sox-stream

A stream wrapper around SoX. Transcode audio streams easily!

Why

The other implementations I found felt klunky to use. This module implements a streaming interface. (If you don't know how to use streams, I recommend reading the stream handbook.)

Examples

Simple transcode:

var sox = require('sox-stream')
var fs  = require('fs')

fs.createReadStream('song.wav')
	.pipe( sox({ output: { type: 'flac' } }) )
	.pipe( fs.createWriteStream('song.flac') )

Lower volume:

var sox = require('sox-stream')
var fs  = require('fs')

var src = fs.createReadStream('song.flac')
var lowerVolume = sox({ input: { volume: 0.8 }, output: { type: flac }})
var dest = fs.createWriteStream('song2.flac')

src.pipe(lowerVolume).pipe(dest)

Transcode with options and error handling:

var sox = require('sox-stream')
var fs  = require('fs')

var src = fs.createReadStream('song.ogg')
var transcode = sox({
	output: {
		bits: 16,
		rate: 44100,
		channels: 2,
		type: 'wav'
	}
})
var dest = fs.createWriteStream('song.wav')
src.pipe(transcode).pipe(dest)

transcode.on('error', function (err) {
	console.log('oh no! ' + err.message)
})

API

var sox = require('sox-stream')

var transform = sox(options)

• options object required - The following parameters are supported:
  • soxPath string optional - The path to SoX. E.g. 'C:\Program Files\Sox\sox.exe'. Defaults to 'sox', which works if the SoX binary is in your path.
  • global object optional - Global SoX options
  • input object optional - These options will be used to interpret the incoming stream.
  • output object required - These options will be used to format the outgoing stream. When an output option isn't supplied, the output file will have the same format as the input file where possible. (Except type, which you must always pass in.)
  • effects string|array of strings/numbers optional
• Returns transform, a stream to pipe data through. The stream emits 'error' events when there is an error.

options object

An object of options. Every option is optional except options.output.type is required.

If you want an exhaustive list of each SoX option in depth, take a look at the SoX documentation.

Internally, these options are transformed into the command-line arguments passed to a SoX child process.

options.global object|array of strings/numbers

You can supply an array of strings/numbers, or an object that will be transformed into an array of strings/numbers using hash-to-array.

Currently, sox-stream only supports one input file, so some of these options don't really make sense.

Command(s)	Functionality
{ buffer: BYTES }	Set the size of all processing buffers (default 8192)
{ combine: 'concatenate' }	Concatenate all input files (default for sox, rec)
{ combine: 'sequence' }	Sequence all input files (default for play)
'-m', { m: true }, { combine: 'mix' }	Mix multiple input files (instead of concatenating)
{ combine: 'mix-power' }	Mix to equal power (instead of concatenating)
'-M', { M: true }, { combine: 'merge' }	Merge multiple input files (instead of concatenating)
'-T', { T: true }, { combine: 'multiply' }	Multiply samples of corresponding channels from all input files (instead of concatenating)
'-D', { D: true }, { 'no-dither': true }	Don't dither automatically
{ 'effects-file': FILENAME }	File containing effects and options
'-G', { G: true }, { guard: true }	Use temporary files to guard against clipping
{ input-buffer: BYTES }	Override the input buffer size (default: same as --buffer; 8192)
'--norm', { norm: true }	Guard (see --guard) & normalise
{ play-rate-arg: ARG }	Default rate argument for auto-resample with `play'
{ plot: 'gnuplot', 'octave' }	Generate script to plot response of filter effect
{ 'replay-gain': 'track', 'album', 'off' }	Default: 'off' (sox, rec), track (play)
'-R', { R: true }	Use default random numbers (same on each run of SoX)
'--single-threaded', { 'single-threaded': true }	Disable parallel effects channels processing
{ temp: DIRECTORY }	Specify the directory to use for temporary files

var transform = sox({
	global: {
		buffer: 4096,
		norm: true,
		'single-threaded': true
	},
	output: { type: 'ogg' }
})

options.input / options.output object|array of strings/numbers

You can supply an array of strings/numbers, or an object that will be transformed into an array of strings/numbers using hash-to-array.

