n@482: // Decode and perform WAVE file byte level manipulation
n@482: 
n@482: find_subarray = function(arr,subarr) {
n@482:     var arr_length = arr.length;
n@482:     var subarr_length = subarr.length;
n@482:     var last_check_index = arr_length - subarr_length;
n@482:     
n@482:     positionLoop:
n@482:     for (var i=0; i <= last_check_index; i++)
n@482:     {
n@482:         for (var j=0; j< subarr_length; j++)
n@482:         {
n@482:             if (arr[i + j] !== subarr[j]) {
n@482:                 continue positionLoop;
n@482:             }
n@482:         }
n@482:         return i;
n@482:     }
n@482:     return -1;
n@482: };
n@482: 
n@515: function convertToInteger(arr) {
n@515:     var value = 0;
n@515:     for (var i=0; i<arr.length; i++)
n@515:     {
n@515:         value += arr[i]<<(i*8);
n@515:     }
n@515:     return value;
n@515: }
n@515: function convertToString(arr) {
n@515:     var str = "";
n@515:     for (var i=0; i<arr.length; i++)
n@515:     {
n@515:         str = str.concat(String.fromCharCode(arr[i]));
n@515:     }
n@515:     return str;
n@515: }
n@515: 
n@482: function WAVE()
n@482: {
n@482:     // The WAVE file object
n@482:     this.status == 'WAVE_DECLARED'
n@482:     
n@482:     this.decoded_data = null;
n@482:     
n@482:     this.RIFF = String(); //ChunkID
n@482: 	this.size; //ChunkSize
n@482: 	this.FT_Header; //Format
n@482: 	this.fmt_marker; //Subchunk1ID
n@482: 	this.formatDataLength; //Subchunk1Size
n@482: 	this.type; //AudioFormat
n@482: 	this.num_channels; //NumChannels
n@482: 	this.sample_rate; //SampleRate
n@482: 	this.byte_rate; //ByteRate
n@482: 	this.block_align; //BlockAlign
n@482: 	this.bits_per_sample; //BitsPerSample
n@482: 	this.data_header; //Subchunk2ID
n@482: 	this.data_size; //Subchunk2Size
n@482:     this.num_samples;
n@482:     
n@482:     this.open = function(IOArrayBuffer)
n@482:     {
n@482:         var IOView8 = new Uint8Array(IOArrayBuffer);
n@515:         this.RIFF = convertToString(IOView8.subarray(0,4));
n@482:         if (this.RIFF != 'RIFF')
n@482:         {
n@482:             console.log('WAVE ERR - Not a RIFF file');
n@482:             return 1;
n@482:         }
n@515:         this.size = convertToInteger(IOView8.subarray(4,8));
n@515:         this.FT_Header = convertToString(IOView8.subarray(8,12));
n@515:         this.fmt_marker = convertToString(IOView8.subarray(12,16));
n@515:         this.formatDataLength = convertToInteger(IOView8.subarray(16,20));
n@515:         this.type = convertToInteger(IOView8.subarray(20,22));
n@515:         this.num_channels = convertToInteger(IOView8.subarray(22,24));
n@515:         this.sample_rate = convertToInteger(IOView8.subarray(24,28));
n@515:         this.byte_rate = convertToInteger(IOView8.subarray(28,32));
n@515:         this.block_align = convertToInteger(IOView8.subarray(32,34));
n@515:         this.bits_per_sample = convertToInteger(IOView8.subarray(34,36));
n@482:         
n@482:         // Find the data header first
n@482:         var data_start = find_subarray(IOView8,[100, 97, 116, 97]);
n@482:         
n@515:         this.data_header = convertToString(IOView8.subarray(data_start,data_start+4));
n@515:         this.data_size = convertToInteger(IOView8.subarray(data_start+4,data_start+8));
n@482:         
n@482:         this.num_samples = this.data_size / this.block_align;
n@482:         
n@482:         this.decoded_data = [];
n@482:         if (this.type != 1 && this.type != 3) {
n@482:             console.log("Neither PCM nor IEEE float, cannot decode");
n@482:             return 1;
n@482:         }
n@482:         for (var c=0; c<this.num_channels; c++)
n@482:         {
n@482:             this.decoded_data.push(new Float32Array(this.num_samples));
n@482:         }
n@482:         var sampleDataOffset = data_start+8;
n@482:         
n@482:         // Now need to decode the data from sampleDataOffset
n@482:         // Data is always interleved
n@482:         var data_view;
n@482:         if (this.type == 3)
n@482:         {
n@482:             // Already in float
n@482:             if (this.bits_per_sample == 32) {
n@482:                 data_view = new Float32Array(IOArrayBuffer.slice(sampleDataOffset,sampleDataOffset+this.data_size));
n@482:             } else if (this.bits_per_sample == 64) {
n@482:                 data_view = new Float64Array(IOArrayBuffer.slice(sampleDataOffset,sampleDataOffset+this.data_size));
n@482:             }
n@482:         } else if (this.type == 1)
n@482:         {
n@486:             data_view = new Float32Array(this.num_samples*this.num_channels);
n@482:             integerConvert(new Uint8Array(IOArrayBuffer.slice(sampleDataOffset,sampleDataOffset+this.data_size)),data_view,this.bits_per_sample/8);
n@482:         }
n@482:         deInterlace(data_view,this.decoded_data);
n@482:         return 0;
n@482:     };
n@482: }
n@482: 
n@482: function deInterlace(src_array, dst_array)
n@482: {
n@482:     var number = src_array.length;
n@482:     var channels = dst_array.length;
n@482:     var channel_index = 0;
n@482:     var dst_index = 0;
n@482:     for (var n=0; n<number; n++)
n@482:     {
n@482:         dst_array[channel_index][dst_index] = src_array[n];
n@482:         channel_index++;
n@482:         if (channel_index >= channels) {
n@482:             channel_index = 0;
n@482:             dst_index++;
n@482:         }
n@482:     }
n@482: }
n@482: 
n@482: function integerConvert(srcView,dstView,srcBytes)
n@482: {
n@482:     //Convert integers of a Uint8Array of certain byte length into a Float32Array
n@482:     var number = dstView.length;
n@482:     var outBits = srcBytes*8;
n@482:     var endShift = 32 - outBits;
n@482:     if (srcView.length != dstView.length*srcBytes)
n@482:     {
n@482:         return -1;
n@482:     }
n@482:     for (var n=0; n<number; n++)
n@482:     {
n@482:         var srcIndex = n*srcBytes;
n@515:         var intData = convertToInteger(srcView.subarray(srcIndex,srcIndex+srcBytes));
n@482:         intData = (intData << (endShift));
n@482:         dstView[n] = intData / 2147483648;
n@482:     }
n@482: }