diff WAVE.js @ 1088:3705f68a38b7

The version I use and works, addresses issues #1622, #1616, partially #1620

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/WAVE.js	Mon Feb 22 04:17:19 2016 +0000
@@ -0,0 +1,155 @@
+// Decode and perform WAVE file byte level manipulation
+
+find_subarray = function(arr,subarr) {
+    var arr_length = arr.length;
+    var subarr_length = subarr.length;
+    var last_check_index = arr_length - subarr_length;
+    
+    positionLoop:
+    for (var i=0; i <= last_check_index; i++)
+    {
+        for (var j=0; j< subarr_length; j++)
+        {
+            if (arr[i + j] !== subarr[j]) {
+                continue positionLoop;
+            }
+        }
+        return i;
+    }
+    return -1;
+};
+
+function convertToInteger(arr) {
+    var value = 0;
+    for (var i=0; i<arr.length; i++)
+    {
+        value += arr[i]<<(i*8);
+    }
+    return value;
+}
+function convertToString(arr) {
+    var str = "";
+    for (var i=0; i<arr.length; i++)
+    {
+        str = str.concat(String.fromCharCode(arr[i]));
+    }
+    return str;
+}
+
+function WAVE()
+{
+    // The WAVE file object
+    this.status == 'WAVE_DECLARED'
+    
+    this.decoded_data = null;
+    
+    this.RIFF = String(); //ChunkID
+	this.size; //ChunkSize
+	this.FT_Header; //Format
+	this.fmt_marker; //Subchunk1ID
+	this.formatDataLength; //Subchunk1Size
+	this.type; //AudioFormat
+	this.num_channels; //NumChannels
+	this.sample_rate; //SampleRate
+	this.byte_rate; //ByteRate
+	this.block_align; //BlockAlign
+	this.bits_per_sample; //BitsPerSample
+	this.data_header; //Subchunk2ID
+	this.data_size; //Subchunk2Size
+    this.num_samples;
+    
+    this.open = function(IOArrayBuffer)
+    {
+        var IOView8 = new Uint8Array(IOArrayBuffer);
+        this.RIFF = convertToString(IOView8.subarray(0,4));
+        if (this.RIFF != 'RIFF')
+        {
+            console.log('WAVE ERR - Not a RIFF file');
+            return 1;
+        }
+        this.size = convertToInteger(IOView8.subarray(4,8));
+        this.FT_Header = convertToString(IOView8.subarray(8,12));
+        this.fmt_marker = convertToString(IOView8.subarray(12,16));
+        this.formatDataLength = convertToInteger(IOView8.subarray(16,20));
+        this.type = convertToInteger(IOView8.subarray(20,22));
+        this.num_channels = convertToInteger(IOView8.subarray(22,24));
+        this.sample_rate = convertToInteger(IOView8.subarray(24,28));
+        this.byte_rate = convertToInteger(IOView8.subarray(28,32));
+        this.block_align = convertToInteger(IOView8.subarray(32,34));
+        this.bits_per_sample = convertToInteger(IOView8.subarray(34,36));
+        
+        // Find the data header first
+        var data_start = find_subarray(IOView8,[100, 97, 116, 97]);
+        
+        this.data_header = convertToString(IOView8.subarray(data_start,data_start+4));
+        this.data_size = convertToInteger(IOView8.subarray(data_start+4,data_start+8));
+        
+        this.num_samples = this.data_size / this.block_align;
+        
+        this.decoded_data = [];
+        if (this.type != 1 && this.type != 3) {
+            console.log("Neither PCM nor IEEE float, cannot decode");
+            return 1;
+        }
+        for (var c=0; c<this.num_channels; c++)
+        {
+            this.decoded_data.push(new Float32Array(this.num_samples));
+        }
+        var sampleDataOffset = data_start+8;
+        
+        // Now need to decode the data from sampleDataOffset
+        // Data is always interleved
+        var data_view;
+        if (this.type == 3)
+        {
+            // Already in float
+            if (this.bits_per_sample == 32) {
+                data_view = new Float32Array(IOArrayBuffer.slice(sampleDataOffset,sampleDataOffset+this.data_size));
+            } else if (this.bits_per_sample == 64) {
+                data_view = new Float64Array(IOArrayBuffer.slice(sampleDataOffset,sampleDataOffset+this.data_size));
+            }
+        } else if (this.type == 1)
+        {
+            data_view = new Float32Array(this.num_samples*this.num_channels);
+            integerConvert(new Uint8Array(IOArrayBuffer.slice(sampleDataOffset,sampleDataOffset+this.data_size)),data_view,this.bits_per_sample/8);
+        }
+        deInterlace(data_view,this.decoded_data);
+        return 0;
+    };
+}
+
+function deInterlace(src_array, dst_array)
+{
+    var number = src_array.length;
+    var channels = dst_array.length;
+    var channel_index = 0;
+    var dst_index = 0;
+    for (var n=0; n<number; n++)
+    {
+        dst_array[channel_index][dst_index] = src_array[n];
+        channel_index++;
+        if (channel_index >= channels) {
+            channel_index = 0;
+            dst_index++;
+        }
+    }
+}
+
+function integerConvert(srcView,dstView,srcBytes)
+{
+    //Convert integers of a Uint8Array of certain byte length into a Float32Array
+    var number = dstView.length;
+    var outBits = srcBytes*8;
+    var endShift = 32 - outBits;
+    if (srcView.length != dstView.length*srcBytes)
+    {
+        return -1;
+    }
+    for (var n=0; n<number; n++)
+    {
+        var srcIndex = n*srcBytes;
+        var intData = convertToInteger(srcView.subarray(srcIndex,srcIndex+srcBytes));
+        intData = (intData << (endShift));
+        dstView[n] = intData / 2147483648;
+    }
+}
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