nicholas@2224: // Decode and perform WAVE file byte level manipulation
nicholas@2224: 
nicholas@2224: find_subarray = function(arr,subarr) {
nicholas@2224:     var arr_length = arr.length;
nicholas@2224:     var subarr_length = subarr.length;
nicholas@2224:     var last_check_index = arr_length - subarr_length;
nicholas@2224:     
nicholas@2224:     positionLoop:
nicholas@2224:     for (var i=0; i <= last_check_index; i++)
nicholas@2224:     {
nicholas@2224:         for (var j=0; j< subarr_length; j++)
nicholas@2224:         {
nicholas@2224:             if (arr[i + j] !== subarr[j]) {
nicholas@2224:                 continue positionLoop;
nicholas@2224:             }
nicholas@2224:         }
nicholas@2224:         return i;
nicholas@2224:     }
nicholas@2224:     return -1;
nicholas@2224: };
nicholas@2224: 
nicholas@2224: function convertToInteger(arr) {
nicholas@2224:     var value = 0;
nicholas@2224:     for (var i=0; i<arr.length; i++)
nicholas@2224:     {
nicholas@2224:         value += arr[i]<<(i*8);
nicholas@2224:     }
nicholas@2224:     return value;
nicholas@2224: }
nicholas@2224: function convertToString(arr) {
nicholas@2224:     var str = "";
nicholas@2224:     for (var i=0; i<arr.length; i++)
nicholas@2224:     {
nicholas@2224:         str = str.concat(String.fromCharCode(arr[i]));
nicholas@2224:     }
nicholas@2224:     return str;
nicholas@2224: }
nicholas@2224: 
nicholas@2224: function WAVE()
nicholas@2224: {
nicholas@2224:     // The WAVE file object
nicholas@2224:     this.status == 'WAVE_DECLARED'
nicholas@2224:     
nicholas@2224:     this.decoded_data = null;
nicholas@2224:     
nicholas@2224:     this.RIFF = String(); //ChunkID
nicholas@2224: 	this.size; //ChunkSize
nicholas@2224: 	this.FT_Header; //Format
nicholas@2224: 	this.fmt_marker; //Subchunk1ID
nicholas@2224: 	this.formatDataLength; //Subchunk1Size
nicholas@2224: 	this.type; //AudioFormat
nicholas@2224: 	this.num_channels; //NumChannels
nicholas@2224: 	this.sample_rate; //SampleRate
nicholas@2224: 	this.byte_rate; //ByteRate
nicholas@2224: 	this.block_align; //BlockAlign
nicholas@2224: 	this.bits_per_sample; //BitsPerSample
nicholas@2224: 	this.data_header; //Subchunk2ID
nicholas@2224: 	this.data_size; //Subchunk2Size
nicholas@2224:     this.num_samples;
nicholas@2224:     
nicholas@2224:     this.open = function(IOArrayBuffer)
nicholas@2224:     {
nicholas@2224:         var IOView8 = new Uint8Array(IOArrayBuffer);
nicholas@2224:         this.RIFF = convertToString(IOView8.subarray(0,4));
nicholas@2224:         if (this.RIFF != 'RIFF')
nicholas@2224:         {
nicholas@2224:             console.log('WAVE ERR - Not a RIFF file');
nicholas@2224:             return 1;
nicholas@2224:         }
nicholas@2224:         this.size = convertToInteger(IOView8.subarray(4,8));
nicholas@2224:         this.FT_Header = convertToString(IOView8.subarray(8,12));
nicholas@2224:         this.fmt_marker = convertToString(IOView8.subarray(12,16));
nicholas@2224:         this.formatDataLength = convertToInteger(IOView8.subarray(16,20));
nicholas@2224:         this.type = convertToInteger(IOView8.subarray(20,22));
nicholas@2224:         this.num_channels = convertToInteger(IOView8.subarray(22,24));
nicholas@2224:         this.sample_rate = convertToInteger(IOView8.subarray(24,28));
nicholas@2224:         this.byte_rate = convertToInteger(IOView8.subarray(28,32));
nicholas@2224:         this.block_align = convertToInteger(IOView8.subarray(32,34));
nicholas@2224:         this.bits_per_sample = convertToInteger(IOView8.subarray(34,36));
nicholas@2224:         
nicholas@2224:         // Find the data header first
