Buffer Processor prototypes. A Buffer Processor performs buffer length adaption, coordinates sample format conversion, and interleaves/deinterleaves channels. More...

#include "portaudio.h"
#include "pa_converters.h"
#include "pa_dither.h"

Data Structures
struct	PaUtilChannelDescriptor
	An auxiliary data structure used internally by the buffer processor to represent host input and output buffers. More...

struct	PaUtilBufferProcessor
	The main buffer processor data structure. More...

Typedefs
typedef struct PaUtilChannelDescriptor	PaUtilChannelDescriptor
	An auxiliary data structure used internally by the buffer processor to represent host input and output buffers. More...

Enumerations
enum	PaUtilHostBufferSizeMode { paUtilFixedHostBufferSize, paUtilBoundedHostBufferSize, paUtilUnknownHostBufferSize, paUtilVariableHostBufferSizePartialUsageAllowed }
	Mode flag passed to PaUtil_InitializeBufferProcessor indicating the type of buffering that the host API uses. More...

Functions
Initialization, termination, resetting and info
PaError	PaUtil_InitializeBufferProcessor (PaUtilBufferProcessor bufferProcessor, int inputChannelCount, PaSampleFormat userInputSampleFormat, PaSampleFormat hostInputSampleFormat, int outputChannelCount, PaSampleFormat userOutputSampleFormat, PaSampleFormat hostOutputSampleFormat, double sampleRate, PaStreamFlags streamFlags, unsigned long framesPerUserBuffer, unsigned long framesPerHostBuffer, PaUtilHostBufferSizeMode hostBufferSizeMode, PaStreamCallback streamCallback, void *userData)

void	PaUtil_TerminateBufferProcessor (PaUtilBufferProcessor *bufferProcessor)

void	PaUtil_ResetBufferProcessor (PaUtilBufferProcessor *bufferProcessor)

unsigned long	PaUtil_GetBufferProcessorInputLatencyFrames (PaUtilBufferProcessor *bufferProcessor)

unsigned long	PaUtil_GetBufferProcessorOutputLatencyFrames (PaUtilBufferProcessor *bufferProcessor)

Host buffer pointer configuration
Functions to set host input and output buffers, used by both callback streams and blocking read/write streams.
void	PaUtil_SetInputFrameCount (PaUtilBufferProcessor *bufferProcessor, unsigned long frameCount)

void	PaUtil_SetNoInput (PaUtilBufferProcessor *bufferProcessor)

void	PaUtil_SetInputChannel (PaUtilBufferProcessor bufferProcessor, unsigned int channel, void data, unsigned int stride)

void	PaUtil_SetInterleavedInputChannels (PaUtilBufferProcessor bufferProcessor, unsigned int firstChannel, void data, unsigned int channelCount)

void	PaUtil_SetNonInterleavedInputChannel (PaUtilBufferProcessor bufferProcessor, unsigned int channel, void data)

void	PaUtil_Set2ndInputFrameCount (PaUtilBufferProcessor *bufferProcessor, unsigned long frameCount)

void	PaUtil_Set2ndInputChannel (PaUtilBufferProcessor bufferProcessor, unsigned int channel, void data, unsigned int stride)

void	PaUtil_Set2ndInterleavedInputChannels (PaUtilBufferProcessor bufferProcessor, unsigned int firstChannel, void data, unsigned int channelCount)

void	PaUtil_Set2ndNonInterleavedInputChannel (PaUtilBufferProcessor bufferProcessor, unsigned int channel, void data)

void	PaUtil_SetOutputFrameCount (PaUtilBufferProcessor *bufferProcessor, unsigned long frameCount)

void	PaUtil_SetNoOutput (PaUtilBufferProcessor *bufferProcessor)

void	PaUtil_SetOutputChannel (PaUtilBufferProcessor bufferProcessor, unsigned int channel, void data, unsigned int stride)

void	PaUtil_SetInterleavedOutputChannels (PaUtilBufferProcessor bufferProcessor, unsigned int firstChannel, void data, unsigned int channelCount)

void	PaUtil_SetNonInterleavedOutputChannel (PaUtilBufferProcessor bufferProcessor, unsigned int channel, void data)

void	PaUtil_Set2ndOutputFrameCount (PaUtilBufferProcessor *bufferProcessor, unsigned long frameCount)

void	PaUtil_Set2ndOutputChannel (PaUtilBufferProcessor bufferProcessor, unsigned int channel, void data, unsigned int stride)

void	PaUtil_Set2ndInterleavedOutputChannels (PaUtilBufferProcessor bufferProcessor, unsigned int firstChannel, void data, unsigned int channelCount)

void	PaUtil_Set2ndNonInterleavedOutputChannel (PaUtilBufferProcessor bufferProcessor, unsigned int channel, void data)

