Package org.deepsymmetry.beatlink.data

Class BeatGrid

java.lang.Object

org.deepsymmetry.beatlink.data.BeatGrid

public class BeatGrid
extends Object

Provides information about each beat in a track: the number of milliseconds after the start of the track that the beat occurs, and where the beat falls within a measure.

Author:

James Elliott

Field Summary

Fields

Modifier and Type	Field	Description
int	beatCount	The number of beats in the track.
DataReference	dataReference	The unique identifier that was used to request this beat grid.

Constructor Summary

Constructors

Constructor	Description
BeatGrid(DataReference reference, int[] beatWithinBarValues, int[] bpmValues, long[] timeWithinTrackValues)	Constructor for use by an external storage system.
BeatGrid(DataReference reference, ByteBuffer buffer)	Constructor for reading from a file.
BeatGrid(DataReference reference, Message message)	Constructor for when reading from the network.
BeatGrid(DataReference reference, RekordboxAnlz anlzFile)	Constructor for when fetched from Crate Digger.

Method Summary

Modifier and Type	Method	Description
int	findBeatAtTime(long milliseconds)	Finds the beat in which the specified track position falls.
int	getBarNumber(int beatNumber)	Return the bar number within which the specified beat falls.
int	getBeatWithinBar(int beatNumber)	Returns the musical count of the specified beat, represented by Bb in the Packet Analysis document.
int	getBpm(int beatNumber)	Get the track BPM at the time of a beat.
ByteBuffer	getRawData()	Get the raw bytes of the beat grid as it was read over the network.
long	getTimeWithinTrack(int beatNumber)	Returns the time at which the specified beat falls within the track.
String	toString()

Methods inherited from class java.lang.Object

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

Field Detail

dataReference

public final DataReference dataReference

The unique identifier that was used to request this beat grid.

beatCount

public final int beatCount

The number of beats in the track.

Constructor Detail

BeatGrid

public BeatGrid(DataReference reference,
                Message message)

Constructor for when reading from the network.

Parameters:

reference - the unique database reference that was used to request this waveform detail

message - the response that contained the beat grid data

BeatGrid

public BeatGrid(DataReference reference,
                ByteBuffer buffer)

Constructor for reading from a file.

Parameters:

reference - the unique database reference that was used to request this waveform detail

buffer - the raw bytes representing the beat grid

BeatGrid

public BeatGrid(DataReference reference,
                RekordboxAnlz anlzFile)

Constructor for when fetched from Crate Digger.

Parameters:

reference - the unique database reference that was used to request this waveform detail

anlzFile - the parsed rekordbox track analysis file containing the waveform preview

BeatGrid

public BeatGrid(DataReference reference,
                int[] beatWithinBarValues,
                int[] bpmValues,
                long[] timeWithinTrackValues)

Constructor for use by an external storage system.

Parameters:

reference - the unique database reference that was used to request this waveform detail

beatWithinBarValues - the musical time on which each beat in the grid falls

bpmValues - the tempo of the track at each beat, as beats per minute multiplied by 100

timeWithinTrackValues - the time, in milliseconds, at which each beat occurs in the track

Method Detail

getRawData

public ByteBuffer getRawData()

Get the raw bytes of the beat grid as it was read over the network. This can be used to analyze fields that have not yet been reliably understood, and is also used for storing the beat grid in a file. This is not available when the beat grid was loaded by Crate Digger.

Returns:

the bytes that make up the beat grid

getTimeWithinTrack

public long getTimeWithinTrack(int beatNumber)

Returns the time at which the specified beat falls within the track. Beat 0 means we are before the first beat (e.g. ready to play the track), so we return 0.

Parameters:

beatNumber - the beat number desired, must fall within the range 1..beatCount

Returns:

the number of milliseconds into the track at which the specified beat occurs

Throws:

IllegalArgumentException - if number is less than 0 or greater than beatCount

getBeatWithinBar

public int getBeatWithinBar(int beatNumber)

Returns the musical count of the specified beat, represented by B_b in the Packet Analysis document. A number from 1 to 4, where 1 is the downbeat, or the start of a new measure.

Parameters:

beatNumber - the number of the beat of interest, must fall within the range 1..beatCount

Returns:

where that beat falls in a bar of music

Throws:

IllegalArgumentException - if number is less than 1 or greater than beatCount

getBpm

public int getBpm(int beatNumber)

Get the track BPM at the time of a beat. This is an integer representing the BPM times 100, so a track running at 120.5 BPM would be represented by the value 12050.

Parameters:

beatNumber - the beat number desired, must fall within the range 1..beatCount

Returns:

the track BPM at the specified beat number to two decimal places multiplied by 100

getBarNumber

public int getBarNumber(int beatNumber)

Return the bar number within which the specified beat falls. Like beats, bars are numbered starting at 1. Handles the case where the first bar is incomplete (the first beat is not a downbeat); like rekordbox, in such cases bar 1 is the fist complete bar, and the preceding bar is bar -1.

Parameters:

beatNumber - the beat number whose bar number is desired

Returns:

the bar within which the specified beat falls

findBeatAtTime

public int findBeatAtTime(long milliseconds)

Finds the beat in which the specified track position falls.

Parameters:

milliseconds - how long the track has been playing

Returns:

the beat number represented by that time, or -1 if the time is before the first beat

toString

public String toString()

Overrides:

toString in class Object