pcm-utils

PCM audio utilities for Node.js

node-pcm-utils

PCM audio utilities for Node.js

  • Interleaving/deinterleaving - Unzip interleaved PCM data into separate channel streams and vice-versa.

  • Mixing - Mix 2 or more PCM channels into one.

  • Evented - Doesn't block the main loop, thanks to uv_queue_work.

  • Streams2 compatible - Everything's just a pipeable stream.

Note: For sample rate conversion, check out resampler. For playback, try speaker or alsa (which also records).

Install with npm:

$ npm install pcm-utils

or via git:

$ npm install git+https://github.com/xdissent/node-pcm-utils.git
var pcmUtils = require('pcm-utils'),
 
  // The following variables represent the defaults for all constructors. 
  channels = 2,                // 2 channels (left/right) 
  format = pcmUtils.FMT_F32LE, // 32 bit little-endian float 
 
  // Available formats: No big-endian support yet! 
  // 
  // pcmUtils.FMT_F32LE - 32 bit little-endian float 
  // pcmUtils.FMT_F32BE - 32 bit big-endian float **Not currently supported** 
  // pcmUtils.FMT_S16LE - signed 16 bit little-endian integer 
  // pcmUtils.FMT_S16BE - signed 16 bit big-endian integer **Not currently supported** 
  // pcmUtils.FMT_U16LE - unsigned 16 bit little-endian integer 
  // pcmUtils.FMT_U16BE - unsigned 16 bit big-endian integer **Not currently supported** 
 
  // Unzipper deinterleaves PCM data into multiple single-channel streams. 
  unzipper = new pcmUtils.Unzipper(channels, format),
 
  // Zipper interleaves multiple single-channel PCM streams into one. 
  zipper = new pcmUtils.Zipper(channels, format),
  
  // Mixer mixes multiple channels into a single channel stream. 
  mixer = new pcmUtils.Mixer(channels, format);
 
// Read interleaved PCM data from stdin 
process.stdin.pipe(unzipper);
 
// Unzip (de-interleave) it then zip it right back up to stdout 
unzipper.left.pipe(zipper.left);    // or `unzipper.outputs[0].pipe(zipper.inputs[0]); 
unzipper.right.pipe(zipper.right);  // or `unzipper.outputs[1].pipe(zipper.inputs[1]); 
zipper.pipe(process.stdout);
 
// Mix left and right channels and pipe mono to stderr 
unzipper.left.pipe(mixer.left);     // or `unzipper.outputs[0].pipe(mixer.inputs[0]); 
unzipper.right.pipe(mixer.right);   // or `unzipper.outputs[1].pipe(mixer.inputs[1]); 
mixer.pipe(process.stderr);