nicholas@2224:         var data_start = find_subarray(IOView8,[100, 97, 116, 97]);
nicholas@2224:         
nicholas@2224:         this.data_header = convertToString(IOView8.subarray(data_start,data_start+4));
nicholas@2224:         this.data_size = convertToInteger(IOView8.subarray(data_start+4,data_start+8));
nicholas@2224:         
nicholas@2224:         this.num_samples = this.data_size / this.block_align;
nicholas@2224:         
nicholas@2224:         this.decoded_data = [];
nicholas@2224:         if (this.type != 1 && this.type != 3) {
nicholas@2224:             console.log("Neither PCM nor IEEE float, cannot decode");
nicholas@2224:             return 1;
nicholas@2224:         }
nicholas@2224:         for (var c=0; c<this.num_channels; c++)
nicholas@2224:         {
nicholas@2224:             this.decoded_data.push(new Float32Array(this.num_samples));
nicholas@2224:         }
nicholas@2224:         var sampleDataOffset = data_start+8;
nicholas@2224:         
nicholas@2224:         // Now need to decode the data from sampleDataOffset
nicholas@2224:         // Data is always interleved
nicholas@2224:         var data_view;
nicholas@2224:         if (this.type == 3)
nicholas@2224:         {
nicholas@2224:             // Already in float
nicholas@2224:             if (this.bits_per_sample == 32) {
nicholas@2224:                 data_view = new Float32Array(IOArrayBuffer.slice(sampleDataOffset,sampleDataOffset+this.data_size));
nicholas@2224:             } else if (this.bits_per_sample == 64) {
nicholas@2224:                 data_view = new Float64Array(IOArrayBuffer.slice(sampleDataOffset,sampleDataOffset+this.data_size));
nicholas@2224:             }
nicholas@2224:         } else if (this.type == 1)
nicholas@2224:         {
nicholas@2224:             data_view = new Float32Array(this.num_samples*this.num_channels);
nicholas@2224:             integerConvert(new Uint8Array(IOArrayBuffer.slice(sampleDataOffset,sampleDataOffset+this.data_size)),data_view,this.bits_per_sample/8);
nicholas@2224:         }
nicholas@2224:         deInterlace(data_view,this.decoded_data);
nicholas@2224:         return 0;
nicholas@2224:     };
nicholas@2224: }
nicholas@2224: 
nicholas@2224: function deInterlace(src_array, dst_array)
nicholas@2224: {
nicholas@2224:     var number = src_array.length;
nicholas@2224:     var channels = dst_array.length;
nicholas@2224:     var channel_index = 0;
nicholas@2224:     var dst_index = 0;
nicholas@2224:     for (var n=0; n<number; n++)
nicholas@2224:     {
nicholas@2224:         dst_array[channel_index][dst_index] = src_array[n];
nicholas@2224:         channel_index++;
nicholas@2224:         if (channel_index >= channels) {
nicholas@2224:             channel_index = 0;
nicholas@2224:             dst_index++;
nicholas@2224:         }
nicholas@2224:     }
nicholas@2224: }
nicholas@2224: 
nicholas@2224: function integerConvert(srcView,dstView,srcBytes)
nicholas@2224: {
nicholas@2224:     //Convert integers of a Uint8Array of certain byte length into a Float32Array
nicholas@2224:     var number = dstView.length;
nicholas@2224:     var outBits = srcBytes*8;
nicholas@2224:     var endShift = 32 - outBits;
nicholas@2224:     if (srcView.length != dstView.length*srcBytes)
nicholas@2224:     {
nicholas@2224:         return -1;
nicholas@2224:     }
nicholas@2224:     for (var n=0; n<number; n++)
nicholas@2224:     {
nicholas@2224:         var srcIndex = n*srcBytes;
nicholas@2224:         var intData = convertToInteger(srcView.subarray(srcIndex,srcIndex+srcBytes));
nicholas@2224:         intData = (intData << (endShift));
nicholas@2224:         dstView[n] = intData / 2147483648;
nicholas@2224:     }
nicholas@2224: }