4 * $Id: portaudio.h 1745 2011-08-25 17:44:01Z rossb $
5 * PortAudio Portable Real-Time Audio Library
6 * PortAudio API Header File
7 * Latest version available at: http://www.portaudio.com/
9 * Copyright (c) 1999-2002 Ross Bencina and Phil Burk
11 * Permission is hereby granted, free of charge, to any person obtaining
12 * a copy of this software and associated documentation files
13 * (the "Software"), to deal in the Software without restriction,
14 * including without limitation the rights to use, copy, modify, merge,
15 * publish, distribute, sublicense, and/or sell copies of the Software,
16 * and to permit persons to whom the Software is furnished to do so,
17 * subject to the following conditions:
19 * The above copyright notice and this permission notice shall be
20 * included in all copies or substantial portions of the Software.
22 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
23 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
24 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
25 * IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR
26 * ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF
27 * CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
28 * WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
32 * The text above constitutes the entire PortAudio license; however,
33 * the PortAudio community also makes the following non-binding requests:
35 * Any person wishing to distribute modifications to the Software is
36 * requested to send the modifications to the original developer so that
37 * they can be incorporated into the canonical version. It is also
38 * requested that these non-binding requests be included along with the
43 @ingroup public_header
44 @brief The portable PortAudio API.
51 #endif /* __cplusplus */
54 /** Retrieve the release number of the currently running PortAudio build,
57 int Pa_GetVersion( void );
60 /** Retrieve a textual description of the current PortAudio build,
61 eg "PortAudio V19-devel 13 October 2002".
63 const char* Pa_GetVersionText( void );
66 /** Error codes returned by PortAudio functions.
67 Note that with the exception of paNoError, all PaErrorCodes are negative.
71 typedef enum PaErrorCode
75 paNotInitialized = -10000,
76 paUnanticipatedHostError,
77 paInvalidChannelCount,
81 paSampleFormatNotSupported,
82 paBadIODeviceCombination,
91 paIncompatibleHostApiSpecificStreamInfo,
98 paCanNotReadFromACallbackStream,
99 paCanNotWriteToACallbackStream,
100 paCanNotReadFromAnOutputOnlyStream,
101 paCanNotWriteToAnInputOnlyStream,
102 paIncompatibleStreamHostApi,
107 /** Translate the supplied PortAudio error code into a human readable
110 const char *Pa_GetErrorText( PaError errorCode );
113 /** Library initialization function - call this before using PortAudio.
114 This function initializes internal data structures and prepares underlying
115 host APIs for use. With the exception of Pa_GetVersion(), Pa_GetVersionText(),
116 and Pa_GetErrorText(), this function MUST be called before using any other
117 PortAudio API functions.
119 If Pa_Initialize() is called multiple times, each successful
120 call must be matched with a corresponding call to Pa_Terminate().
121 Pairs of calls to Pa_Initialize()/Pa_Terminate() may overlap, and are not
122 required to be fully nested.
124 Note that if Pa_Initialize() returns an error code, Pa_Terminate() should
127 @return paNoError if successful, otherwise an error code indicating the cause
132 PaError Pa_Initialize( void );
135 /** Library termination function - call this when finished using PortAudio.
136 This function deallocates all resources allocated by PortAudio since it was
137 initialized by a call to Pa_Initialize(). In cases where Pa_Initialise() has
138 been called multiple times, each call must be matched with a corresponding call
139 to Pa_Terminate(). The final matching call to Pa_Terminate() will automatically
140 close any PortAudio streams that are still open.
142 Pa_Terminate() MUST be called before exiting a program which uses PortAudio.
143 Failure to do so may result in serious resource leaks, such as audio devices
144 not being available until the next reboot.
146 @return paNoError if successful, otherwise an error code indicating the cause
151 PaError Pa_Terminate( void );
155 /** The type used to refer to audio devices. Values of this type usually
156 range from 0 to (Pa_GetDeviceCount()-1), and may also take on the PaNoDevice
157 and paUseHostApiSpecificDeviceSpecification values.
159 @see Pa_GetDeviceCount, paNoDevice, paUseHostApiSpecificDeviceSpecification
161 typedef int PaDeviceIndex;
164 /** A special PaDeviceIndex value indicating that no device is available,
169 #define paNoDevice ((PaDeviceIndex)-1)
172 /** A special PaDeviceIndex value indicating that the device(s) to be used
173 are specified in the host api specific stream info structure.
177 #define paUseHostApiSpecificDeviceSpecification ((PaDeviceIndex)-2)
180 /* Host API enumeration mechanism */
182 /** The type used to enumerate to host APIs at runtime. Values of this type
183 range from 0 to (Pa_GetHostApiCount()-1).