Buffer processing functions for callback streams
void	PaUtil_BeginBufferProcessing (PaUtilBufferProcessor bufferProcessor, PaStreamCallbackTimeInfo timeInfo, PaStreamCallbackFlags callbackStatusFlags)

unsigned long	PaUtil_EndBufferProcessing (PaUtilBufferProcessor bufferProcessor, int callbackResult)

int	PaUtil_IsBufferProcessorOutputEmpty (PaUtilBufferProcessor *bufferProcessor)

Buffer processing functions for blocking read/write streams
unsigned long	PaUtil_CopyInput (PaUtilBufferProcessor bufferProcessor, void *buffer, unsigned long frameCount)

unsigned long	PaUtil_CopyOutput (PaUtilBufferProcessor bufferProcessor, const void *buffer, unsigned long frameCount)

unsigned long	PaUtil_ZeroOutput (PaUtilBufferProcessor *bufferProcessor, unsigned long frameCount)

Detailed Description

Buffer Processor prototypes. A Buffer Processor performs buffer length adaption, coordinates sample format conversion, and interleaves/deinterleaves channels.

Overview

The "Buffer Processor" (PaUtilBufferProcessor) manages conversion of audio data from host buffers to user buffers and back again. Where required, the buffer processor takes care of converting between host and user sample formats, interleaving and deinterleaving multichannel buffers, and adapting between host and user buffers with different lengths. The buffer processor may be used with full and half duplex streams, for both callback streams and blocking read/write streams.

One of the important capabilities provided by the buffer processor is the ability to adapt between user and host buffer sizes of different lengths with minimum latency. Although this task is relatively easy to perform when the host buffer size is an integer multiple of the user buffer size, the problem is more complicated when this is not the case - especially for full-duplex callback streams. Where necessary the adaption is implemented by internally buffering some input and/or output data. The buffer adation algorithm used by the buffer processor was originally implemented by Stephan Letz for the ASIO version of PortAudio, and is described in his Callback_adaption_.pdf which is included in the distribution.

The buffer processor performs sample conversion using the functions provided by pa_converters.c.

The following sections provide an overview of how to use the buffer processor. Interested readers are advised to consult the host API implementations for examples of buffer processor usage.

Initialization, resetting and termination

When a stream is opened, the buffer processor should be initialized using PaUtil_InitializeBufferProcessor. This function initializes internal state and allocates temporary buffers as necessary according to the supplied configuration parameters. Some of the parameters correspond to those requested by the user in their call to Pa_OpenStream(), others reflect the requirements of the host API implementation - they indicate host buffer sizes, formats, and the type of buffering which the Host API uses. The buffer processor should be initialized for callback streams and blocking read/write streams.

Call PaUtil_ResetBufferProcessor to clear any sample data which is present in the buffer processor before starting to use it (for example when Pa_StartStream is called).

When the buffer processor is no longer used call PaUtil_TerminateBufferProcessor.

Using the buffer processor for a callback stream

The buffer processor's role in a callback stream is to take host input buffers process them with the stream callback, and fill host output buffers. For a full duplex stream, the buffer processor handles input and output simultaneously due to the requirements of the minimum-latency buffer adation algorithm.

When a host buffer becomes available, the implementation should call the buffer processor to process the buffer. The buffer processor calls the stream callback to consume and/or produce audio data as necessary. The buffer processor will convert sample formats, interleave/deinterleave channels, and slice or chunk the data to the appropriate buffer lengths according to the requirements of the stream callback and the host API.

