helliker.id3
Class MPEGAudioFrameHeader

java.lang.Object
  helliker.id3.MPEGAudioFrameHeader

public class MPEGAudioFrameHeader

extends java.lang.Object

Field Summary

private int	bitRate
private int[][]	bitrateTable
private java.lang.String[]	channelLabels
private int	channelMode
private boolean	copyrighted
private boolean	crced
private int	emphasis
private java.lang.String[]	emphasisLabels
private int	frameLength
private int	HEADER_SIZE
private int	layer
private java.lang.String[]	layerLabels
private long	location
static int	MONO_MODE
private java.io.File	mp3
static int	MPEG_L_1
static int	MPEG_L_2
static int	MPEG_L_3
static int	MPEG_V_1
static int	MPEG_V_2
static int	MPEG_V_25
private boolean	original
private boolean	padding
private boolean	privateBit
private int	sampleRate
private int[][]	sampleTable
private int[]	slotLength
private int	version
private java.lang.String[]	versionLabels
private XingVBRHeader	xingHead

Constructor Summary

MPEGAudioFrameHeader(java.io.File mp3)
Create an MPEGAudioFrameHeader from the file specified.

MPEGAudioFrameHeader(java.io.File mp3, int offset)
Create an MPEGAudioFrameHeader from the file specified.

Method Summary

private void	findBitRate(int bitrateIndex) Based on the bitrate index found in the header, try to find and set the bitrate from the table.
private long	findFrame(java.io.RandomAccessFile raf, int offset) Searches through the file and finds the first occurrence of an mpeg frame.
private void	findSampleRate(int sampleIndex) Based on the sample rate index found in the header, attempt to lookup and set the sample rate from the table.
int	getBitRate() Returns the bitrate of this mpeg.
java.lang.String	getChannelMode() Return the channel mode of the mpeg in string form.
java.lang.String	getEmphasis() Returns the emphasis.
int	getFrameLength() Computes the length of the frame found.
java.lang.String	getLayer() Return the layer description of the mpeg in string form.
long	getLocation() Returns the offset at which the first mpeg frame was found in the file.
int	getSampleRate() Returns the sample rate of the mpeg in Hz
int	getVBRPlayingTime() If this is a VBR file, return an accurate playing time of this mpeg.
java.lang.String	getVersion() Return the version of the mpeg in string form.
boolean	hasPadding() Returns true if the mpeg frames are padded in this file.
boolean	isCopyrighted() Returns true if the audio is copyrighted
boolean	isMP3() Returns true if the file passed to the constructor is an mp3 (MPEG layer III).
boolean	isOriginal() Returns true if this is the original media
boolean	isProtected() Returns true if this mpeg is protected by CRC
boolean	isVBR()
boolean	privateBitSet() Returns true if the private bit is set.
private void	readHeader(java.io.RandomAccessFile raf, long location) Read in all the information found in the mpeg header.
java.lang.String	toString() Return a string representation of this object.

Methods inherited from class java.lang.Object

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

Field Detail

MPEG_V_25

public static final int MPEG_V_25

See Also:

Constant Field Values

MPEG_V_2

public static final int MPEG_V_2

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Constant Field Values

MPEG_V_1

public static final int MPEG_V_1

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Constant Field Values

MPEG_L_3

public static final int MPEG_L_3

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Constant Field Values

MPEG_L_2

public static final int MPEG_L_2

See Also:

Constant Field Values

MPEG_L_1

public static final int MPEG_L_1

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Constant Field Values

MONO_MODE

public static final int MONO_MODE

See Also:

Constant Field Values

HEADER_SIZE

private final int HEADER_SIZE

See Also:

Constant Field Values

bitrateTable

private final int[][] bitrateTable

sampleTable

private final int[][] sampleTable

versionLabels

private final java.lang.String[] versionLabels

layerLabels

private final java.lang.String[] layerLabels

channelLabels

private final java.lang.String[] channelLabels

emphasisLabels

private final java.lang.String[] emphasisLabels

slotLength

private final int[] slotLength

xingHead

private XingVBRHeader xingHead

mp3

private java.io.File mp3

version

private int version

layer

private int layer

bitRate

private int bitRate

sampleRate

private int sampleRate

channelMode

private int channelMode

copyrighted

private boolean copyrighted

crced

private boolean crced

original

private boolean original

privateBit

private boolean privateBit

emphasis

private int emphasis

location

private long location

frameLength

private int frameLength

padding

private boolean padding

Constructor Detail

MPEGAudioFrameHeader

public MPEGAudioFrameHeader(java.io.File mp3)
                     throws NoMPEGFramesException,
                            java.io.FileNotFoundException,
                            java.io.IOException,
                            CorruptHeaderException

Create an MPEGAudioFrameHeader from the file specified. Upon creation information will be read in from the first frame header the object encounters in the file.

