giuliomoro@15: // Decode and perform WAVE file byte level manipulation
giuliomoro@15: 
giuliomoro@15: find_subarray = function(arr,subarr) {
giuliomoro@15:     var arr_length = arr.length;
giuliomoro@15:     var subarr_length = subarr.length;
giuliomoro@15:     var last_check_index = arr_length - subarr_length;
giuliomoro@15:     
giuliomoro@15:     positionLoop:
giuliomoro@15:     for (var i=0; i <= last_check_index; i++)
giuliomoro@15:     {
giuliomoro@15:         for (var j=0; j< subarr_length; j++)
giuliomoro@15:         {
giuliomoro@15:             if (arr[i + j] !== subarr[j]) {
giuliomoro@15:                 continue positionLoop;
giuliomoro@15:             }
giuliomoro@15:         }
giuliomoro@15:         return i;
giuliomoro@15:     }
giuliomoro@15:     return -1;
giuliomoro@15: };
giuliomoro@15: 
giuliomoro@15: function convertToInteger(arr) {
giuliomoro@15:     var value = 0;
giuliomoro@15:     for (var i=0; i<arr.length; i++)
giuliomoro@15:     {
giuliomoro@15:         value += arr[i]<<(i*8);
giuliomoro@15:     }
giuliomoro@15:     return value;
giuliomoro@15: }
giuliomoro@15: function convertToString(arr) {
giuliomoro@15:     var str = "";
giuliomoro@15:     for (var i=0; i<arr.length; i++)
giuliomoro@15:     {
giuliomoro@15:         str = str.concat(String.fromCharCode(arr[i]));
giuliomoro@15:     }
giuliomoro@15:     return str;
giuliomoro@15: }
giuliomoro@15: 
giuliomoro@15: function WAVE()
giuliomoro@15: {
giuliomoro@15:     // The WAVE file object
giuliomoro@15:     this.status == 'WAVE_DECLARED'
giuliomoro@15:     
giuliomoro@15:     this.decoded_data = null;
giuliomoro@15:     
giuliomoro@15:     this.RIFF = String(); //ChunkID
giuliomoro@15: 	this.size; //ChunkSize
giuliomoro@15: 	this.FT_Header; //Format
giuliomoro@15: 	this.fmt_marker; //Subchunk1ID
giuliomoro@15: 	this.formatDataLength; //Subchunk1Size
giuliomoro@15: 	this.type; //AudioFormat
giuliomoro@15: 	this.num_channels; //NumChannels
giuliomoro@15: 	this.sample_rate; //SampleRate
giuliomoro@15: 	this.byte_rate; //ByteRate
giuliomoro@15: 	this.block_align; //BlockAlign
giuliomoro@15: 	this.bits_per_sample; //BitsPerSample
giuliomoro@15: 	this.data_header; //Subchunk2ID
giuliomoro@15: 	this.data_size; //Subchunk2Size
giuliomoro@15:     this.num_samples;
giuliomoro@15:     
giuliomoro@15:     this.open = function(IOArrayBuffer)
giuliomoro@15:     {
giuliomoro@15:         var IOView8 = new Uint8Array(IOArrayBuffer);
giuliomoro@15:         this.RIFF = convertToString(IOView8.subarray(0,4));
giuliomoro@15:         if (this.RIFF != 'RIFF')
giuliomoro@15:         {
giuliomoro@15:             console.log('WAVE ERR - Not a RIFF file');
giuliomoro@15:             return 1;
giuliomoro@15:         }
giuliomoro@15:         this.size = convertToInteger(IOView8.subarray(4,8));
giuliomoro@15:         this.FT_Header = convertToString(IOView8.subarray(8,12));
giuliomoro@15:         this.fmt_marker = convertToString(IOView8.subarray(12,16));
giuliomoro@15:         this.formatDataLength = convertToInteger(IOView8.subarray(16,20));
giuliomoro@15:         this.type = convertToInteger(IOView8.subarray(20,22));
giuliomoro@15:         this.num_channels = convertToInteger(IOView8.subarray(22,24));
giuliomoro@15:         this.sample_rate = convertToInteger(IOView8.subarray(24,28));
giuliomoro@15:         this.byte_rate = convertToInteger(IOView8.subarray(28,32));
giuliomoro@15:         this.block_align = convertToInteger(IOView8.subarray(32,34));
giuliomoro@15:         this.bits_per_sample = convertToInteger(IOView8.subarray(34,36));
giuliomoro@15:         
giuliomoro@15:         // Find the data header first
