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• How to terminate cv2.VideoCapture(rtsp_url) call if execution stalls due to RTSP camera issues ?

  23 juillet, par sandeep.ganage

  I have RTSP URLs for 80 total cameras. I am trying to get a screenshot from every camera using cv2.VideoCapture(rtsp_url). I am doing some image processing operations on the captured screenshots from each camera. I have total 80 such URLs for each camera. A sample RTSP URL is :

  


  rtsp://192.168.0.101:554/user=admin_password=oyXv12aW_channel=1_stream=0.sdp?real_stream


  


  Now, sometimes due to the network or other technical issues, some of the cameras temporarily don't function. In that case cv2.VideoCapture(rtsp_url) takes more than 30 seconds to return. In a normal scenario it usually takes 2-3 seconds to return with screenshots. But if a camera is down, it takes too much time. Since my application is running in a for loop on many cameras, I cannot afford to wait. Sometimes the inactive camera count is high and it takes forever to execute the loop. What can be done to reduce the waiting time for cv2.VideoCapture ?

  


  I have also used multiprocessing and have tried terminating processes if they exceed a given time threshold. I don't want to use multiprocessing though it is working very fine. I want to find a solution using only opencv

  


• Pipe output of ffmpeg using nodejs stdout

  21 mai 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.

• 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.