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• How to successfully parse the output of FFMpeg in NodeJS

  22 mai 2017, par Danny SMc

  So I have seen a lot of topics on FFMPeg and it’s a great tool I learnt about today, but I have spent the day perfecting the command and now am a little stuck with the NodeJS part.

  In essence the command does the following : take input from a Mac OSX webcam, and then stream it to a web-socket. Now I looked at a lot of the NodeJS libraries but I couldn’t find one that did what I need ; or did not understand how to. Here is an example of the command that I am using :

  ffmpeg -f avfoundation -framerate 30 -video_size 640x480 -pix_fmt uyvy422 -i "0:1" -f mpegts -codec:v mpeg1video -s 640x480 -b:v 1000k -bf 0 http://localhost:8081/stream

  This does everything I need for the streaming side of things, but I wish to call it via NodeJS, and then be able to monitor the log, and parse the data that comes back for example :

  frame= 4852 fps= 30 q=6.8 size=   30506kB time=00:02:41.74 bitrate=1545.1kbits/s speed=   1x    \r

  and use it to get a JSON array back for me to output to a webpage.

  Now all I am doing is working on ways of actually parsing the data, and I have looked at lots of other answers for things like this, but I can’t seem to split/replace/regex it. I can’t get anything but a long string from it.

  Here is the code I am using (NodeJS) :

  var ffmpeg = require('child_process').spawn('/usr/local/Cellar/ffmpeg/3.3.1/bin/ffmpeg', ['-f', 'avfoundation', '-framerate', '30', '-video_size', '640x480', '-pix_fmt', 'uyvy422', '-i', '0:1', '-f', 'mpegts', '-codec:v', 'mpeg1video', '-s', '640x480', '-b:v', '1000k', '-bf', '0', 'http://localhost:8081/test']);
  
  
  
  ffmpeg.on('error', function (err) {
  
      console.log(err);
  
  });
  
  
  
  ffmpeg.on('close', function (code) {
  
      console.log('ffmpeg exited with code ' + code);
  
  });
  
  
  
  ffmpeg.stderr.on('data', function (data) {
  
      // console.log('stderr: ' + data);
  
      var tData = data.toString('utf8');
  
      // var a = tData.split('[\\s\\xA0]+');
  
      var a = tData.split('\n');
  
      console.log(a);
  
  });
  
  
  
  ffmpeg.stdout.on('data', function (data) {
  
      var frame = new Buffer(data).toString('base64');
  
      // console.log(frame);
  
  });

  I have tried splitting with new lines, carridge return, spaces, tabs, but I just can’t seem to get a basic array of bits, that I can work with.

  Another thing to note, is you will notice the log comes back via stderr, I have seen this online and apparently it does it for a lot of people ? So I am not sure what the deal is with that ? but the code is is the sdterr callback.

  Any help is very appreciated as I am truly confused on what I am doing wrong.

  Thanks.

• How to successfully parse the output of FFMpeg in NodeJS

  28 juillet 2022, par Dahknee

  So I have seen a lot of topics on FFMPeg and it's a great tool I learnt about today, but I have spent the day perfecting the command and now am a little stuck with the NodeJS part.

  



  In essence the command does the following : take input from a Mac OSX webcam, and then stream it to a web-socket. Now I looked at a lot of the NodeJS libraries but I couldn't find one that did what I need ; or did not understand how to. Here is an example of the command that I am using :

  



  ffmpeg -f avfoundation -framerate 30 -video_size 640x480 -pix_fmt uyvy422 -i "0:1" -f mpegts -codec:v mpeg1video -s 640x480 -b:v 1000k -bf 0 http://localhost:8081/stream


  



  This does everything I need for the streaming side of things, but I wish to call it via NodeJS, and then be able to monitor the log, and parse the data that comes back for example :

  



  frame= 4852 fps= 30 q=6.8 size=   30506kB time=00:02:41.74 bitrate=1545.1kbits/s speed=   1x    \r


  



  and use it to get a JSON array back for me to output to a webpage.

  



  Now all I am doing is working on ways of actually parsing the data, and I have looked at lots of other answers for things like this, but I can't seem to split/replace/regex it. I can't get anything but a long string from it.

  



  Here is the code I am using (NodeJS) :

  



  var ffmpeg = require('child_process').spawn('/usr/local/Cellar/ffmpeg/3.3.1/bin/ffmpeg', ['-f', 'avfoundation', '-framerate', '30', '-video_size', '640x480', '-pix_fmt', 'uyvy422', '-i', '0:1', '-f', 'mpegts', '-codec:v', 'mpeg1video', '-s', '640x480', '-b:v', '1000k', '-bf', '0', 'http://localhost:8081/test']);

ffmpeg.on('error', function (err) {
    console.log(err);
});

ffmpeg.on('close', function (code) {
    console.log('ffmpeg exited with code ' + code);
});

ffmpeg.stderr.on('data', function (data) {
    // console.log('stderr: ' + data);
    var tData = data.toString('utf8');
    // var a = tData.split('[\\s\\xA0]+');
    var a = tData.split('\n');
    console.log(a);
});

ffmpeg.stdout.on('data', function (data) {
    var frame = new Buffer(data).toString('base64');
    // console.log(frame);
});


  



  I have tried splitting with new lines, carridge return, spaces, tabs, but I just can't seem to get a basic array of bits, that I can work with.

  



  Another thing to note, is you will notice the log comes back via stderr, I have seen this online and apparently it does it for a lot of people ? So I am not sure what the deal is with that ? but the code is is the sdterr callback.

  



  Any help is very appreciated as I am truly confused on what I am doing wrong.

  



  Thanks.

  


• Maintain PTS on .ts file resize

  5 février 2020, par PRMan

  Let’s say I have a .ts file from an existing HLS and I simply want to resize it. For example, to create a second lower-resolution stream that can be switched when bandwidth is poor.

  ffmpeg -i video1080_1.ts -vf "scale=1280:720" video720_1.ts

  How do I ensure that video720_1.ts starts at the exact same PTS as video1080_1.ts ? I haven’t changed the rate, so it will play fine as long as it starts at the exact same PTS.

  I have tried a lot of things (vsync, copyts, etc.) but none of them give me the exact same number.

  Also, I tried adding -copyts -vsync 2 -muxdelay 0 -muxpreload 0 and that got it closer, but still off by 1100 (4422778 vs 4423680).