lava.riff.wave
Class WaveFormatChunk

java.lang.Object
  |
  +--lava.riff.wave.WaveFormatChunk

Direct Known Subclasses:

PcmWaveFormatChunk

public abstract class WaveFormatChunk

extends java.lang.Object

implements java.lang.Cloneable

Base format chunk.

Details: A WaveFormatChunk represents the mandatory portion of a wave format ('fmt') chunk in a RIFF-WAVE file. All RIFF-WAVE format chunks begin with the fields represented in this class, and then continue with their own, format-specific fields. The mandatory fields are (using "windows.h" notation):

struct
{
	WORD  wFormatTag;       // Format category
	WORD  wChannels;        // Number of channels
	DWORD dwSamplesPerSec;  // Sampling rate
	DWORD dwAvgBytesPerSec; // For buffer estimation
	WORD  wBlockAlign;      // Data block size
}

Field Summary

int	dwAvgBytesPerSec Average bytes per second.
int	dwSamplesPerSec Full sample rate.
short	wBlockAlign Block alignment.
short	wChannels Number of channels.
short	wFormatTag Indicates encoding format.

Constructor Summary

protected	WaveFormatChunk() Default constructor.
protected	WaveFormatChunk(RiffChunkReader rcr) Initializes from open chunk.

Method Summary

java.lang.Object	clone() Replicates instance.
abstract int	getSampleSize() Computes bytes per sample.
byte[]	toBytes() Serializes to bytes.
java.lang.String	toString() Serializes to string.
protected void	validateFields() Validates members.

Methods inherited from class java.lang.Object

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

Field Detail

wFormatTag

public short wFormatTag

Indicates encoding format.

Details: This member is a magic value that indicates the encoding format use for the wave file. Some possible values include:

WAVE_FORMAT_PCM	0x0001	Microsoft Pulse Code Modulation (PCM)
IBM_FORMAT_MULAW	0x0101	IBM mu-law format
IBM_FORMAT_ALAW	0x0102	IBM a-law format
IBM_FORMAT_ADPCM	0x0103	IBM AVC Adaptive Differential Pulse Code Modulation format

The value of this field also determines the presence of additional fields following the wBlockAlign field.

wChannels

public short wChannels

Number of channels.

Details: This member indicates the number of channels represented in the waveform data, i.e., 1 for mono, 2 for stereo, etc.

dwSamplesPerSec

public int dwSamplesPerSec

Full sample rate.

Details: This member indicates the number of samples per second, or the number of times per second each individual channel is sampled.

dwAvgBytesPerSec

public int dwAvgBytesPerSec

Average bytes per second.

Details: This member indicates the average number of bytes per second at which the waveform data will need to be processed. Playback and recording software can use this estimate when setting up buffers.

wBlockAlign

public short wBlockAlign

Block alignment.

Details: This member indicates the block alignment (in bytes) of the waveform data. Playback software will need to process data blocks of this size. This value can be used to ensure buffer alignment.

Constructor Detail

WaveFormatChunk

protected WaveFormatChunk()

Default constructor.

Details: This constructor initializes all members to 0.

WaveFormatChunk

protected WaveFormatChunk(RiffChunkReader rcr)
                   throws java.io.IOException

Initializes from open chunk.

Details: This constructor initializes the members of this WaveFormatChunk with values read from the given RIFF chunk. It is convenient to use this constructor when parsing wave format chunks.

Parameters:

the - RIFF chunk to process as a WaveFormatChunk

Method Detail

validateFields

protected void validateFields()
                       throws lava.io.FileFormatException

Validates members.

Details: This method verifies that the values of this format chunk's fields actually make sense. If they do not, a FileFormatException is thrown.

Throws:

if - the field are not valid

getSampleSize

public abstract int getSampleSize()

Computes bytes per sample.

Details: This method returns the number of bytes per sample. :

Details: getSampleSize returns the number of bytes required to contain a single, full sample. The value is determined by considering the number of bits per channel sample and the number of channels, as follows:

bits per channel sample	mono	stereo
1-8	1 byte	2 bytes
9-16	2 byte	4 bytes
17-24	3 byte	6 bytes
25-32	4 byte	8 bytes

These values are calculated without allowing bits from different channel samples to be packed into the same byte.

Returns:

number of bytes in full sample

toBytes

public byte[] toBytes()

Serializes to bytes.

Details: toBytes serializes this chunk into a string of bytes, as it would appear in a .wav file.

Returns:

this chunk in byte array form

toString

public java.lang.String toString()

Serializes to string.

Details: toString produces a string representation of this chunk. This representation is useful for debugging.

Overrides:

toString in class java.lang.Object

Returns:

string representation

clone

public final java.lang.Object clone()

Replicates instance.

Details: This method returns a perfect replica of this instance.

Overrides:

clone in class java.lang.Object

Returns:

replica