sloosch / rle

RLE - run length encoding, the simplest approach for lossless compression

##RLE - Run Length Encoding the simplest approach for lossless compression

###Install

npm install rle

###API

Uint32Array RLE.encode(Array<*> stream)
Encodes the given stream of binary data by run length. Each "truthy" element in the stream is treated as 1.
The maximum run length is "limited" to 2^28.
This function further packs the data to reduce the memory usage by nominal 1/4 of the simple RLE approach.

Array<boolean> RLE.decode(Uint32Array stream)
Decodes the stream of RLE data to a binary stream.

Array<number> RLE.encodeSimple(Array<*> stream)
Encodes the given data by run length using the simple approach. Each "truthy" element in the stream is treated as 1. The return value represents a stream of alternating run lengths starting with the length of 0.

Array<boolean> RLE.decodeSimple(Array<number> stream)
Decodes the stream of simple RLE data to a binary stream.

###Example

var rle = require('rle');
var blackAndWhite = getBlackAndWhiteData();
var encoded = rle.encode(blackAndWhite.asArray());

//....

var decoded = rle.decode(encoded);

####Base64

var rleEncoded = rle.encode(data);
base64Encoded = new Buffer(new Uint8Array(rleEncoded.buffer)).toString('base64');

//....

var base64Decoded = new Uint32Array(new Uint8Array(new Buffer(base64Encoded, 'base64')).buffer);
 var rleDecoded = rle.decode(base64Decoded);