view js/WAVE.js @ 2376:c41caaa96633

Some fixes for #90. Also a failsafe loop if the server never responds with meaningul information from saves (for instance, running only on apache or basic http servers). More changes to pythonServer for python 3.5. Please check if still valid on 2.7

// 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;
    }
}