ResamplingAudioSource Class Reference

A type of AudioSource that takes an input source and changes its sample rate. More...

Inherits AudioSource.

List of all members.

Classes

struct  FilterState

Public Member Functions

 ResamplingAudioSource (AudioSource *const inputSource, const bool deleteInputWhenDeleted)
 Creates a ResamplingAudioSource for a given input source.
 ~ResamplingAudioSource ()
 Destructor.
void setResamplingRatio (const double samplesInPerOutputSample)
 Changes the resampling ratio.
double getResamplingRatio () const throw ()
 Returns the current resampling ratio.
void prepareToPlay (int samplesPerBlockExpected, double sampleRate)
 Tells the source to prepare for playing.
void releaseResources ()
 Allows the source to release anything it no longer needs after playback has stopped.
void getNextAudioBlock (const AudioSourceChannelInfo &bufferToFill)
 Called repeatedly to fetch subsequent blocks of audio data.

Detailed Description

A type of AudioSource that takes an input source and changes its sample rate.

See also:
AudioSource

Constructor & Destructor Documentation

ResamplingAudioSource::ResamplingAudioSource ( AudioSource *const   inputSource,
const bool  deleteInputWhenDeleted 
)

Creates a ResamplingAudioSource for a given input source.

Parameters:
inputSource the input source to read from
deleteInputWhenDeleted if true, the input source will be deleted when this object is deleted
ResamplingAudioSource::~ResamplingAudioSource (  ) 

Destructor.


Member Function Documentation

void ResamplingAudioSource::setResamplingRatio ( const double  samplesInPerOutputSample  ) 

Changes the resampling ratio.

(This value can be changed at any time, even while the source is running).

Parameters:
samplesInPerOutputSample if set to 1.0, the input is passed through; higher values will speed it up; lower values will slow it down. The ratio must be greater than 0
double ResamplingAudioSource::getResamplingRatio (  )  const throw ()

Returns the current resampling ratio.

This is the value that was set by setResamplingRatio().

void ResamplingAudioSource::prepareToPlay ( int  samplesPerBlockExpected,
double  sampleRate 
) [virtual]

Tells the source to prepare for playing.

The source can use this opportunity to initialise anything it needs to.

Note that this method could be called more than once in succession without a matching call to releaseResources(), so make sure your code is robust and can handle that kind of situation.

Parameters:
samplesPerBlockExpected the number of samples that the source will be expected to supply each time its getNextAudioBlock() method is called. This number may vary slightly, because it will be dependent on audio hardware callbacks, and these aren't guaranteed to always use a constant block size, so the source should be able to cope with small variations.
sampleRate the sample rate that the output will be used at - this is needed by sources such as tone generators.
See also:
releaseResources, getNextAudioBlock

Implements AudioSource.

void ResamplingAudioSource::releaseResources (  )  [virtual]

Allows the source to release anything it no longer needs after playback has stopped.

This will be called when the source is no longer going to have its getNextAudioBlock() method called, so it should release any spare memory, etc. that it might have allocated during the prepareToPlay() call.

Note that there's no guarantee that prepareToPlay() will actually have been called before releaseResources(), and it may be called more than once in succession, so make sure your code is robust and doesn't make any assumptions about when it will be called.

See also:
prepareToPlay, getNextAudioBlock

Implements AudioSource.

void ResamplingAudioSource::getNextAudioBlock ( const AudioSourceChannelInfo bufferToFill  )  [virtual]

Called repeatedly to fetch subsequent blocks of audio data.

After calling the prepareToPlay() method, this callback will be made each time the audio playback hardware (or whatever other destination the audio data is going to) needs another block of data.

It will generally be called on a high-priority system thread, or possibly even an interrupt, so be careful not to do too much work here, as that will cause audio glitches!

See also:
AudioSourceChannelInfo, prepareToPlay, releaseResources

Implements AudioSource.


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