org.openimaj.audio

Class SampleChunk

java.lang.Object

org.openimaj.audio.Audio

org.openimaj.audio.SampleChunk

public class SampleChunk
extends Audio

Represents a chunk of an audio file and stores the raw audio data. The data is unnormalised - that is, it is stored in this class in its original format in the form of a byte array. This is for speed during audio playback. If you require normalised data (data as an integer array for example) use the method getSamplesAsByteBuffer() and use the ByteBuffer's methods asXXXBuffer (e.g. ByteBuffer#asShortBuffer) to get the samples in a normalised form.

Author:

David Dupplaw (dpd@ecs.soton.ac.uk)

Created:

8 Jun 2011

Field Summary

Fields inherited from class org.openimaj.audio.Audio

format

Constructor Summary

Constructors

Constructor and Description
SampleChunk(AudioFormat af) Create a new SampleChunk buffer with the given audio format, but do not initialise the samples.
SampleChunk(byte[] samples, AudioFormat af) Create a new sample chunk using the given samples and the given audio format.
SampleChunk(byte[] samples, AudioFormat af, AudioTimecode tc) Create a new sample chunk using the given samples and the given audio format.

Method Summary

Modifier and Type	Method and Description
SampleChunk	append(SampleChunk sample) Appends the given samples to the end of this sample chunk.
SampleChunk	clone()
int	getNumberOfSamples() Returns the number of samples in this sample chunk.
SampleBuffer	getSampleBuffer() Returns an appropriate sample buffer for this sample chunk.
byte[]	getSamples() Get the samples in this sample chunk
ByteBuffer	getSamplesAsByteBuffer() Returns a ByteBuffer that can be used to create views of the samples in the object.
SampleChunk	getSampleSlice(int start, int length) Return a slice of data from the sample array.
AudioTimecode	getStartTimecode() Get the timecode at the start of this audio chunk.
void	pad(int requiredSampleSetSize) Pads the sample chunk to the given size with zeros.
SampleChunk	prepend(SampleChunk sample) Prepends the given samples to the front of this sample chunk.
void	setSamples(byte[] samples) Set the samples in this sample chunk.
void	setStartTimecode(AudioTimecode startTimecode) Set the timecode at the start of this audio chunk.

Methods inherited from class org.openimaj.audio.Audio

getFormat, setFormat

Methods inherited from class java.lang.Object

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

Constructor Detail

SampleChunk

public SampleChunk(AudioFormat af)

Create a new SampleChunk buffer with the given audio format, but do not initialise the samples.

Parameters:

af - The audio format of the samples

SampleChunk

public SampleChunk(byte[] samples,
                   AudioFormat af)

Create a new sample chunk using the given samples and the given audio format.

Parameters:

samples - The samples to initialise with

af - The audio format of the samples

SampleChunk

public SampleChunk(byte[] samples,
                   AudioFormat af,
                   AudioTimecode tc)

Create a new sample chunk using the given samples and the given audio format.

Parameters:

samples - The samples to initialise with

af - The audio format of the samples

tc - The audio timecode of these samples

Method Detail

setSamples

public void setSamples(byte[] samples)

Set the samples in this sample chunk.

Parameters:

samples - the samples in this sample chunk.

getSamples

public byte[] getSamples()

Get the samples in this sample chunk

Returns:

the samples in this sample chunk

getNumberOfSamples

public int getNumberOfSamples()

Returns the number of samples in this sample chunk. If there are 128 stereo samples, this method will return 256. That is, it does not normalise for the number of channels. However, it does normalise for the size of each sample. So if this is a 16-bit buffer of 256 bytes length, this method will return 128.

Returns:

the number of samples in this sample chunk.

getSamplesAsByteBuffer

public ByteBuffer getSamplesAsByteBuffer()

Returns a ByteBuffer that can be used to create views of the samples in the object. For example, to get short integers, you can get getSamplesAsByteBuffer().asShortBuffer()

Returns:

A ByteBuffer

getSampleBuffer

public SampleBuffer getSampleBuffer()

Returns an appropriate sample buffer for this sample chunk. If an appropriate sample buffer cannot be found, null will be returned. This will wrap the samples array from the underlying chunk, so you should only side-affect the samples if you're sure they will not be reused.

Returns:

An appropriate SampleBuffer

setStartTimecode

public void setStartTimecode(AudioTimecode startTimecode)

Set the timecode at the start of this audio chunk.

Parameters:

startTimecode - the timecode at the start of the chunk.

getStartTimecode

public AudioTimecode getStartTimecode()

Get the timecode at the start of this audio chunk.

Returns:

the timecode at the start of the chunk.

getSampleSlice

public SampleChunk getSampleSlice(int start,
                                  int length)

Return a slice of data from the sample array. The indices are based on the samples in the byte array, not the bytes themselves.

The assumption is that samples are whole numbers of bytes. So, if the sample size was 16-bits, then passing in 2 for the start index would actually index the byte at index 4 in the underlying sample array. The order of the bytes is unchanged.

Parameters:

start - The start index of the sample.

length - The length of the samples get.

Returns:

The sample slice as a new SampleChunk

prepend

public SampleChunk prepend(SampleChunk sample)

Prepends the given samples to the front of this sample chunk. It is expected that the given samples are in the same format as this sample chunk; if they are not an exception is thrown. Side-affects this sample chunk and will return a reference to this sample chunk.

Parameters:

sample - the samples to add

Returns:

This sample chunk with the bytes prepended

append

public SampleChunk append(SampleChunk sample)

Appends the given samples to the end of this sample chunk. It is expected that the given samples are in the same format as this sample chunk; if they are not an exception is thrown. Side-affects this sample chunk and will return a reference to this sample chunk.

Parameters:

sample - the samples to add

Returns:

This sample chunk with the bytes appended

clone

public SampleChunk clone()

Overrides:

clone in class Object

pad

public void pad(int requiredSampleSetSize)

Pads the sample chunk to the given size with zeros.

Parameters:

requiredSampleSetSize - The required sample size