185 @see Pa_GetHostApiCount
187 typedef int PaHostApiIndex;
190 /** Retrieve the number of available host APIs. Even if a host API is
191 available it may have no devices available.
193 @return A non-negative value indicating the number of available host APIs
194 or, a PaErrorCode (which are always negative) if PortAudio is not initialized
195 or an error is encountered.
199 PaHostApiIndex Pa_GetHostApiCount( void );
202 /** Retrieve the index of the default host API. The default host API will be
203 the lowest common denominator host API on the current platform and is
204 unlikely to provide the best performance.
206 @return A non-negative value ranging from 0 to (Pa_GetHostApiCount()-1)
207 indicating the default host API index or, a PaErrorCode (which are always
208 negative) if PortAudio is not initialized or an error is encountered.
210 PaHostApiIndex Pa_GetDefaultHostApi( void );
213 /** Unchanging unique identifiers for each supported host API. This type
214 is used in the PaHostApiInfo structure. The values are guaranteed to be
215 unique and to never change, thus allowing code to be written that
216 conditionally uses host API specific extensions.
218 New type ids will be allocated when support for a host API reaches
219 "public alpha" status, prior to that developers should use the
220 paInDevelopment type id.
224 typedef enum PaHostApiTypeId
226 paInDevelopment=0, /* use while developing support for a new host API */
243 /** A structure containing information about a particular host API. */
245 typedef struct PaHostApiInfo
247 /** this is struct version 1 */
249 /** The well known unique identifier of this host API @see PaHostApiTypeId */
250 PaHostApiTypeId type;
251 /** A textual description of the host API for display on user interfaces. */
254 /** The number of devices belonging to this host API. This field may be
255 used in conjunction with Pa_HostApiDeviceIndexToDeviceIndex() to enumerate
256 all devices for this host API.
257 @see Pa_HostApiDeviceIndexToDeviceIndex
261 /** The default input device for this host API. The value will be a
262 device index ranging from 0 to (Pa_GetDeviceCount()-1), or paNoDevice
263 if no default input device is available.
265 PaDeviceIndex defaultInputDevice;
267 /** The default output device for this host API. The value will be a
268 device index ranging from 0 to (Pa_GetDeviceCount()-1), or paNoDevice
269 if no default output device is available.
271 PaDeviceIndex defaultOutputDevice;
276 /** Retrieve a pointer to a structure containing information about a specific
279 @param hostApi A valid host API index ranging from 0 to (Pa_GetHostApiCount()-1)
281 @return A pointer to an immutable PaHostApiInfo structure describing
282 a specific host API. If the hostApi parameter is out of range or an error
283 is encountered, the function returns NULL.
285 The returned structure is owned by the PortAudio implementation and must not
286 be manipulated or freed. The pointer is only guaranteed to be valid between
287 calls to Pa_Initialize() and Pa_Terminate().
289 const PaHostApiInfo * Pa_GetHostApiInfo( PaHostApiIndex hostApi );
292 /** Convert a static host API unique identifier, into a runtime
295 @param type A unique host API identifier belonging to the PaHostApiTypeId
298 @return A valid PaHostApiIndex ranging from 0 to (Pa_GetHostApiCount()-1) or,
299 a PaErrorCode (which are always negative) if PortAudio is not initialized
300 or an error is encountered.
302 The paHostApiNotFound error code indicates that the host API specified by the
303 type parameter is not available.
307 PaHostApiIndex Pa_HostApiTypeIdToHostApiIndex( PaHostApiTypeId type );
310 /** Convert a host-API-specific device index to standard PortAudio device index.
311 This function may be used in conjunction with the deviceCount field of
312 PaHostApiInfo to enumerate all devices for the specified host API.
314 @param hostApi A valid host API index ranging from 0 to (Pa_GetHostApiCount()-1)
316 @param hostApiDeviceIndex A valid per-host device index in the range
317 0 to (Pa_GetHostApiInfo(hostApi)->deviceCount-1)
319 @return A non-negative PaDeviceIndex ranging from 0 to (Pa_GetDeviceCount()-1)
320 or, a PaErrorCode (which are always negative) if PortAudio is not initialized
321 or an error is encountered.
323 A paInvalidHostApi error code indicates that the host API index specified by
324 the hostApi parameter is out of range.
326 A paInvalidDevice error code indicates that the hostApiDeviceIndex parameter
331 PaDeviceIndex Pa_HostApiDeviceIndexToDeviceIndex( PaHostApiIndex hostApi,
332 int hostApiDeviceIndex );
336 /** Structure used to return information about a host error condition.
