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     *
     * @param {Number} a
     *     The window size to use for the Lanczos kernel.
     *
     * @returns {number}
     *     The value of the Lanczos kernel at the given point for the given
     *     window size.
     */
    var lanczos = function lanczos(x, a) {

        // Lanczos is sinc(x) * sinc(x / a) for -a < x < a ...
        if (-a < x && x < a)
            return sinc(x) * sinc(x / a);

        // ... and 0 otherwise
        return 0;

    };

    /**
     * Determines the value of the waveform represented by the audio data at
     * the given location. If the value cannot be determined exactly as it does
     * not correspond to an exact sample within the audio data, the value will
     * be derived through interpolating nearby samples.
     *
     * @private
     * @param {Float32Array} audioData
     *     An array of audio data, as returned by AudioBuffer.getChannelData().
     *
     * @param {Number} t
     *     The relative location within the waveform from which the value
     *     should be retrieved, represented as a floating point number between
     *     0 and 1 inclusive, where 0 represents the earliest point in time and
     *     1 represents the latest.
     *
     * @returns {number}
     *     The value of the waveform at the given location.
     */
    var interpolateSample = function getValueAt(audioData, t) {

        // Convert [0, 1] range to [0, audioData.length - 1]
        var index = (audioData.length - 1) * t;

        // Determine the start and end points for the summation used by the
        // Lanczos interpolation algorithm (see: https://en.wikipedia.org/wiki/Lanczos_resampling)
        var start = Math.floor(index) - LANCZOS_WINDOW_SIZE + 1;
        var end = Math.floor(index) + LANCZOS_WINDOW_SIZE;

        // Calculate the value of the Lanczos interpolation function for the
        // required range
        var sum = 0;
        for (var i = start; i <= end; i++) {
            sum += (audioData[i] || 0) * lanczos(index - i, LANCZOS_WINDOW_SIZE);
        }

        return sum;

    };

    /**
     * Converts the given AudioBuffer into an audio packet, ready for streaming
     * along the underlying output stream. Unlike the raw audio packets used by
     * this audio recorder, AudioBuffers require floating point samples and are
     * split into isolated planes of channel-specific data.
     *
     * @private
     * @param {AudioBuffer} audioBuffer
     *     The Web Audio API AudioBuffer that should be converted to a raw
     *     audio packet.
     *
     * @returns {!SampleArray}
     *     A new raw audio packet containing the audio data from the provided
     *     AudioBuffer.
     */
    var toSampleArray = function toSampleArray(audioBuffer) {

        // Track overall amount of data read
        var inSamples = audioBuffer.length;
        readSamples += inSamples;

        // Calculate the total number of samples that should be written as of
        // the audio data just received and adjust the size of the output
        // packet accordingly
        var expectedWrittenSamples = Math.round(readSamples * format.rate / audioBuffer.sampleRate);
        var outSamples = expectedWrittenSamples - writtenSamples;

        // Update number of samples written
        writtenSamples += outSamples;

        // Get array for raw PCM storage
        var data = new SampleArray(outSamples * format.channels);

        // Convert each channel
        for (var channel = 0; channel < format.channels; channel++) {

            var audioData = audioBuffer.getChannelData(channel);

            // Fill array with data from audio buffer channel
            var offset = channel;
            for (var i = 0; i < outSamples; i++) {
                data[offset] = interpolateSample(audioData, i / (outSamples - 1)) * maxSampleValue;
                offset += format.channels;
            }

        }

        return data;

    };

    /**
     * getUserMedia() callback which handles successful retrieval of an
     * audio stream (successful start of recording).
     *
     * @private
     * @param {MediaStream} stream
     *     A MediaStream which provides access to audio data read from the
     *     user's local audio input device.
     */
    var streamReceived = function streamReceived(stream) {