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NodeJS native bindings to libmp3lame & libmpg123

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README.md

node-lame

NodeJS native bindings to libmp3lame & libmpg123

For all your async streaming MP3 encoding/decoding needs, there's node-lame! This module hooks into libmp3lame, the library that the lame command uses, to provide an Encoder and Decoder class to NodeJS.

Installation

First you must have the lame dev files installed (lame.h) and the mpg123 dev files installed (mpg123.h).

On OS X with Homebrew, this is as simple as:

$ brew install lame mpg123

Or on Ubuntu, try this:

$ apt-get install libmp3lame-dev libmpg123-dev

Of course you can install those packages from source yourself if you prefer.

Now that the native libraries are installed, we can compile and install node-lame using npm:

$ npm install lame

Example

Here's an example of using node-lame to encode some raw PCM data coming from process.stdin to an MP3 file that gets piped to process.stdout:

var fs = require('fs')
  , lame = require('lame')

// Create the Encoder instance
var encoder = lame.createEncoder({
    channels: 2           // 2 channels (left and right)
  , signed: true          // Signed data values
  , sampleSize: 16        // 16-bit samples
  , sampleRate: 44100     // 44,100 Hz sample rate
  , endianness: 'little'  // Little-endian samples
});

// Raw PCM data from stdin gets piped into the encoder.
process.stdin.pipe(encoder);

// The generated MP3 file gets piped to stdout.
encoder.pipe(process.stdout);

API

Decoder class

Note: Decoder class is still a work-in-progress

The Decoder class is a Stream subclass that accepts MP3 data written to it, and emits raw PCM as data events.

Encoder class

The Encoder class is a Stream subclass that accepts raw PCM data written to it, and emits MP3 data as data events.

Parser class

The Parser class is an EventEmitter subclass that accepts MP3 data being written to it, and emits events as the different structures of the MP3 file are encountered:

  • id3v2 event - fired one time when the ID3v2 data at the beginning of the MP3 file has been parsed. A single Buffer argument is passed to the callbacks.
  • header events - fired multiple times as each MP3 frame header gets written. A single Buffer argument is passed that is the header.
  • frame events - fired multiple times as each complete MP3 frame gets written. A single Buffer argument is passed that is a complete MP3 frame.
  • id3v1 event - fired one time when the ID3v1 data at the end of the MP3 file has been parsed. A single Buffer argument is passed that is the ID3 info.
  • end event - fired one time when then end of the MP3 file is encountered.
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