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• ffmpeg - Making a Clean WAV file

  10 janvier 2021, par Edward

  I'm looking to batch convert a number of files to audio files using ffmpeg for a game called Star Wars: Jedi Knight: Dark Forces II. The problem I'm having is that ffmpeg seems to be doing something that does so that Jedi Knight can't play the sound file.

  



  Jedi Knight accepts plain old PCM WAV files of various ranges, from 5khz to 96khz, 8 and 16 bit, mono and stereo. This sounds plain and simple. Except for that if one were to create a WAV file using MS Sound Recorder, Jedi Knight could not play it. Speculation was that it added something extra to header or something. But it can play a WAV file created by Audacity, GoldWave or ModPlug Tracker to name a few.

  



  So why not ffmpeg ? Am I using the wrong codec or params ? I took an original sound file from the game and performed the following :

  



  ffmpeg -i "orig_thrmlpu2.wav" -f wav -acodec pcm_s16le -ar 22050 -ac 1 "ffmpeg_thrmlpu2.wav"


  



  The ffmpeg version does not play in the game. ffprobe shows that the ffmpeg version has some Metadata which the original doesn't have. What params should I use to try and get the same WAV format as the original ? Mind you, -ar, -ac and bits aren't the important parts.

  



  Here are the files for you to examine : http://www.edwardleuf.org/Games/JK/thrmlpu2.zip

  


• Could not find codec parameter for webcam in ffmpeg

  2 novembre 2018, par Chris S.

  I am trying to save an image with my usb-scanner using ffmpeg and CentOS. For saving images, I am using the following command.

  ffmpeg -f video4linux2 -i /dev/video0 -vframes 1 A.jpg

  This is working for images that consists of mostly dark areas. When I take an image from a white background I always get the following error :

  [video4linux2,v4l2 @ 0x1914c00] Dequeued v4l2 buffer contains corrupted data 
  
  (0 bytes).
  
  Last message repeated 31 times
  
  [video4linux2,v4l2 @ 0x1914c00] decoding for stream 0 failed
  
  [video4linux2,v4l2 @ 0x1914c00] Could not find codec parameters for stream 0 
  
  (Video: mjpeg, none(bt470bg/unknown/unknown), 1600x1200, -5 kb/s): 
  
  unspecified pixel format
  
  Consider increasing the value for the 'analyzeduration' and 'probesize' 
  
  options
  
  /dev/video0: could not find codec parameters

  From the —list-formats command I could archieve that my camera only supports MJPG, no YUV or anything else. My idea was to set the v4l2 settings correctly by :

  v4l2-ctl --set-fmt-video=width=1600,height=1200,pixelformat=MJPG

  But this was not helping in my case. I also though ffmpeg may have some problems with huge files, but as I found out, white images use less space than those dark ones. The scanners name is HoverCam.

  I hope someone can help me with that.

• 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.