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Add WebAssembly mpeg1 video and mp2 audio decoder
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,106 @@ | ||
| JSMpeg.Decoder.MP2AudioWASM = (function(){ "use strict"; | ||
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| // Based on kjmp2 by Martin J. Fiedler | ||
| // http://keyj.emphy.de/kjmp2/ | ||
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| var MP2WASM = function(options) { | ||
| JSMpeg.Decoder.Base.call(this, options); | ||
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| this.module = options.wasmModule; | ||
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| this.bufferSize = options.audioBufferSize || 128*1024; | ||
| this.bufferMode = options.streaming | ||
| ? JSMpeg.BitBuffer.MODE.EVICT | ||
| : JSMpeg.BitBuffer.MODE.EXPAND; | ||
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| this.sampleRate = 0; | ||
| }; | ||
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| MP2WASM.prototype = Object.create(JSMpeg.Decoder.Base.prototype); | ||
| MP2WASM.prototype.constructor = MP2WASM; | ||
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| MP2WASM.prototype.initializeWasmDecoder = function() { | ||
| if (!this.module.instance) { | ||
| console.warn('JSMpeg: WASM module not compiled yet'); | ||
| return; | ||
| } | ||
| this.instance = this.module.instance; | ||
| this.functions = this.module.instance.exports; | ||
| this.decoder = this.functions._mp2_decoder_create(this.bufferSize, this.bufferMode); | ||
| }; | ||
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| MP2WASM.prototype.destroy = function() { | ||
| this.functions._mp2_decoder_destroy(this.decoder); | ||
| }; | ||
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| MP2WASM.prototype.bufferGetIndex = function() { | ||
| return this.functions._mp2_decoder_get_index(this.decoder); | ||
| }; | ||
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| MP2WASM.prototype.bufferSetIndex = function(index) { | ||
| this.functions._mp2_decoder_set_index(this.decoder, index); | ||
| }; | ||
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| MP2WASM.prototype.bufferWrite = function(buffers) { | ||
| if (!this.decoder) { | ||
| this.initializeWasmDecoder(); | ||
| } | ||
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| var totalLength = 0; | ||
| for (var i = 0; i < buffers.length; i++) { | ||
| totalLength += buffers[i].length; | ||
| } | ||
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| var ptr = this.functions._mp2_decoder_get_write_ptr(this.decoder, totalLength); | ||
| for (var i = 0; i < buffers.length; i++) { | ||
| this.instance.heapU8.set(buffers[i], ptr); | ||
| ptr += buffers[i].length; | ||
| } | ||
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| this.functions._mp2_decoder_did_write(this.decoder, totalLength); | ||
| return totalLength; | ||
| }; | ||
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| MP2WASM.prototype.decode = function() { | ||
| if (!this.decoder) { return; } | ||
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| var decodedBytes = this.functions._mp2_decoder_decode(this.decoder); | ||
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| if (decodedBytes === 0) { | ||
| return false; | ||
| } | ||
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| if (!this.sampleRate) { | ||
| this.sampleRate = this.functions._mp2_decoder_get_sample_rate(this.decoder); | ||
| } | ||
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| if (this.destination) { | ||
| // Create a Float32 View into the modules output channel data | ||
| var leftPtr = this.functions._mp2_decoder_get_left_channel_ptr(this.decoder), | ||
| rightPtr = this.functions._mp2_decoder_get_right_channel_ptr(this.decoder); | ||
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| var leftOffset = leftPtr / Float32Array.BYTES_PER_ELEMENT, | ||
| rightOffset = rightPtr / Float32Array.BYTES_PER_ELEMENT; | ||
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| var left = this.instance.heapF32.subarray(leftOffset, leftOffset + MP2WASM.SAMPLES_PER_FRAME), | ||
| right = this.instance.heapF32.subarray(rightOffset, rightOffset + MP2WASM.SAMPLES_PER_FRAME); | ||
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| this.destination.play(this.sampleRate, left, right); | ||
| } | ||
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| this.advanceDecodedTime(MP2WASM.SAMPLES_PER_FRAME / this.sampleRate); | ||
| return true; | ||
| }; | ||
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| MP2WASM.prototype.getCurrentTime = function() { | ||
| var enqueuedTime = this.destination ? this.destination.enqueuedTime : 0; | ||
| return this.decodedTime - enqueuedTime; | ||
| }; | ||
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| MP2WASM.SAMPLES_PER_FRAME = 1152; | ||
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| return MP2WASM; | ||
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| })(); | ||
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