To process a host buffer (or a pair of host buffers for a full-duplex stream) use the following calling sequence:

Call PaUtil_BeginBufferProcessing
For a stream which takes input:
- Call PaUtil_SetInputFrameCount with the number of frames in the host input buffer.
- Call one of the following functions one or more times to tell the buffer processor about the host input buffer(s): PaUtil_SetInputChannel, PaUtil_SetInterleavedInputChannels, PaUtil_SetNonInterleavedInputChannel. Which function you call will depend on whether the host buffer(s) are interleaved or not.
- If the available host data is split across two buffers (for example a data range at the end of a circular buffer and another range at the beginning of the circular buffer), also call PaUtil_Set2ndInputFrameCount, PaUtil_Set2ndInputChannel, PaUtil_Set2ndInterleavedInputChannels, PaUtil_Set2ndNonInterleavedInputChannel as necessary to tell the buffer processor about the second buffer.
For a stream which generates output:
- Call PaUtil_SetOutputFrameCount with the number of frames in the host output buffer.
- Call one of the following functions one or more times to tell the buffer processor about the host output buffer(s): PaUtil_SetOutputChannel, PaUtil_SetInterleavedOutputChannels, PaUtil_SetNonInterleavedOutputChannel. Which function you call will depend on whether the host buffer(s) are interleaved or not.
- If the available host output buffer space is split across two buffers (for example a data range at the end of a circular buffer and another range at the beginning of the circular buffer), call PaUtil_Set2ndOutputFrameCount, PaUtil_Set2ndOutputChannel, PaUtil_Set2ndInterleavedOutputChannels, PaUtil_Set2ndNonInterleavedOutputChannel as necessary to tell the buffer processor about the second buffer.
Call PaUtil_EndBufferProcessing, this function performs the actual data conversion and processing.

Using the buffer processor for a blocking read/write stream

Blocking read/write streams use the buffer processor to convert and copy user output data to a host buffer, and to convert and copy host input data to the user's buffer. The buffer processor does not perform any buffer adaption. When using the buffer processor in a blocking read/write stream the input and output conversion are performed separately by the PaUtil_CopyInput and PaUtil_CopyOutput functions.

To copy data from a host input buffer to the buffer(s) which the user supplies to Pa_ReadStream, use the following calling sequence.

Repeat the following three steps until the user buffer(s) have been filled with samples from the host input buffers:
1. Call PaUtil_SetInputFrameCount with the number of frames in the host input buffer.
2. Call one of the following functions one or more times to tell the buffer processor about the host input buffer(s): PaUtil_SetInputChannel, PaUtil_SetInterleavedInputChannels, PaUtil_SetNonInterleavedInputChannel. Which function you call will depend on whether the host buffer(s) are interleaved or not.
3. Call PaUtil_CopyInput with the user buffer pointer (or a copy of the array of buffer pointers for a non-interleaved stream) passed to Pa_ReadStream, along with the number of frames in the user buffer(s). Be careful to pass a copy of the user buffer pointers to PaUtil_CopyInput because PaUtil_CopyInput advances the pointers to the start of the next region to copy.
PaUtil_CopyInput will not copy more data than is available in the host buffer(s), so the above steps need to be repeated until the user buffer(s) are full.

To copy data to the host output buffer from the user buffers(s) supplied to Pa_WriteStream use the following calling sequence.

Repeat the following three steps until all frames from the user buffer(s) have been copied to the host API:
1. Call PaUtil_SetOutputFrameCount with the number of frames in the host output buffer.
2. Call one of the following functions one or more times to tell the buffer processor about the host output buffer(s): PaUtil_SetOutputChannel, PaUtil_SetInterleavedOutputChannels, PaUtil_SetNonInterleavedOutputChannel. Which function you call will depend on whether the host buffer(s) are interleaved or not.
3. Call PaUtil_CopyOutput with the user buffer pointer (or a copy of the array of buffer pointers for a non-interleaved stream) passed to Pa_WriteStream, along with the number of frames in the user buffer(s). Be careful to pass a copy of the user buffer pointers to PaUtil_CopyOutput because PaUtil_CopyOutput advances the pointers to the start of the next region to copy.
PaUtil_CopyOutput will not copy more data than fits in the host buffer(s), so the above steps need to be repeated until all user data is copied.

Typedef Documentation

typedef struct PaUtilChannelDescriptor PaUtilChannelDescriptor

An auxiliary data structure used internally by the buffer processor to represent host input and output buffers.