Input	Output	Command(s)	Functionality
✓	X	{ v: FACTOR }, { volume: FACTOR }	Input file volume adjustment factor (Floating point number between 0 and 1)
✓	X	{ ignore-length: true }	Ignore input file length given in header; read to EOF
✓	✓	{ t: FILETYPE }, { type: FILETYPE }	Audio file type. E.g. 'wav', 'ogg'
✓	✓	{ e: ENCODING }, { encoding: ENCODING }	ENCODING can be 'signed-integer', 'unsigned-integer', 'floating-point', 'mu-law', 'a-law', 'ima-adpcm', 'ms-adpcm', or 'gsm-full-rate'
✓	✓	'-b', { b: BITS }, { bits: BITS }	Encoded sample size in bits, A.K.A. the bit depth. E.g. 16, 24. (Not applicable to complex encodings such as MP3 or GSM.)
✓	✓	'-N', { N: true }, { 'reverse-nibbles': true }	Encoded nibble-order
✓	✓	'-X', { X: true }, { 'reverse-bits': true }	Encoded bit-order
✓	✓	'-L', { endian: 'little' }, { L: true }	Encoded byte-order: Little endian
✓	✓	'-B', { endian: 'big' }, { B: true }	Encoded byte-order: Big endian
✓	✓	'-x', { endian: 'swap' }, { x: true }	Encoded byte-order: swap means opposite to default
✓	✓	{ c: CHANNELS }, { channels: CHANNELS }	Number of channels of audio data. E.g. 2 for stereo
✓	✓	'--no-glob', { 'no-glob': true }	Don't `glob' wildcard match the following filename
✓	✓	{ r: RATE }, { rate: RATE }	Sample rate of audio. E.g. 44100, 48000
X	✓	{ C: FACTOR }, { compression: FACTOR }	Compression factor. (Might be bitrate, depending on the file type.) See SoX format docs for more info.
X	✓	{ 'add-comment': TEXT }	Append output file comment
X	✓	{ comment: TEXT }	Specify comment text for the output file
X	✓	{ 'comment-file': FILENAME }	File containing comment text for the output file

var transform = sox({
	input: [
		[ '--volume', 1.1 ],
		[ '--endian', 'big' ],
		[ '--no-glob' ]
	],
	output: { type: 'ogg' }
})
// same as
var transform = sox({
	input: {
		volume: 1.1,
		endian: 'big',
		'no-glob': true
	],
	output: [
		'--type', 'ogg'
	]
})
// same as
var transform = sox({
	input: '--volume 1.1 --endian big --no-glob',
	output: '--type ogg'
})

options.effects string|array of strings/numbers/arrays

Please see the SoX Documentation on Effects to see all the options.

Pass them into sox-stream like this:

var transform = sox({
	input: { type: 'ogg' },
	output: { type: 'wav' },


	effects: 'speed 1.5 swap'
	// same as
	effects: [
		'speed 1.5 swap'
	]
	// same as
	effects: [
		'speed', 1.5,
		'swap'
	]
	// same as
	effects: [
		[ 'speed', '1.5' ],
		'swap'
	]
})

Install

• Install SoX. You can download it, or you can do apt-get install sox
• Install this package with npm: npm install sox-stream

Test

To run the tests, you must have SoX in your PATH. Then run: npm test

I run the tests using SoX 14.4.2, but other versions of SoX should work as well.

Codec Support

FLAC

• Problem: FLAC was disabled accidentally in 14.4.1 (SourceForge default). [Stack Overflow]
• Solution: Install SoX 14.4.2.

MP3

• Problem: MP3 was proprietary.
• Solution: Compile the LAME encoder, and/or the MAD decoder.
• Links:
  • Windows (Precompiled)
  • Windows (How-To)
  • Ubuntu (How-To)
  • Ubuntu (How-To) 2
  • CentOS (How-To)

License

MIT