parseInt(partialstart, 10)
  
      , end = partialend ? parseInt(partialend, 10) : total-1
  
      , chunksize = (end-start)+1
  
  
  
  
  
      console.log('RANGE: ' + start + ' - ' + end + ' = ' + chunksize +  "\n")
  
  
  
  
  
      var ffmpeg = child_process.spawn("ffmpeg",[
  
              "-i", path,             // path
  
              "-b:v" , "64k",         // bitrate to 64k
  
              "-bufsize", "64k", 
  
              "-"                     // Output to STDOUT
  
          ]);
  
  
  
  
  
      //set header
  
      res.writeHead(206
  
      , { 'Content-Range': 'bytes ' + start + '-' + end + '/' + total
  
      , 'Accept-Ranges': 'bytes', 'Content-Length': chunksize
  
      , 'Content-Type': 'video/mp4'
  
      })
  
  
  
      stdout[ params[1] ] = ffmpeg.stdout
  
  
  
      // Pipe the video output to the client response
  
      ffmpeg.stdout.pipe(res);
  
  
  
      console.log("Response", dump_res(res), "\n")
  
      }).listen(1337)

  When i replaced the ffmpeg stuffs from above code, all works fine. Following is the part of the code when i replace the ffmpeg stuffs.

   var file = fs.createReadStream(path, {start: start, end: end})

  And piping like :

  file.pipe(res)

  What wrong I am running ?

  Edit :
  The ffmpeg command works fine. I have tested this through the command line and generating proper output.

• Unable to correctly format opencv raw video data to pipe to ffmpeg to transcode and stream over network

  8 février 2014, par AnthonyAlatorre

  I am trying to pipe the output of a simple OpenCV program to ffmpeg using the following code.
  `

  int main(){
  
  
  
  
  
     VideoCapture cap(-1);
  
     if(!cap.isOpened()){
  
          cout << "Unable to capture webcam."<< endl;
  
          return -1;
  
     }
  
     cap.set( cv::CAP_PROP_FRAME_WIDTH, 640 );
  
     cap.set( cv::CAP_PROP_FRAME_HEIGHT, 480 );
  
  
  
     bool done = false;
  
     while(!done){
  
  
  
          Mat frame;
  
          cap >> frame;
  
          if(frame.empty()){
  
              cout << "Unable to read frame."<< endl;
  
              return -1;
  
          }
  
  
  
          //imshow("frame",frame);
  
          cout << frame.data;
  
          if(cv::waitKey(25) >= 0){ done=true; }
  
  
  
     }
  
  
  
     destroyAllWindows();
  
     return 0;
  
  }

  `
  I have tried using the commands from the following posts : Pipe raw OpenCV images to FFmpeg and How to avoid a growing delay with ffmpeg between sound and raw video data ?. But I still seem to be getting the incorrect output. I have also tried converting the BGR image to YCrCb and then splitting the YCrCb image to merge the same image back together however just switching the Cr & Cb channels. Here's the code for that

     bool done = false;
  
     while(!done){
  
  
  
          Mat frame;
  
          cap >> frame;
  
          if(frame.empty()){
  
              cout << "Unable to read frame."<< endl;
  
              return -1;
  
          }
  
  
  
          //imshow("frame",frame);
  
  //      cout << frame.data;
  
          cvtColor( frame, frame, cv::COLOR_BGR2YCrCb);
  
          vector<mat> ycrcb(3);
  
          split(frame,ycrcb);
  
          vector<mat> newChannels;
  
          newChannels.push_back(ycrcb[0]);
  
          newChannels.push_back(ycrcb[2]);
  
          newChannels.push_back(ycrcb[1]);
  
          Mat res;
  
          merge(newChannels,res);
  
          //cout &lt;&lt; res.data;
  
          //imshow("res",res);
  
          cout &lt;&lt; res.data;
  
  
  
          if(cv::waitKey(25) >= 0){ done=true; }
  
  
  
  
  
  
  
  
  
     }
  
  
  
  
  
  
  
  
  
     destroyAllWindows();
  
     return 0;
  
  }
  
  </mat></mat>

  `

  This seems to stop the video from stuttering and what not however the color is incorrect. However I am not sure if I have to do a 4:2:0 sub sampling on the newly converted YCrCb image. I have also gone through such post for help : Converting YUV into BGR or RGB in OpenCV and How to convert YUV422 (sub sampling) to YUV ?. I also have screenshots of the problems however I do not have enough rep points to post images. Any help would be appreciated and thank you very much for your time.