Enumeration Type Documentation

enum PaUtilHostBufferSizeMode

Mode flag passed to PaUtil_InitializeBufferProcessor indicating the type of buffering that the host API uses.

The mode used depends on whether the host API or the implementation manages the buffers, and how these buffers are used (scatter gather, circular buffer).

Enumerator
paUtilFixedHostBufferSize	The host buffer size is a fixed known size.
paUtilBoundedHostBufferSize	The host buffer size may vary, but has a known maximum size.
paUtilUnknownHostBufferSize	Nothing is known about the host buffer size.
paUtilVariableHostBufferSizePartialUsageAllowed	The host buffer size varies, and the client does not require the buffer processor to consume all of the input and fill all of the output buffer. This is useful when the implementation has access to the host API's circular buffer and only needs to consume/fill some of it, not necessarily all of it, with each call to the buffer processor. This is the only mode where PaUtil_EndBufferProcessing() may not consume the whole buffer.

Function Documentation

void PaUtil_BeginBufferProcessing	(	PaUtilBufferProcessor *	bufferProcessor,
		PaStreamCallbackTimeInfo *	timeInfo,
		PaStreamCallbackFlags	callbackStatusFlags
	)

Commence processing a host buffer (or a pair of host buffers in the full-duplex case) for a callback stream.

Parameters

bufferProcessor	The buffer processor.
timeInfo	Timing information for the first sample of the host buffer(s). This information may be adjusted when buffer adaption is being performed.
callbackStatusFlags	Flags indicating whether underruns and overruns have occurred since the last time the buffer processor was called.

References PaUtilBufferProcessor::callbackStatusFlags, PaUtilBufferProcessor::framesInTempInputBuffer, PaUtilBufferProcessor::framesInTempOutputBuffer, PaUtilBufferProcessor::hostInputFrameCount, PaUtilBufferProcessor::hostOutputFrameCount, PaStreamCallbackTimeInfo::inputBufferAdcTime, PaStreamCallbackTimeInfo::outputBufferDacTime, PaUtilBufferProcessor::samplePeriod, and PaUtilBufferProcessor::timeInfo.

Referenced by ProcessingThreadProc().

unsigned long PaUtil_CopyInput	(	PaUtilBufferProcessor *	bufferProcessor,
		void **	buffer,
		unsigned long	frameCount
	)

Copy samples from host input channels set up by the PaUtil_Set*InputChannels functions to a user supplied buffer. This function is intended for use with blocking read/write streams. Copies the minimum of the number of user frames (specified by the frameCount parameter) and the number of available host frames (specified in a previous call to SetInputFrameCount()).

Parameters

bufferProcessor	The buffer processor.
buffer	A pointer to the user buffer pointer, or a pointer to a pointer to an array of user buffer pointers for a non-interleaved stream. It is important that this parameter points to a copy of the user buffer pointers, not to the actual user buffer pointers, because this function updates the pointers before returning.
frameCount	The number of frames of data in the buffer(s) pointed to by the buffer parameter.

Returns: The number of frames copied. The buffer pointer(s) pointed to by the buffer parameter are advanced to point to the frame(s) following the last one filled.

References PaUtilBufferProcessor::bytesPerHostInputSample, PaUtilBufferProcessor::bytesPerUserInputSample, PaUtilChannelDescriptor::data, PaUtilBufferProcessor::ditherGenerator, PaUtilBufferProcessor::hostInputChannels, PaUtilBufferProcessor::hostInputFrameCount, PaUtilBufferProcessor::inputChannelCount, PaUtilBufferProcessor::inputConverter, PA_MIN_, PaUtilChannelDescriptor::stride, and PaUtilBufferProcessor::userInputIsInterleaved.

unsigned long PaUtil_CopyOutput	(	PaUtilBufferProcessor *	bufferProcessor,
		const void **	buffer,
		unsigned long	frameCount
	)

References PaUtilBufferProcessor::bytesPerHostOutputSample, PaUtilBufferProcessor::bytesPerUserOutputSample, PaUtilChannelDescriptor::data, PaUtilBufferProcessor::ditherGenerator, PaUtilBufferProcessor::hostOutputChannels, PaUtilBufferProcessor::hostOutputFrameCount, PaUtilBufferProcessor::outputChannelCount, PaUtilBufferProcessor::outputConverter, PA_MIN_, PaUtilChannelDescriptor::stride, and PaUtilBufferProcessor::userOutputIsInterleaved.

unsigned long PaUtil_EndBufferProcessing	(	PaUtilBufferProcessor *	bufferProcessor,
		int *	callbackResult
	)

Finish processing a host buffer (or a pair of host buffers in the full-duplex case) for a callback stream.

