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• How do I end a pipe ?

  5 septembre 2019, par Leo

  I have trouble using ffprobe from node.js. I need the audio lengths MP3 files. There is an npm package, get-audio-duration for this.

  The package calls ffprobe through an execa command. It works well for .flac files both when when using a filename and a stream. However for .mp3 files it fails for streams.

  I suspected some problems with execa so I checked from the command line (on Windows 10) :

  type file.mp3 | ffprobe -

  (Where I left out the parameters to ffprobe for clarity.)

  This kind of works, but says duration=N/A.

  It looks to me like ffprobe didn’t get the info that the input is finished. Or, it dint care about it. (There is a 4 year old bug report about this on the ffmpeg issue site which was closed for no obvious reason.)

  Is it possible to somehow tell ffprobe that the pipe has ended ?

• How do I end s pipe ?

  5 septembre 2019, par Leo

  I have trouble using ’ffprobe’ from node.js. I need the audio lengths MP3 files. There is an npm package, ’get-audio-duration’ for this.

  The package calls ’ffprobe’ through an ’execa’ command. It works well for .flac files both when when using a filename and a stream. However for .mp3 files it fails for streams.

  I suspected some problems with ’execa’ so I checked from the command line (on Windows 10) :

  type file.mp3 | ffprobe -

  (Where I left out the parameters to ffprobe for clarity.)

  This kind of works, but says duration=N/A.

  It looks to me like ffprobe didn’t get the info that the input is finished. Or, it dint care about it. (There is a 4 year old bug report about this on the ffmpeg issue site which was closed for no obvious reason.)

  Is it possible to somehow tell ffprobe that the pipe has ended ?

• FFMPEG - Pipe PCM to STDOUT in real-time for Node.js

  20 août 2019, par bloom.510

  I am able to stream realtime PCM data from my system’s loopback driver that I can either encode raw or in WAV format using FFMPEG.

  How can I pipe the PCM to stdout as its being recorded in real-time ?

  I’m batting around in the dark here. So far I’ve tried logging stdout in Node.js, as well as creating a named pipe and listening for changes to it. None of these has returned any output.

  The basic shell command captures the audio :

  ffmpeg -f alsa -i loopout -f s16le -acodec pcm_s16le out.raw

  Using child_process.spawn() in Node.js :

  let ffmpeg = spawn('ffmpeg', [
  
      '-f', 'alsa', '-ac', '2', '-ar', '44100', '-i',
  
      'loopout', '-f', 's16le', '-acodec', 'pcm_s16le', 'out.raw',
  
  ]);

  However :

  // this never logs anything
  
  ffmpeg.stdout.on('data', (data) => {
  
      console.log(data.toString());
  
  });
  
  
  
  // this outputs what you would see in the terminal window
  
  ffmpeg.stderr.on('data', (data) => {
  
      console.log(data.toString());
  
  });

  Is there a way to access a readable stream of this file as its being created ?

  Or perhaps there is a way to stream the PCM to an RTP server and forward it as a buffer over UDP to an Express server ?

  Whatever the methodology is, the ultimate goal is to access it as a stream in Node.js and convert it into an ArrayBuffer.