nicholas@2224: // Decode and perform WAVE file byte level manipulation
nicholas@2683: /*globals console, Uint8Array, Float32Array, Float64Array */
nicholas@2224: 
nicholas@2683: function find_subarray(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@2538: 
nicholas@2224:     positionLoop:
nicholas@2538:         for (var i = 0; i <= last_check_index; i++) {
nicholas@2538:             for (var j = 0; j < subarr_length; j++) {
nicholas@2538:                 if (arr[i + j] !== subarr[j]) {
nicholas@2538:                     continue positionLoop;
nicholas@2538:                 }
nicholas@2224:             }
nicholas@2538:             return i;
nicholas@2224:         }
nicholas@2224:     return -1;
nicholas@2683: }
nicholas@2224: 
nicholas@2224: function convertToInteger(arr) {
nicholas@2224:     var value = 0;
nicholas@2538:     for (var i = 0; i < arr.length; i++) {
nicholas@2538:         value += arr[i] << (i * 8);
nicholas@2224:     }
nicholas@2224:     return value;
nicholas@2224: }
nicholas@2538: 
nicholas@2224: function convertToString(arr) {
nicholas@2224:     var str = "";
nicholas@2538:     for (var i = 0; i < arr.length; i++) {
nicholas@2224:         str = str.concat(String.fromCharCode(arr[i]));
nicholas@2224:     }
nicholas@2224:     return str;
nicholas@2224: }
nicholas@2224: 
nicholas@2538: function WAVE() {
nicholas@2224:     // The WAVE file object
nicholas@2683:     this.status = 'WAVE_DECLARED';
nicholas@2538: 
nicholas@2224:     this.decoded_data = null;
nicholas@2538: 
nicholas@2224:     this.RIFF = String(); //ChunkID
nicholas@2683:     this.size = undefined; //ChunkSize
nicholas@2683:     this.FT_Header = undefined; //Format
nicholas@2683:     this.fmt_marker = undefined; //Subchunk1ID
nicholas@2683:     this.formatDataLength = undefined; //Subchunk1Size
nicholas@2683:     this.type = undefined; //AudioFormat
nicholas@2683:     this.num_channels = undefined; //NumChannels
nicholas@2683:     this.sample_rate = undefined; //SampleRate
nicholas@2683:     this.byte_rate = undefined; //ByteRate
nicholas@2683:     this.block_align = undefined; //BlockAlign
nicholas@2683:     this.bits_per_sample = undefined; //BitsPerSample
nicholas@2683:     this.data_header = undefined; //Subchunk2ID
nicholas@2683:     this.data_size = undefined; //Subchunk2Size
nicholas@2683:     this.num_samples = undefined;
nicholas@2538: 
nicholas@2538:     this.open = function (IOArrayBuffer) {
nicholas@2224:         var IOView8 = new Uint8Array(IOArrayBuffer);
nicholas@2538:         this.RIFF = convertToString(IOView8.subarray(0, 4));
nicholas@2538:         if (this.RIFF != 'RIFF') {
nicholas@2224:             console.log('WAVE ERR - Not a RIFF file');
nicholas@2224:             return 1;
nicholas@2224:         }
nicholas@2538:         this.size = convertToInteger(IOView8.subarray(4, 8));
nicholas@2538:         this.FT_Header = convertToString(IOView8.subarray(8, 12));
nicholas@2538:         this.fmt_marker = convertToString(IOView8.subarray(12, 16));
nicholas@2538:         this.formatDataLength = convertToInteger(IOView8.subarray(16, 20));
nicholas@2538:         this.type = convertToInteger(IOView8.subarray(20, 22));
nicholas@2538:         this.num_channels = convertToInteger(IOView8.subarray(22, 24));
nicholas@2538:         this.sample_rate = convertToInteger(IOView8.subarray(24, 28));
nicholas@2538:         this.byte_rate = convertToInteger(IOView8.subarray(28, 32));
nicholas@2538:         this.block_align = convertToInteger(IOView8.subarray(32, 34));
nicholas@2538:         this.bits_per_sample = convertToInteger(IOView8.subarray(34, 36));
nicholas@2538: 
nicholas@2224:         // Find the data header first
nicholas@2538:         var data_start = find_subarray(IOView8, [100, 97, 116, 97]);
nicholas@2538: 
nicholas@2538:         this.data_header = convertToString(IOView8.subarray(data_start, data_start + 4));
nicholas@2538:         this.data_size = convertToInteger(IOView8.subarray(data_start + 4, data_start + 8));
nicholas@2538: 
nicholas@2224:         this.num_samples = this.data_size / this.block_align;
nicholas@2538: 
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@2538:         for (var c = 0; c < this.num_channels; c++) {
nicholas@2224:             this.decoded_data.push(new Float32Array(this.num_samples));
nicholas@2224:         }
nicholas@2538:         var sampleDataOffset = data_start + 8;
nicholas@2538: 
nicholas@2224:         // Now need to decode the data from sampleDataOffset
nicholas@2224:         // Data is always interleved
nicholas@2224:         var data_view;
nicholas@2538:         if (this.type == 3) {
nicholas@2224:             // Already in float
nicholas@2224:             if (this.bits_per_sample == 32) {
nicholas@2538:                 data_view = new Float32Array(IOArrayBuffer.slice(sampleDataOffset, sampleDataOffset + this.data_size));
nicholas@2224:             } else if (this.bits_per_sample == 64) {
nicholas@2538:                 data_view = new Float64Array(IOArrayBuffer.slice(sampleDataOffset, sampleDataOffset + this.data_size));
nicholas@2224:             }
nicholas@2538:         } else if (this.type == 1) {
nicholas@2538:             data_view = new Float32Array(this.num_samples * this.num_channels);
nicholas@2538:             integerConvert(new Uint8Array(IOArrayBuffer.slice(sampleDataOffset, sampleDataOffset + this.data_size)), data_view, this.bits_per_sample / 8);
nicholas@2224:         }
nicholas@2538:         deInterlace(data_view, this.decoded_data);
nicholas@2224:         return 0;
nicholas@2224:     };
nicholas@2224: }
nicholas@2224: 
nicholas@2538: function deInterlace(src_array, dst_array) {
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@2538:     for (var n = 0; n < number; n++) {
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@2538: function integerConvert(srcView, dstView, srcBytes) {
nicholas@2224:     //Convert integers of a Uint8Array of certain byte length into a Float32Array
nicholas@2224:     var number = dstView.length;
nicholas@2538:     var outBits = srcBytes * 8;
nicholas@2224:     var endShift = 32 - outBits;
nicholas@2538:     if (srcView.length != dstView.length * srcBytes) {
nicholas@2224:         return -1;
nicholas@2224:     }
nicholas@2538:     for (var n = 0; n < number; n++) {
nicholas@2538:         var srcIndex = n * srcBytes;
nicholas@2538:         var intData = convertToInteger(srcView.subarray(srcIndex, srcIndex + srcBytes));
nicholas@2224:         intData = (intData << (endShift));
nicholas@2224:         dstView[n] = intData / 2147483648;
nicholas@2224:     }
nicholas@2538: }