Parameters

bufferProcessor The buffer processor.

callbackResult On input, indicates a previous callback result, and on exit, the result of the user stream callback, if it is called. On entry callbackResult should contain one of { paContinue, paComplete, or paAbort}. If paComplete is passed, the stream callback will not be called but any audio that was generated by previous stream callbacks will be copied to the output buffer(s). You can check whether the buffer processor's internal buffer is empty by calling PaUtil_IsBufferProcessorOutputEmpty.

If the stream callback is called its result is stored in *callbackResult. If the stream callback returns paComplete or paAbort, all output buffers will be full of valid data - some of which may be zeros to account for data that wasn't generated by the terminating callback.

Returns: The number of frames processed. This usually corresponds to the number of frames specified by the PaUtil_Set*FrameCount functions, except in the paUtilVariableHostBufferSizePartialUsageAllowed buffer size mode when a smaller value may be returned.

References PaUtilChannelDescriptor::data, PaUtilBufferProcessor::hostBufferSizeMode, PaUtilBufferProcessor::hostInputChannels, PaUtilBufferProcessor::hostInputFrameCount, PaUtilBufferProcessor::hostOutputChannels, PaUtilBufferProcessor::hostOutputFrameCount, PaUtilBufferProcessor::inputChannelCount, PaUtilBufferProcessor::outputChannelCount, PA_MIN_, paAbort, paComplete, paContinue, paUtilVariableHostBufferSizePartialUsageAllowed, and PaUtilBufferProcessor::useNonAdaptingProcess.

Referenced by ProcessingThreadProc().

unsigned long PaUtil_GetBufferProcessorInputLatencyFrames ( PaUtilBufferProcessor * bufferProcessor )

Retrieve the input latency of a buffer processor, in frames.

Parameters

bufferProcessor The buffer processor examine.

Returns: The input latency introduced by the buffer processor, in frames.

See Also: PaUtil_GetBufferProcessorOutputLatencyFrames

References PaUtilBufferProcessor::initialFramesInTempInputBuffer.

Referenced by OpenStream().

unsigned long PaUtil_GetBufferProcessorOutputLatencyFrames ( PaUtilBufferProcessor * bufferProcessor )

Retrieve the output latency of a buffer processor, in frames.

Parameters

bufferProcessor The buffer processor examine.

Returns: The output latency introduced by the buffer processor, in frames.

See Also: PaUtil_GetBufferProcessorInputLatencyFrames

References PaUtilBufferProcessor::initialFramesInTempOutputBuffer.

Referenced by OpenStream().

PaError PaUtil_InitializeBufferProcessor	(	PaUtilBufferProcessor *	bufferProcessor,
		int	inputChannelCount,
		PaSampleFormat	userInputSampleFormat,
		PaSampleFormat	hostInputSampleFormat,
		int	outputChannelCount,
		PaSampleFormat	userOutputSampleFormat,
		PaSampleFormat	hostOutputSampleFormat,
		double	sampleRate,
		PaStreamFlags	streamFlags,
		unsigned long	framesPerUserBuffer,
		unsigned long	framesPerHostBuffer,
		PaUtilHostBufferSizeMode	hostBufferSizeMode,
		PaStreamCallback *	streamCallback,
		void *	userData
	)

Initialize a buffer processor's representation stored in a PaUtilBufferProcessor structure. Be sure to call PaUtil_TerminateBufferProcessor after finishing with a buffer processor.

