pcm-convert

Convert data from one pcm-format to another.

Usage

const convert = require('pcm-convert')

//convert data from float32 to uint8 array
let uint8arr = convert([0, 0.1, 0.1, 0], 'float32', 'uint8')

//convert interleaved uint8 to planar float32 array
let float32arr = convert(new Uint8Array([127, 200, 127, 200]), 'uint8 stereo interleaved', 'float32 planar')

//deinterleave keeping the same data type
let int8arr = convert(new Int8Array([-100,100,-100,100]), 'interleaved', 'planar')

//change endianness keeping the same data type
let float32be = convert(new Float32Array([1,.5,-.5,-1]), 'le', 'be')

//use objects as formats
let float64 = convert(float32be, {
	dtype: 'float32',
	channels: 2,
	interleaved: false,
	endianness: 'be'
}, {
	dtype: 'float64',
	interleaved: true,
	endianness: 'le'
})

//skip source format string, convert directly to data format
let uint16 = convert(new Uint8Array([0,255]), 'uint16')

//put data into target container skipping format strings
convert(new Uint8Array([0,255]), new Uint16Array(2))

//full arguments case
let uint16arr = convert([0, 0, 1, 1], 'float32 le stereo planar', 'uint16 interleaved be', new Uint16Array(4))

API

convert(src, srcFormat?, dstFormat?, dst?)

Takes data in src container and converts from srcFormat to dstFormat. Format can be whether a string with tags or an object with properties, see audio-format module. If srcFormat is skipped, it is detected from src. Optionally a destination container can be provided as dst, and in case if dstFormat is skipped, it will be detected from dst.

Source

Source format is inferred from src data type and extended with srcFormat properties. By default source is considered planar mono le. Source data types:

Type	Dtype
Array	float32
Float32Array	float32
Float64Array	float64
ArrayBuffer	uint8
Buffer	uint8
Uint8Array	uint8
Uint8ClampedArray	uint8
Uint16Array	uint16
Uint32Array	uint32
Int8Array	int8
Int16Array	int16
Int32Array	int32

Format

Can be defined as dtype string with tags, eg. 'uint8 interleaved mono le', 'float64 planar quad' (some tags can be skipped), or an object with the following properties:

Property	Meaning
dtype	Data type string: uint8, uint16, uint32, int8, int16, int32, float32, float64, array (only dstFormat), arraybuffer (only dstFormat).
interleaved	Boolean indicating if data has interleaved or planar layout.
channels	Number of channels in source: mono, stereo, quad, 5.1.
endianness	be or le, defaults to OS endianness.

Related

• audio-format - audio format notation parser/stringifier.
• audio-speaker - output data to speaker in node.
• dtype - list of standard data types.

License

© 2017 Dima Yv. MIT License