pa_process.h File Reference

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"

Go to the source code of this file.

Data Structures

struct  PaUtilChannelDescriptor
 An auxilliary 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...

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_GetBufferProcessorInputLatency (PaUtilBufferProcessor *bufferProcessor)
unsigned long PaUtil_GetBufferProcessorOutputLatency (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 neccesary 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:

  1. Call PaUtil_BeginBufferProcessing
  2. 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 accross 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.
  3. 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 accross 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.
  4. 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.

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


Enumeration Type Documentation

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.

FIXME:

Todo:
time info currentTime not implemented

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

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 
)
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 acount 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, exept 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.

unsigned long PaUtil_GetBufferProcessorInputLatency ( PaUtilBufferProcessor bufferProcessor  ) 

Retrieve the input latency of a buffer processor.

Parameters:
bufferProcessor The buffer processor examine.
Returns:
The input latency introduced by the buffer processor, in frames.
See also:
PaUtil_GetBufferProcessorOutputLatency

References PaUtilBufferProcessor::initialFramesInTempInputBuffer.

unsigned long PaUtil_GetBufferProcessorOutputLatency ( PaUtilBufferProcessor bufferProcessor  ) 

Retrieve the output latency of a buffer processor.

Parameters:
bufferProcessor The buffer processor examine.
Returns:
The output latency introduced by the buffer processor, in frames.
See also:
PaUtil_GetBufferProcessorInputLatency

References PaUtilBufferProcessor::initialFramesInTempOutputBuffer.

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

References PaUtilBufferProcessor::bytesPerHostInputSample, PaUtilBufferProcessor::bytesPerHostOutputSample, PaUtilBufferProcessor::bytesPerUserInputSample, PaUtilBufferProcessor::bytesPerUserOutputSample, PaUtilBufferProcessor::ditherGenerator, PaUtilBufferProcessor::framesInTempInputBuffer, PaUtilBufferProcessor::framesInTempOutputBuffer, PaUtilBufferProcessor::framesPerHostBuffer, PaUtilBufferProcessor::framesPerTempBuffer, PaUtilBufferProcessor::framesPerUserBuffer, PaUtilBufferProcessor::hostBufferSizeMode, PaUtilBufferProcessor::hostInputChannels, PaUtilBufferProcessor::hostOutputChannels, PaUtilBufferProcessor::initialFramesInTempInputBuffer, PaUtilBufferProcessor::initialFramesInTempOutputBuffer, PaUtilBufferProcessor::inputChannelCount, PaUtilBufferProcessor::inputConverter, PaUtilBufferProcessor::inputZeroer, PaUtilBufferProcessor::outputChannelCount, PaUtilBufferProcessor::outputConverter, PaUtilBufferProcessor::outputZeroer, PA_FRAMES_PER_TEMP_BUFFER_WHEN_HOST_BUFFER_SIZE_IS_UNKNOWN_, Pa_GetSampleSize(), paFramesPerBufferUnspecified, paInsufficientMemory, paInvalidFlag, paNeverDropInput, paNoError, paNonInterleaved, PaUtil_AllocateMemory(), PaUtil_FreeMemory(), PaUtil_InitializeTriangularDitherState(), PaUtil_SelectConverter(), PaUtil_SelectZeroer(), paUtilBoundedHostBufferSize, paUtilFixedHostBufferSize, PaUtilBufferProcessor::samplePeriod, PaUtilBufferProcessor::streamCallback, PaUtilBufferProcessor::tempInputBuffer, PaUtilBufferProcessor::tempInputBufferPtrs, PaUtilBufferProcessor::tempOutputBuffer, PaUtilBufferProcessor::tempOutputBufferPtrs, PaUtilBufferProcessor::useNonAdaptingProcess, PaUtilBufferProcessor::userData, PaUtilBufferProcessor::userInputIsInterleaved, and PaUtilBufferProcessor::userOutputIsInterleaved.

int PaUtil_IsBufferProcessorOutputEmpty ( PaUtilBufferProcessor bufferProcessor  ) 

Determine whether any callback generated output remains in the bufffer 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  ) 
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 
)
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::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, 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 PaUtil_Set2ndOutputChannel().

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

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::inputChannelCount, and PaUtilChannelDescriptor::stride.

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::outputChannelCount, and PaUtil_SetOutputChannel().

void PaUtil_SetNoInput ( PaUtilBufferProcessor bufferProcessor  ) 

Indicate that no input is avalable. 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 othe 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, 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 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.
See also:
PaUtil_SetOutputChannel, PaUtil_SetInterleavedOutputChannels, PaUtil_SetNonInterleavedOutputChannel

References PaUtilBufferProcessor::framesPerHostBuffer, and PaUtilBufferProcessor::hostOutputFrameCount.

void PaUtil_TerminateBufferProcessor ( PaUtilBufferProcessor bufferProcessor  ) 

Terminate a buffer processor's representation. Deallocates any temporary buffers allocated by PaUtil_InitializeBufferProcessor.

Parameters:
bufferProcessor The buffer processor structure to terminate.
See also:
PaUtil_InitializeBufferProcessor.

References PaUtilBufferProcessor::hostInputChannels, PaUtilBufferProcessor::hostOutputChannels, PaUtil_FreeMemory(), PaUtilBufferProcessor::tempInputBuffer, PaUtilBufferProcessor::tempInputBufferPtrs, PaUtilBufferProcessor::tempOutputBuffer, and PaUtilBufferProcessor::tempOutputBufferPtrs.

unsigned long PaUtil_ZeroOutput ( PaUtilBufferProcessor bufferProcessor,
unsigned long  frameCount 
)

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