giuliomoro@15:         var data_start = find_subarray(IOView8,[100, 97, 116, 97]);
giuliomoro@15:         
giuliomoro@15:         this.data_header = convertToString(IOView8.subarray(data_start,data_start+4));
giuliomoro@15:         this.data_size = convertToInteger(IOView8.subarray(data_start+4,data_start+8));
giuliomoro@15:         
giuliomoro@15:         this.num_samples = this.data_size / this.block_align;
giuliomoro@15:         
giuliomoro@15:         this.decoded_data = [];
giuliomoro@15:         if (this.type != 1 && this.type != 3) {
giuliomoro@15:             console.log("Neither PCM nor IEEE float, cannot decode");
giuliomoro@15:             return 1;
giuliomoro@15:         }
giuliomoro@15:         for (var c=0; c<this.num_channels; c++)
giuliomoro@15:         {
giuliomoro@15:             this.decoded_data.push(new Float32Array(this.num_samples));
giuliomoro@15:         }
giuliomoro@15:         var sampleDataOffset = data_start+8;
giuliomoro@15:         
giuliomoro@15:         // Now need to decode the data from sampleDataOffset
giuliomoro@15:         // Data is always interleved
giuliomoro@15:         var data_view;
giuliomoro@15:         if (this.type == 3)
giuliomoro@15:         {
giuliomoro@15:             // Already in float
giuliomoro@15:             if (this.bits_per_sample == 32) {
giuliomoro@15:                 data_view = new Float32Array(IOArrayBuffer.slice(sampleDataOffset,sampleDataOffset+this.data_size));
giuliomoro@15:             } else if (this.bits_per_sample == 64) {
giuliomoro@15:                 data_view = new Float64Array(IOArrayBuffer.slice(sampleDataOffset,sampleDataOffset+this.data_size));
giuliomoro@15:             }
giuliomoro@15:         } else if (this.type == 1)
giuliomoro@15:         {
giuliomoro@15:             data_view = new Float32Array(this.num_samples*this.num_channels);
giuliomoro@15:             integerConvert(new Uint8Array(IOArrayBuffer.slice(sampleDataOffset,sampleDataOffset+this.data_size)),data_view,this.bits_per_sample/8);
giuliomoro@15:         }
giuliomoro@15:         deInterlace(data_view,this.decoded_data);
giuliomoro@15:         return 0;
giuliomoro@15:     };
giuliomoro@15: }
giuliomoro@15: 
giuliomoro@15: function deInterlace(src_array, dst_array)
giuliomoro@15: {
giuliomoro@15:     var number = src_array.length;
giuliomoro@15:     var channels = dst_array.length;
giuliomoro@15:     var channel_index = 0;
giuliomoro@15:     var dst_index = 0;
giuliomoro@15:     for (var n=0; n<number; n++)
giuliomoro@15:     {
giuliomoro@15:         dst_array[channel_index][dst_index] = src_array[n];
giuliomoro@15:         channel_index++;
giuliomoro@15:         if (channel_index >= channels) {
giuliomoro@15:             channel_index = 0;
giuliomoro@15:             dst_index++;
giuliomoro@15:         }
giuliomoro@15:     }
giuliomoro@15: }
giuliomoro@15: 
giuliomoro@15: function integerConvert(srcView,dstView,srcBytes)
giuliomoro@15: {
giuliomoro@15:     //Convert integers of a Uint8Array of certain byte length into a Float32Array
giuliomoro@15:     var number = dstView.length;
giuliomoro@15:     var outBits = srcBytes*8;
giuliomoro@15:     var endShift = 32 - outBits;
giuliomoro@15:     if (srcView.length != dstView.length*srcBytes)
giuliomoro@15:     {
giuliomoro@15:         return -1;
giuliomoro@15:     }
giuliomoro@15:     for (var n=0; n<number; n++)
giuliomoro@15:     {
giuliomoro@15:         var srcIndex = n*srcBytes;
giuliomoro@15:         var intData = convertToInteger(srcView.subarray(srcIndex,srcIndex+srcBytes));
giuliomoro@15:         intData = (intData << (endShift));
giuliomoro@15:         dstView[n] = intData / 2147483648;
giuliomoro@15:     }
giuliomoro@15: }