cse-101-java/AudioCollage.java at main · MahirSalahin/cse-101-java · GitHub

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/* *****************************************************************************
 *  Name:              Ada Lovelace
 *  Coursera User ID:  123456
 *  Last modified:     October 16, 1842
 **************************************************************************** */

public class AudioCollage {
    // Returns a new array that rescales a[] by a multiplicative factor of alpha.
    public static double[] amplify(double[] a, double alpha) {
        for (int i = 0; i < a.length; i++) {
            a[i] = a[i] * alpha;
        }
        return a;
    }

    // Returns a new array that is the reverse of a[].
    public static double[] reverse(double[] a) {
        double[] x = new double[a.length];
        for (int i = 0; i < a.length; i++) {
            x[i] = a[a.length - 1 - i];
        }
        return x;
    }

    // Returns a new array that is the concatenation of a[] and b[].
    public static double[] merge(double[] a, double[] b) {
        int length_a = a.length;
        int length_b = b.length;
        int l = length_a + length_b;
        double[] x = new double[l];
        int pos = 0;
        for (int i = 0; i < a.length; i++) {
            x[pos++] = a[i];
        }
        for (int i = 0; i < b.length; i++) {
            x[pos++] = b[i];
        }
        return x;
    }

    // Returns a new array that is the sum of a[] and b[],
    // padding the shorter arrays with trailing 0s if necessary.
    public static double[] mix(double[] a, double[] b) {
        int length_a = a.length;
        int length_b = b.length;
        int l = Math.max(length_a, length_b);
        double[] aa = new double[l];
        double[] bb = new double[l];
        double[] x = new double[l];
        for (int i = 0; i < length_a; i++) aa[i] = a[i];
        for (int i = 0; i < length_b; i++) bb[i] = b[i];
        for (int i = 0; i < l; i++) {
            x[i] = aa[i] + bb[i];
        }
        return x;
    }

    // Returns a new array that changes the speed by the given factor.
    public static double[] changeSpeed(double[] a, double alpha) {
        int samples_len = (int) Math.floor(a.length / alpha);
        double[] x = new double[samples_len];
        for (int i = 0; i < x.length; i++) {
            int f = (int) Math.floor(i * alpha);
            x[i] = a[f];
        }
        return x;
    }

    // Creates an audio collage and plays it on standard audio.
    public static void main(String[] args) {
        String[] wav_files = {
                "chimes.wav", "harp.wav", "scratch.wav", "silence.wav", "singer.wav"
        };
        double[] f1 = StdAudio.read(wav_files[0]);
        double[] f2 = StdAudio.read(wav_files[1]);
        double[] f3 = StdAudio.read(wav_files[2]);
        double[] f4 = StdAudio.read(wav_files[3]);
        double[] f5 = StdAudio.read(wav_files[4]);
        StdAudio.play(amplify(f1, 0.7));
        StdAudio.play(reverse(f5));
        StdAudio.play(mix(f1, f3));
        StdAudio.play(merge(f5, f4));
        StdAudio.play(changeSpeed(f2, 1.25));
    }
}