Parameters:

mp3 - the file to read from

Throws:

NoMPEGFramesException - if the file is not a valid mpeg

java.io.FileNotFoundException - if an error occurs

java.io.IOException - if an error occurs

CorruptHeaderException - if an error occurs

MPEGAudioFrameHeader

public MPEGAudioFrameHeader(java.io.File mp3,
                            int offset)
                     throws NoMPEGFramesException,
                            java.io.FileNotFoundException,
                            java.io.IOException,
                            CorruptHeaderException

Create an MPEGAudioFrameHeader from the file specified. Upon creation information will be read in from the first frame header the object encounters in the file. The offset tells the object where to start searching for an MPEG frame. If you know the size of an id3v2 tag attached to the file and pass it to this ctor, it will take less time to find the frame.

Parameters:

mp3 - the file to read from

offset - the offset to start searching from

Throws:

NoMPEGFramesException - if the file is not a valid mpeg

java.io.FileNotFoundException - if an error occurs

java.io.IOException - if an error occurs

CorruptHeaderException - if an error occurs

Method Detail

findFrame

private long findFrame(java.io.RandomAccessFile raf,
                       int offset)
                throws java.io.IOException

Searches through the file and finds the first occurrence of an mpeg frame. Returns the location of the header of the frame.

Parameters:

raf - the open file to find the frame in

offset - the offset to start searching from

Returns:

the location of the header of the frame

Throws:

java.io.IOException - if an error occurs

readHeader

private void readHeader(java.io.RandomAccessFile raf,
                        long location)
                 throws java.io.IOException,
                        CorruptHeaderException

Read in all the information found in the mpeg header.

Parameters:

raf - the open file to find the frame in

location - the location of the header (found by findFrame)

Throws:

CorruptHeaderException - if an error occurs

java.io.IOException - if an error occurs

findBitRate

private void findBitRate(int bitrateIndex)

Based on the bitrate index found in the header, try to find and set the bitrate from the table.

Parameters:

bitrateIndex - the bitrate index read from the header

findSampleRate

private void findSampleRate(int sampleIndex)

Based on the sample rate index found in the header, attempt to lookup and set the sample rate from the table.

Parameters:

sampleIndex - the sample rate index read from the header

getFrameLength

public int getFrameLength()

Computes the length of the frame found. This is not necessarily constant for all frames.

Returns:

the length of the frame found

toString

public java.lang.String toString()

Return a string representation of this object. Includes all information read in.

Returns:

a string representation of this object

getVersion

public java.lang.String getVersion()

Return the version of the mpeg in string form. Ex: MPEG Version 1.0

Returns:

the version of the mpeg

getLayer

public java.lang.String getLayer()

Return the layer description of the mpeg in string form. Ex: Layer III

Returns:

the layer description of the mpeg

getChannelMode

public java.lang.String getChannelMode()

Return the channel mode of the mpeg in string form. Ex: Joint Stereo (STEREO)

Returns:

the channel mode of the mpeg

getSampleRate

public int getSampleRate()

Returns the sample rate of the mpeg in Hz

Returns:

the sample rate of the mpeg in Hz

isCopyrighted

public boolean isCopyrighted()

Returns true if the audio is copyrighted

Returns:

true if the audio is copyrighted

isProtected

public boolean isProtected()

Returns true if this mpeg is protected by CRC

Returns:

true if this mpeg is protected by CRC

isOriginal

public boolean isOriginal()

Returns true if this is the original media

Returns:

true if this is the original media

isVBR

public boolean isVBR()

getEmphasis

public java.lang.String getEmphasis()

Returns the emphasis. I don't know what this means, it just does it...

Returns:

the emphasis

getLocation

public long getLocation()

Returns the offset at which the first mpeg frame was found in the file.

Returns:

the offset of the mpeg data

isMP3

public boolean isMP3()

Returns true if the file passed to the constructor is an mp3 (MPEG layer III).

Returns:

true if the file is an mp3

hasPadding

public boolean hasPadding()

Returns true if the mpeg frames are padded in this file.

Returns:

true if the mpeg frames are padded in this file

privateBitSet

public boolean privateBitSet()

Returns true if the private bit is set.

Returns:

true if the private bit is set

getVBRPlayingTime

public int getVBRPlayingTime()

If this is a VBR file, return an accurate playing time of this mpeg. If this is not a VBR file -1 is returned.

Returns:

an accurate playing time of this mpeg

getBitRate

public int getBitRate()

Returns the bitrate of this mpeg. If it is a VBR file the average bitrate is returned.

Returns:

the bitrate of this mpeg (in kbps)