me@1936: // Decode and perform WAVE file byte level manipulation
me@1936: 
me@1936: find_subarray = function(arr,subarr) {
me@1936:     var arr_length = arr.length;
me@1936:     var subarr_length = subarr.length;
me@1936:     var last_check_index = arr_length - subarr_length;
me@1936:     
me@1936:     positionLoop:
me@1936:     for (var i=0; i <= last_check_index; i++)
me@1936:     {
me@1936:         for (var j=0; j< subarr_length; j++)
me@1936:         {
me@1936:             if (arr[i + j] !== subarr[j]) {
me@1936:                 continue positionLoop;
me@1936:             }
me@1936:         }
me@1936:         return i;
me@1936:     }
me@1936:     return -1;
me@1936: };
me@1936: 
me@1936: function convertToInteger(arr) {
me@1936:     var value = 0;
me@1936:     for (var i=0; i<arr.length; i++)
me@1936:     {
me@1936:         value += arr[i]<<(i*8);
me@1936:     }
me@1936:     return value;
me@1936: }
me@1936: function convertToString(arr) {
me@1936:     var str = "";
me@1936:     for (var i=0; i<arr.length; i++)
me@1936:     {
me@1936:         str = str.concat(String.fromCharCode(arr[i]));
me@1936:     }
me@1936:     return str;
me@1936: }
me@1936: 
me@1936: function WAVE()
me@1936: {
me@1936:     // The WAVE file object
me@1936:     this.status == 'WAVE_DECLARED'
me@1936:     
me@1936:     this.decoded_data = null;
me@1936:     
me@1936:     this.RIFF = String(); //ChunkID
me@1936: 	this.size; //ChunkSize
me@1936: 	this.FT_Header; //Format
me@1936: 	this.fmt_marker; //Subchunk1ID
me@1936: 	this.formatDataLength; //Subchunk1Size
me@1936: 	this.type; //AudioFormat
me@1936: 	this.num_channels; //NumChannels
me@1936: 	this.sample_rate; //SampleRate
me@1936: 	this.byte_rate; //ByteRate
me@1936: 	this.block_align; //BlockAlign
me@1936: 	this.bits_per_sample; //BitsPerSample
me@1936: 	this.data_header; //Subchunk2ID
me@1936: 	this.data_size; //Subchunk2Size
me@1936:     this.num_samples;
me@1936:     
me@1936:     this.open = function(IOArrayBuffer)
me@1936:     {
me@1936:         var IOView8 = new Uint8Array(IOArrayBuffer);
me@1936:         this.RIFF = convertToString(IOView8.subarray(0,4));
me@1936:         if (this.RIFF != 'RIFF')
me@1936:         {
me@1936:             console.log('WAVE ERR - Not a RIFF file');
me@1936:             return 1;
me@1936:         }
me@1936:         this.size = convertToInteger(IOView8.subarray(4,8));
me@1936:         this.FT_Header = convertToString(IOView8.subarray(8,12));
me@1936:         this.fmt_marker = convertToString(IOView8.subarray(12,16));
me@1936:         this.formatDataLength = convertToInteger(IOView8.subarray(16,20));
me@1936:         this.type = convertToInteger(IOView8.subarray(20,22));
me@1936:         this.num_channels = convertToInteger(IOView8.subarray(22,24));
me@1936:         this.sample_rate = convertToInteger(IOView8.subarray(24,28));
me@1936:         this.byte_rate = convertToInteger(IOView8.subarray(28,32));
me@1936:         this.block_align = convertToInteger(IOView8.subarray(32,34));
me@1936:         this.bits_per_sample = convertToInteger(IOView8.subarray(34,36));
me@1936:         
me@1936:         // Find the data header first
me@1936:         var data_start = find_subarray(IOView8,[100, 97, 116, 97]);
me@1936:         
me@1936:         this.data_header = convertToString(IOView8.subarray(data_start,data_start+4));
me@1936:         this.data_size = convertToInteger(IOView8.subarray(data_start+4,data_start+8));
me@1936:         
me@1936:         this.num_samples = this.data_size / this.block_align;
me@1936:         
me@1936:         this.decoded_data = [];
me@1936:         if (this.type != 1 && this.type != 3) {
me@1936:             console.log("Neither PCM nor IEEE float, cannot decode");
me@1936:             return 1;
me@1936:         }
me@1936:         for (var c=0; c<this.num_channels; c++)
me@1936:         {
me@1936:             this.decoded_data.push(new Float32Array(this.num_samples));
me@1936:         }
me@1936:         var sampleDataOffset = data_start+8;
me@1936:         
me@1936:         // Now need to decode the data from sampleDataOffset
me@1936:         // Data is always interleved
me@1936:         var data_view;
me@1936:         if (this.type == 3)
me@1936:         {
me@1936:             // Already in float
me@1936:             if (this.bits_per_sample == 32) {
me@1936:                 data_view = new Float32Array(IOArrayBuffer.slice(sampleDataOffset,sampleDataOffset+this.data_size));
me@1936:             } else if (this.bits_per_sample == 64) {
me@1936:                 data_view = new Float64Array(IOArrayBuffer.slice(sampleDataOffset,sampleDataOffset+this.data_size));
me@1936:             }
me@1936:         } else if (this.type == 1)
me@1936:         {
me@1936:             data_view = new Float32Array(this.num_samples*this.num_channels);
me@1936:             integerConvert(new Uint8Array(IOArrayBuffer.slice(sampleDataOffset,sampleDataOffset+this.data_size)),data_view,this.bits_per_sample/8);
me@1936:         }
me@1936:         deInterlace(data_view,this.decoded_data);
me@1936:         return 0;
me@1936:     };
me@1936: }
me@1936: 
me@1936: function deInterlace(src_array, dst_array)
me@1936: {
me@1936:     var number = src_array.length;
me@1936:     var channels = dst_array.length;
me@1936:     var channel_index = 0;
me@1936:     var dst_index = 0;
me@1936:     for (var n=0; n<number; n++)
me@1936:     {
me@1936:         dst_array[channel_index][dst_index] = src_array[n];
me@1936:         channel_index++;
me@1936:         if (channel_index >= channels) {
me@1936:             channel_index = 0;
me@1936:             dst_index++;
me@1936:         }
me@1936:     }
me@1936: }
me@1936: 
me@1936: function integerConvert(srcView,dstView,srcBytes)
me@1936: {
me@1936:     //Convert integers of a Uint8Array of certain byte length into a Float32Array
me@1936:     var number = dstView.length;
me@1936:     var outBits = srcBytes*8;
me@1936:     var endShift = 32 - outBits;
me@1936:     if (srcView.length != dstView.length*srcBytes)
me@1936:     {
me@1936:         return -1;
me@1936:     }
me@1936:     for (var n=0; n<number; n++)
me@1936:     {
me@1936:         var srcIndex = n*srcBytes;
me@1936:         var intData = convertToInteger(srcView.subarray(srcIndex,srcIndex+srcBytes));
me@1936:         intData = (intData << (endShift));
me@1936:         dstView[n] = intData / 2147483648;
me@1936:     }
me@1936: }