Manipulating Sound

CS1316: Representing Structure and Behavior

Story

Programming Sampled Sounds in Java• Manipulating sounds in-place

• Returning a new sound

Manipulating an array• Inserting a sound

• Deleting a sound segment

Loading and playing sounds

Welcome to DrJava.

> Sound s = new Sound(“C:/cs1316/MediaSources/thisisatest.wav")

> s.increaseVolume(2.0);

> s.play();

increaseVolume method

/** * Increase the volume of a sound **/ public void increaseVolume(double factor){ SoundSample [] samples = this.getSamples(); SoundSample current = null; for (int i=0; i < samples.length; i++) { current = samples[i]; current.setValue((int) (factor * current.getValue())); } }

increaseVolume: How it works

SoundSample is the name of the class for samples.• There’s something named Sample already in Java, so

it would get confusing.

getSamples(), getValue(), and setValue() work just the same as in CS1315 Python.• They (respectively) return an array of all the samples,

get the value of a given sample object, and set the value of a given sample object.

Methods that return sounds

> Sound s = new Sound("D:/cs1316/MediaSources/thisisatest.wav")

> s.play()

> s.reverse()

Sound number of samples: 64513

Why do you think we’re seeing this?

Reverse returns a Sound! /** * Method to reverse a sound. **/ public Sound reverse() { Sound target = new Sound(getLength()); int sampleValue; for (int srcIndex=0,trgIndex=getLength()-1; srcIndex < getLength(); srcIndex++,trgIndex--) { sampleValue = this.getSampleValueAt(srcIndex); target.setSampleValueAt(trgIndex,sampleValue); }; return target; }

Methods that cascade nicely in Sound

public Sound reverse() public Sound append(Sound

appendSound) public Sound mix(Sound mixIn, double

ratio) public Sound scale(double factor)

Little sounds in MediaSources

-h: Half second

-q: Quarter second

-1 or -2: 1 or 2 seconds

-tenth: 1/10 second

-twentieth: 1/20 second

Making collages

public class MySoundCollage { public static void main(String [] args){ Sound snap = new

Sound(FileChooser.getMediaPath("snap-tenth.wav")); Sound drum = new

Sound(FileChooser.getMediaPath("drumroll-1.wav")); Sound clink = new

Sound(FileChooser.getMediaPath("clink-tenth.wav")); Sound clap = new

Sound(FileChooser.getMediaPath("clap-q.wav")); Sound drumRev = drum.reverse().scale(0.5); Sound soundA =

snap.append(clink).append(clink).append(clap).append(drumRev);

Sound soundB = clink.append(clap).append(clap).append(drum).append(snap).append(snap);

Sound collage =

soundA.append(soundB).append(soundB).append(soundA).append(soundA).append(soundB);

collage.play(); }}

How do we insert and delete sound?

Welcome to DrJava.> Sound test = new

Sound("D:/cs1316/MediaSources/thisisatest.wav");> test.getLength()64513> Sound clink = new Sound("D:/cs1316/MediaSources/clink-

tenth.wav");> clink.getLength()2184> test.insertAfter(clink,40000)> test.play()

Handling the error cases

> Sound test2 = new Sound("D:/cs1316/MediaSources/thisisatest.wav");

> test.insertAfter(test2,40000)

> test.play()

First, making room0 1 2 3 start this.getLength()

12 94 11-27-152

inSound.getLength()

0 1 2 3 start start+inSound.getLength()

12 94

…

Second, copying in

inSound.getLength()

0 1 2 3 start start+inSound.getLength()

12 94

…

insertAftermethod

/** * insert the input Sound after the nth sample (input integer). * Modifies the given sound * @param insound Sound to insert * @param start index where to start inserting the new sound **/ public void insertAfter(Sound inSound, int start){ SoundSample current=null; // Find how long insound is int amtToCopy = inSound.getLength(); int endOfThis = this.getLength()-1; if (start + amtToCopy > endOfThis) {// If too long, copy only as much as will fit amtToCopy = endOfThis-start-1;} else { // If short enough, need to clear out room. // Copy from endOfThis-amtToCopy;, moving backwards // (toward front of list) to start, // moving UP (toward back) to endOfThis // KEY INSIGHT: How much gets lost off the end of the // array? Same size as what we're inserting -- amtToCopy for (int source=endOfThis-amtToCopy; source >= start ; source--) { // current is the TARGET -- where we're copying to current = this.getSample(source+amtToCopy); current.setValue(this.getSampleValueAt(source)); } } // NOW, copy in inSound up to amtToCopy for (int target=start,source=0; source < amtToCopy; target++, source++) { current = this.getSample(target); current.setValue(inSound.getSampleValueAt(source)); } }

Setting up the variables

SoundSample current=null;

// Find how long insound is

int amtToCopy = inSound.getLength();

int endOfThis = this.getLength()-1;

Checking for room

if (start + amtToCopy > endOfThis) {// If too long, copy only as much as will fit amtToCopy = endOfThis-start-1;} else { // If short enough, need to clear out room.

Now, copy down else { // If short enough, need to clear out room. // Copy from endOfThis-amtToCopy;, moving backwards // (toward front of list) to start, // moving UP (toward back) to endOfThis // KEY INSIGHT: How much gets lost off the end of the // array? Same size as what we're inserting -- amtToCopy for (int source=endOfThis-amtToCopy; source >= start ; source--) { // current is the TARGET -- where we're copying to current = this.getSample(source+amtToCopy); current.setValue(this.getSampleValueAt(source)); } }

Finally, copy in the new sound

//** Second, copy in inSound up to amtToCopy

for (int target=start,source=0;

source < amtToCopy;

target++, source++) {

current = this.getSample(target);

current.setValue(

inSound.getSampleValueAt(source));

}

How do we delete?

> Sound test = new Sound("D:/cs1316/MediaSources/thisisatest.wav");

> test.getLength()

64513

> test.delete(2000,30000)

> test.play() // We hear “This test”

First, copy from end to getLength, back to start

this.getLength()endstart

This distance is start-end

Then, clear out the end

this.getLength()endstart

00000000…

This distance is start-end.

And we’ll go from the length, backwards.

Deleting method

/** * Delete from start to end in this sound * @param start where to start deletion * @param end where to stop deletion **/ public void delete(int start, int end){ int value = 0; // Basically, we simply copy from "end" to

getLength back to start for (int source=end, target=start; source < this.getLength(); source++, target++) {value = this.getSampleValueAt(source); this.setSampleValueAt(target,value);} // Then clear out the rest. Gap is end-start

length int gap = end-start; for (int i=1; i <= gap ; i++) { this.setSampleValueAt(this.getLength()-i,0);} }

First, copy up—over the start to end gap

// Basically, we simply copy from "end" to getLength back to start

for (int source=end, target=start;

source < this.getLength();

source++, target++)

{value = this.getSampleValueAt(source);

this.setSampleValueAt(target,value);}

Then, clear out the gap at the end

// Then clear out the rest. Gap is end-start length

int gap = end-start;

for (int i=1; i <= gap ; i++) {

this.setSampleValueAt(

this.getLength()-i, 0);}

Arrays: Strengths and weaknesses

Strengths:• Easy to understand

• Very efficient

• “Static”—it’s always the same length (shape?)

Weaknesses:• Any change in the middle is hard to do

• Expensive in complexity and processing

• “Static”—it’s always the same length (shape?)