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    pcm-utilspublic

    node-pcm-utils

    NPM version

    PCM audio utilities for Node.js

    Features

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

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

    • Format conversion - Transform a stream from one PCM format to another (ie. float to int).

    • 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).

    Installation

    Install with npm:

    $ npm install pcm-utils

    or via git:

    $ npm install git+https://github.com/xdissent/node-pcm-utils.git

    Usage

    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),
      
      // Formatter transforms single-channel PCM data from one format to another,
      // 32 bit little-endian float to signed 16 bit little-endian integer in this case.
      formatter = new pcmUtils.Formatter(format, pcmUtils.FMT_S16LE);
     
    // 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);
     
    // Convert the mono mixer output into signed 16 bit little-endian and write to file.
    var fs = require('fs'),
      outFileStream = fs.createWriteStream('/tmp/s16le.pcm');
    formatter.pipe(outFileStream);
    mixer.pipe(formatter);

    Keywords

    none

    install

    npm i pcm-utils

    Downloadsweekly downloads

    6

    version

    0.0.2

    license

    none

    repository

    githubgithub

    last publish

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