Package stdlib

Class StdAudio

java.lang.Object

stdlib.StdAudio

public final class StdAudio
extends Object

Standard audio. This class provides a basic capability for creating, reading, and saving audio.

The audio format uses a sampling rate of 44,100 Hz, 16-bit, monaural.

For additional documentation, see Section 1.5 of Computer Science: An Interdisciplinary Approach by Robert Sedgewick and Kevin Wayne.

Author:

Robert Sedgewick, Kevin Wayne

Field Summary

Fields

Modifier and Type	Field	Description
private static final boolean	BIG_ENDIAN
private static final int	BITS_PER_SAMPLE
private static byte[]	buffer
private static int	bufferSize
private static final int	BYTES_PER_SAMPLE
private static SourceDataLine	line
private static final boolean	LITTLE_ENDIAN
private static final int	MAX_16_BIT
private static final int	MONO
private static final int	SAMPLE_BUFFER_SIZE
static final int	SAMPLE_RATE	The sample rate: 44,100 Hz for CD quality audio.
private static final boolean	SIGNED
private static final int	STEREO
private static final boolean	UNSIGNED

Constructor Summary

Constructors

Modifier	Constructor	Description
private	StdAudio()

Method Summary

Modifier and Type	Method	Description
static void	close()	Closes standard audio.
private static AudioInputStream	getAudioInputStreamFromFile(String filename)
private static void	init()
static void	loop(String filename)	Deprecated. replaced by loopInBackground(String filename)
static void	loopInBackground(String filename)	Loops an audio file (in .wav, .mid, or .au format) in a background thread.
static void	main(String[] args)	Test client - play an A major scale to standard audio.
private static double[]	note(double hz, double duration, double amplitude)	Unit tests StdAudio.
static void	play(double sample)	Writes one sample (between -1.0 and +1.0) to standard audio.
static void	play(double[] samples)	Writes the array of samples (between -1.0 and +1.0) to standard audio.
static void	play(String filename)	Deprecated. replaced by playInBackground(String filename)
static void	playInBackground(String filename)	Plays an audio file (in .wav, .mid, or .au format) in a background thread.
static double[]	read(String filename)	Reads audio samples from a file (in .wav or .au format) and returns them as a double array with values between -1.0 and +1.0.
static void	save(String filename, double[] samples)	Saves the double array as an audio file (using .wav or .au format).
private static void	stream(AudioInputStream ais)

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Details

SAMPLE_RATE

public static final int SAMPLE_RATE

The sample rate: 44,100 Hz for CD quality audio.

See Also:

• Constant Field Values

BYTES_PER_SAMPLE

private static final int BYTES_PER_SAMPLE

See Also:

• Constant Field Values

BITS_PER_SAMPLE

private static final int BITS_PER_SAMPLE

See Also:

• Constant Field Values

MAX_16_BIT

private static final int MAX_16_BIT

See Also:

• Constant Field Values

SAMPLE_BUFFER_SIZE

private static final int SAMPLE_BUFFER_SIZE

See Also:

• Constant Field Values

MONO

private static final int MONO

See Also:

• Constant Field Values

STEREO

private static final int STEREO

See Also:

• Constant Field Values

LITTLE_ENDIAN

private static final boolean LITTLE_ENDIAN

See Also:

• Constant Field Values

BIG_ENDIAN

private static final boolean BIG_ENDIAN

See Also:

• Constant Field Values

SIGNED

private static final boolean SIGNED

See Also:

• Constant Field Values

UNSIGNED

private static final boolean UNSIGNED

See Also:

• Constant Field Values

line

private static SourceDataLine line

buffer

private static byte[] buffer

bufferSize

private static int bufferSize

Constructor Details

StdAudio

private StdAudio()

Method Details

init

private static void init()

getAudioInputStreamFromFile

private static AudioInputStream getAudioInputStreamFromFile(String filename)

close

public static void close()

Closes standard audio.

play

public static void play(double sample)

Writes one sample (between -1.0 and +1.0) to standard audio. If the sample is outside the range, it will be clipped.

Parameters:

sample - the sample to play

Throws:

IllegalArgumentException - if the sample is Double.NaN

play

public static void play(double[] samples)

Writes the array of samples (between -1.0 and +1.0) to standard audio. If a sample is outside the range, it will be clipped.

Parameters:

samples - the array of samples to play

Throws:

IllegalArgumentException - if any sample is Double.NaN

IllegalArgumentException - if samples is null

read

public static double[] read(String filename)

Reads audio samples from a file (in .wav or .au format) and returns them as a double array with values between -1.0 and +1.0. The audio file must be 16-bit with a sampling rate of 44,100. It can be mono or stereo.

Parameters:

filename - the name of the audio file

Returns:

the array of samples

save

public static void save(String filename,
 double[] samples)

Saves the double array as an audio file (using .wav or .au format).

Parameters:

filename - the name of the audio file

samples - the array of samples

Throws:

IllegalArgumentException - if unable to save filename

IllegalArgumentException - if samples is null

IllegalArgumentException - if filename is null

IllegalArgumentException - if filename extension is not .wav or .au

play

@Deprecated
public static void play(String filename)

Deprecated.

replaced by playInBackground(String filename)

Plays an audio file (in .wav, .mid, or .au format) in a background thread.

Parameters:

filename - the name of the audio file

Throws:

IllegalArgumentException - if unable to play filename

IllegalArgumentException - if filename is null

playInBackground

public static void playInBackground(String filename)

Plays an audio file (in .wav, .mid, or .au format) in a background thread.

Parameters:

filename - the name of the audio file

Throws:

IllegalArgumentException - if unable to play filename

IllegalArgumentException - if filename is null

stream

private static void stream(AudioInputStream ais)

loop

@Deprecated
public static void loop(String filename)

Deprecated.

replaced by loopInBackground(String filename)

Loops an audio file (in .wav, .mid, or .au format) in a background thread.

Parameters:

filename - the name of the audio file

Throws:

IllegalArgumentException - if filename is null

loopInBackground

public static void loopInBackground(String filename)

Loops an audio file (in .wav, .mid, or .au format) in a background thread.

Parameters:

filename - the name of the audio file

Throws:

IllegalArgumentException - if filename is null

note

private static double[] note(double hz,
 double duration,
 double amplitude)

Unit tests StdAudio.

main

public static void main(String[] args)

Test client - play an A major scale to standard audio.

Parameters:

args - the command-line arguments