Parameters

bufferProcessor	The buffer processor structure to initialize.
inputChannelCount	The number of input channels as passed to Pa_OpenStream or 0 for an output-only stream.
userInputSampleFormat	Format of user input samples, as passed to Pa_OpenStream. This parameter is ignored for ouput-only streams.
hostInputSampleFormat	Format of host input samples. This parameter is ignored for output-only streams. See note about host buffer interleave below.
outputChannelCount	The number of output channels as passed to Pa_OpenStream or 0 for an input-only stream.
userOutputSampleFormat	Format of user output samples, as passed to Pa_OpenStream. This parameter is ignored for input-only streams.
hostOutputSampleFormat	Format of host output samples. This parameter is ignored for input-only streams. See note about host buffer interleave below.
sampleRate	Sample rate of the stream. The more accurate this is the better - it is used for updating time stamps when adapting buffers.
streamFlags	Stream flags as passed to Pa_OpenStream, this parameter is used for selecting special sample conversion options such as clipping and dithering.
framesPerUserBuffer	Number of frames per user buffer, as requested by the framesPerBuffer parameter to Pa_OpenStream. This parameter may be zero to indicate that the user will accept any (and varying) buffer sizes.
framesPerHostBuffer	Specifies the number of frames per host buffer for the fixed buffer size mode, and the maximum number of frames per host buffer for the bounded host buffer size mode. It is ignored for the other modes.
hostBufferSizeMode	A mode flag indicating the size variability of host buffers that will be passed to the buffer processor. See PaUtilHostBufferSizeMode for further details.
streamCallback	The user stream callback passed to Pa_OpenStream.
userData	The user data field passed to Pa_OpenStream.

Note: The interleave flag is ignored for host buffer formats. Host interleave is determined by the use of different SetInput and SetOutput functions.

Returns: An error code indicating whether the initialization was successful. If the error code is not PaNoError, the buffer processor was not initialized and should not be used.

See Also: Pa_OpenStream, PaUtilHostBufferSizeMode, PaUtil_TerminateBufferProcessor

Referenced by OpenStream().

int PaUtil_IsBufferProcessorOutputEmpty ( PaUtilBufferProcessor * bufferProcessor )

Determine whether any callback generated output remains in the buffer processor's internal buffers. This method may be used to determine when to continue calling PaUtil_EndBufferProcessing() after the callback has returned a callbackResult of paComplete.

Parameters

bufferProcessor The buffer processor.

Returns: Returns non-zero when callback generated output remains in the internal buffer and zero (0) when there internal buffer contains no callback generated data.

References PaUtilBufferProcessor::framesInTempOutputBuffer.

void PaUtil_ResetBufferProcessor ( PaUtilBufferProcessor * bufferProcessor )

Clear any internally buffered data. If you call PaUtil_InitializeBufferProcessor in your OpenStream routine, make sure you call PaUtil_ResetBufferProcessor in your StartStream call.

Parameters

bufferProcessor The buffer processor to reset.

Referenced by PaPulseAudio_StartStreamCb().

void PaUtil_Set2ndInputChannel	(	PaUtilBufferProcessor *	bufferProcessor,
		unsigned int	channel,
		void *	data,
		unsigned int	stride
	)

Use for the second buffer half when the input buffer is split in two halves.

See Also: PaUtil_SetInputChannel

References PaUtilChannelDescriptor::data, PaUtilBufferProcessor::hostInputChannels, and PaUtilChannelDescriptor::stride.

void PaUtil_Set2ndInputFrameCount	(	PaUtilBufferProcessor *	bufferProcessor,
		unsigned long	frameCount
	)

Use for the second buffer half when the input buffer is split in two halves.

See Also: PaUtil_SetInputFrameCount

References PaUtilBufferProcessor::hostInputFrameCount.

void PaUtil_Set2ndInterleavedInputChannels	(	PaUtilBufferProcessor *	bufferProcessor,
		unsigned int	firstChannel,
		void *	data,
		unsigned int	channelCount
	)

Use for the second buffer half when the input buffer is split in two halves.

See Also: PaUtil_SetInterleavedInputChannels

References PaUtilBufferProcessor::bytesPerHostInputSample, PaUtilChannelDescriptor::data, PaUtilBufferProcessor::hostInputChannels, PaUtilBufferProcessor::hostInputIsInterleaved, PaUtilBufferProcessor::inputChannelCount, and PaUtilChannelDescriptor::stride.

void PaUtil_Set2ndInterleavedOutputChannels	(	PaUtilBufferProcessor *	bufferProcessor,
		unsigned int	firstChannel,
		void *	data,
		unsigned int	channelCount
	)

Use for the second buffer half when the output buffer is split in two halves.

