101 lines
2.4 KiB
JavaScript
101 lines
2.4 KiB
JavaScript
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/**
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* Module dependencies.
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*/
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var assert = require('assert');
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var Parser = require('stream-parser');
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var inherits = require('util').inherits;
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var debug = require('debug')('icecast:reader');
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var Transform = require('stream').Transform;
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// for node v0.8.x support, remove after v0.12.x
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if (!Transform) Transform = require('readable-stream/transform');
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/**
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* Module exports.
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*/
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module.exports = Reader;
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/**
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* The metabyte must be multiplied by META_BLOCK_SIZE to get the real
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* metadata byte-length.
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*
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* @api private
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*/
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var META_BLOCK_SIZE = 16;
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/**
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* Icecast stream reader. This is a duplex stream that emits "metadata" events in
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* addition to stripping out the metadata itself from the output data. The result
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* is clean (audio and/or video) data coming out of the stream.
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*
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* @param {Number} metaint the number of bytes in between "metadata" blocks (usually the `Icy-MetaInt` HTTP header).
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* @param {Object} opts optional options object
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* @api public
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*/
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function Reader (metaint, opts) {
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if (!(this instanceof Reader)) {
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return new Reader(metaint, opts);
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}
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if (!isFinite(metaint)) {
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throw new TypeError('Reader requires a "metaint" number');
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}
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Transform.call(this, opts);
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this.metaint = +metaint;
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this._passthrough(this.metaint, this._onRawData);
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debug('created new Reader instance with "metaint": %d', this.metaint);
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}
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inherits(Reader, Transform);
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/**
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* Mixin `Parser`.
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*/
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Parser(Reader.prototype);
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/**
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* Called after "metaint" bytes have been passed through.
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*
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* @api private
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*/
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Reader.prototype._onRawData = function () {
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debug('_onRawData()');
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this._bytes(1, this._onMetaByte);
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};
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/**
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* Called when the "metabyte" has been received.
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*
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* @api private
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*/
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Reader.prototype._onMetaByte = function (chunk) {
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assert(chunk.length === 1);
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var length = chunk[0] * META_BLOCK_SIZE;
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debug('_onMetaByte: metabyte: %d, metalength: %d', chunk[0], length, chunk);
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if (length > 0) {
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// we have metadata to parse
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this._bytes(length, this._onMetaData);
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} else {
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// not metadata this time around, back to serving raw data chunks
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this._passthrough(this.metaint, this._onRawData);
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}
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};
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/**
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* Called once all the metadata has been buffered for this pass.
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*
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* @api private
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*/
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Reader.prototype._onMetaData = function (chunk) {
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debug('_onMetaData (chunk.length: %d)', chunk.length);
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this.emit('metadata', chunk);
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this._passthrough(this.metaint, this._onRawData);
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};
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