See Also: PaUtil_SetInterleavedOutputChannels

References PaUtilBufferProcessor::bytesPerHostOutputSample, PaUtilBufferProcessor::hostOutputIsInterleaved, PaUtilBufferProcessor::outputChannelCount, and PaUtil_Set2ndOutputChannel().

void PaUtil_Set2ndNonInterleavedInputChannel	(	PaUtilBufferProcessor *	bufferProcessor,
		unsigned int	channel,
		void *	data
	)

Use for the second buffer half when the input buffer is split in two halves.

See Also: PaUtil_SetNonInterleavedInputChannel

References PaUtilChannelDescriptor::data, PaUtilBufferProcessor::hostInputChannels, PaUtilBufferProcessor::hostInputIsInterleaved, and PaUtilChannelDescriptor::stride.

void PaUtil_Set2ndNonInterleavedOutputChannel	(	PaUtilBufferProcessor *	bufferProcessor,
		unsigned int	channel,
		void *	data
	)

Use for the second buffer half when the output buffer is split in two halves.

See Also: PaUtil_SetNonInterleavedOutputChannel

References PaUtilBufferProcessor::hostOutputIsInterleaved, and PaUtil_Set2ndOutputChannel().

void PaUtil_Set2ndOutputChannel	(	PaUtilBufferProcessor *	bufferProcessor,
		unsigned int	channel,
		void *	data,
		unsigned int	stride
	)

Use for the second buffer half when the output buffer is split in two halves.

See Also: PaUtil_SetOutputChannel

References PaUtilChannelDescriptor::data, PaUtilBufferProcessor::hostOutputChannels, and PaUtilChannelDescriptor::stride.

Referenced by PaUtil_Set2ndInterleavedOutputChannels(), and PaUtil_Set2ndNonInterleavedOutputChannel().

void PaUtil_Set2ndOutputFrameCount	(	PaUtilBufferProcessor *	bufferProcessor,
		unsigned long	frameCount
	)

Use for the second buffer half when the output buffer is split in two halves.

See Also: PaUtil_SetOutputFrameCount

References PaUtilBufferProcessor::hostOutputFrameCount.

void PaUtil_SetInputChannel	(	PaUtilBufferProcessor *	bufferProcessor,
		unsigned int	channel,
		void *	data,
		unsigned int	stride
	)

Provide the buffer processor with a pointer to a host input channel.

Parameters

bufferProcessor	The buffer processor.
channel	The channel number.
data	The buffer.
stride	The stride from one sample to the next, in samples. For interleaved host buffers, the stride will usually be the same as the number of channels in the buffer.

References PaUtilChannelDescriptor::data, PaUtilBufferProcessor::hostInputChannels, and PaUtilChannelDescriptor::stride.

void PaUtil_SetInputFrameCount	(	PaUtilBufferProcessor *	bufferProcessor,
		unsigned long	frameCount
	)

Set the number of frames in the input host buffer(s) specified by the PaUtil_Set*InputChannel functions.

Parameters

bufferProcessor	The buffer processor.
frameCount	The number of host input frames. A 0 frameCount indicates to use the framesPerHostBuffer value passed to PaUtil_InitializeBufferProcessor.

See Also: PaUtil_SetNoInput, PaUtil_SetInputChannel, PaUtil_SetInterleavedInputChannels, PaUtil_SetNonInterleavedInputChannel

References PaUtilBufferProcessor::framesPerHostBuffer, and PaUtilBufferProcessor::hostInputFrameCount.

Referenced by ProcessingThreadProc().

void PaUtil_SetInterleavedInputChannels	(	PaUtilBufferProcessor *	bufferProcessor,
		unsigned int	firstChannel,
		void *	data,
		unsigned int	channelCount
	)

Provide the buffer processor with a pointer to an number of interleaved host input channels.

Parameters

bufferProcessor	The buffer processor.
firstChannel	The first channel number.
data	The buffer.
channelCount	The number of interleaved channels in the buffer. If channelCount is zero, the number of channels specified to PaUtil_InitializeBufferProcessor will be used.

References PaUtilBufferProcessor::bytesPerHostInputSample, PaUtilChannelDescriptor::data, PaUtilBufferProcessor::hostInputChannels, PaUtilBufferProcessor::hostInputIsInterleaved, PaUtilBufferProcessor::inputChannelCount, and PaUtilChannelDescriptor::stride.

Referenced by ProcessingThreadProc().

void PaUtil_SetInterleavedOutputChannels	(	PaUtilBufferProcessor *	bufferProcessor,
		unsigned int	firstChannel,
		void *	data,
		unsigned int	channelCount
	)

Provide the buffer processor with a pointer to a number of interleaved host output channels.

Parameters

bufferProcessor	The buffer processor.
firstChannel	The first channel number.
data	The buffer.
channelCount	The number of interleaved channels in the buffer. If channelCount is zero, the number of channels specified to PaUtil_InitializeBufferProcessor will be used.

References PaUtilBufferProcessor::bytesPerHostOutputSample, PaUtilBufferProcessor::hostOutputIsInterleaved, PaUtilBufferProcessor::outputChannelCount, and PaUtil_SetOutputChannel().

Referenced by ProcessingThreadProc().

void PaUtil_SetNoInput ( PaUtilBufferProcessor * bufferProcessor )

Indicate that no input is available. This function should be used when priming the output of a full-duplex stream opened with the paPrimeOutputBuffersUsingStreamCallback flag. Note that it is not necessary to call this or any other PaUtil_Set*Input* functions for ouput-only streams.

Parameters

bufferProcessor The buffer processor.

References PaUtilChannelDescriptor::data, PaUtilBufferProcessor::hostInputChannels, and PaUtilBufferProcessor::inputChannelCount.

void PaUtil_SetNonInterleavedInputChannel	(	PaUtilBufferProcessor *	bufferProcessor,
		unsigned int	channel,
		void *	data
	)

Provide the buffer processor with a pointer to one non-interleaved host output channel.

Parameters

bufferProcessor	The buffer processor.
channel	The channel number.
data	The buffer.

References PaUtilChannelDescriptor::data, PaUtilBufferProcessor::hostInputChannels, PaUtilBufferProcessor::hostInputIsInterleaved, and PaUtilChannelDescriptor::stride.

void PaUtil_SetNonInterleavedOutputChannel	(	PaUtilBufferProcessor *	bufferProcessor,
		unsigned int	channel,
		void *	data
	)

Provide the buffer processor with a pointer to one non-interleaved host output channel.

Parameters

bufferProcessor	The buffer processor.
channel	The channel number.
data	The buffer.

References PaUtilBufferProcessor::hostOutputIsInterleaved, and PaUtil_SetOutputChannel().

void PaUtil_SetNoOutput ( PaUtilBufferProcessor * bufferProcessor )

Indicate that the output will be discarded. This function should be used when implementing the paNeverDropInput mode for full duplex streams.

Parameters

bufferProcessor The buffer processor.

References PaUtilChannelDescriptor::data, PaUtilBufferProcessor::hostOutputChannels, and PaUtilBufferProcessor::outputChannelCount.

void PaUtil_SetOutputChannel	(	PaUtilBufferProcessor *	bufferProcessor,
		unsigned int	channel,
		void *	data,
		unsigned int	stride
	)

Provide the buffer processor with a pointer to a host output channel.

Parameters

bufferProcessor	The buffer processor.
channel	The channel number.
data	The buffer.
stride	The stride from one sample to the next, in samples. For interleaved host buffers, the stride will usually be the same as the number of channels in the buffer.

References PaUtilChannelDescriptor::data, PaUtilBufferProcessor::hostOutputChannels, and PaUtilChannelDescriptor::stride.

Referenced by PaUtil_SetInterleavedOutputChannels(), and PaUtil_SetNonInterleavedOutputChannel().

void PaUtil_SetOutputFrameCount	(	PaUtilBufferProcessor *	bufferProcessor,
		unsigned long	frameCount
	)

Set the number of frames in the output host buffer(s) specified by the PaUtil_Set*OutputChannel functions.

Parameters

bufferProcessor	The buffer processor.
frameCount	The number of host output frames. A 0 frameCount indicates to use the framesPerHostBuffer value passed to PaUtil_InitializeBufferProcessor.