338 typedef struct PaHostErrorInfo{
339 PaHostApiTypeId hostApiType; /**< the host API which returned the error code */
340 long errorCode; /**< the error code returned */
341 const char *errorText; /**< a textual description of the error if available, otherwise a zero-length string */
345 /** Return information about the last host error encountered. The error
346 information returned by Pa_GetLastHostErrorInfo() will never be modified
347 asynchronously by errors occurring in other PortAudio owned threads
348 (such as the thread that manages the stream callback.)
350 This function is provided as a last resort, primarily to enhance debugging
351 by providing clients with access to all available error information.
353 @return A pointer to an immutable structure constraining information about
354 the host error. The values in this structure will only be valid if a
355 PortAudio function has previously returned the paUnanticipatedHostError
358 const PaHostErrorInfo* Pa_GetLastHostErrorInfo( void );
362 /* Device enumeration and capabilities */
364 /** Retrieve the number of available devices. The number of available devices
367 @return A non-negative value indicating the number of available devices or,
368 a PaErrorCode (which are always negative) if PortAudio is not initialized
369 or an error is encountered.
371 PaDeviceIndex Pa_GetDeviceCount( void );
374 /** Retrieve the index of the default input device. The result can be
375 used in the inputDevice parameter to Pa_OpenStream().
377 @return The default input device index for the default host API, or paNoDevice
378 if no default input device is available or an error was encountered.
380 PaDeviceIndex Pa_GetDefaultInputDevice( void );
383 /** Retrieve the index of the default output device. The result can be
384 used in the outputDevice parameter to Pa_OpenStream().
386 @return The default output device index for the default host API, or paNoDevice
387 if no default output device is available or an error was encountered.
390 On the PC, the user can specify a default device by
391 setting an environment variable. For example, to use device #1.
393 set PA_RECOMMENDED_OUTPUT_DEVICE=1
395 The user should first determine the available device ids by using
396 the supplied application "pa_devs".
398 PaDeviceIndex Pa_GetDefaultOutputDevice( void );
401 /** The type used to represent monotonic time in seconds. PaTime is
402 used for the fields of the PaStreamCallbackTimeInfo argument to the
403 PaStreamCallback and as the result of Pa_GetStreamTime().
405 PaTime values have unspecified origin.
407 @see PaStreamCallback, PaStreamCallbackTimeInfo, Pa_GetStreamTime
409 typedef double PaTime;
412 /** A type used to specify one or more sample formats. Each value indicates
413 a possible format for sound data passed to and from the stream callback,
414 Pa_ReadStream and Pa_WriteStream.
416 The standard formats paFloat32, paInt16, paInt32, paInt24, paInt8
417 and aUInt8 are usually implemented by all implementations.
419 The floating point representation (paFloat32) uses +1.0 and -1.0 as the
420 maximum and minimum respectively.
422 paUInt8 is an unsigned 8 bit format where 128 is considered "ground"
424 The paNonInterleaved flag indicates that audio data is passed as an array
425 of pointers to separate buffers, one buffer for each channel. Usually,
426 when this flag is not used, audio data is passed as a single buffer with
427 all channels interleaved.
429 @see Pa_OpenStream, Pa_OpenDefaultStream, PaDeviceInfo
430 @see paFloat32, paInt16, paInt32, paInt24, paInt8
431 @see paUInt8, paCustomFormat, paNonInterleaved
433 typedef unsigned long PaSampleFormat;
436 #define paFloat32 ((PaSampleFormat) 0x00000001) /**< @see PaSampleFormat */
437 #define paInt32 ((PaSampleFormat) 0x00000002) /**< @see PaSampleFormat */
438 #define paInt24 ((PaSampleFormat) 0x00000004) /**< Packed 24 bit format. @see PaSampleFormat */
439 #define paInt16 ((PaSampleFormat) 0x00000008) /**< @see PaSampleFormat */
440 #define paInt8 ((PaSampleFormat) 0x00000010) /**< @see PaSampleFormat */
441 #define paUInt8 ((PaSampleFormat) 0x00000020) /**< @see PaSampleFormat */
442 #define paCustomFormat ((PaSampleFormat) 0x00010000) /**< @see PaSampleFormat */
444 #define paNonInterleaved ((PaSampleFormat) 0x80000000) /**< @see PaSampleFormat */
446 /** A structure providing information and capabilities of PortAudio devices.
447 Devices may support input, output or both input and output.
449 typedef struct PaDeviceInfo
451 int structVersion; /* this is struct version 2 */
453 PaHostApiIndex hostApi; /**< note this is a host API index, not a type id*/
455 int maxInputChannels;
456 int maxOutputChannels;
458 /** Default latency values for interactive performance. */
459 PaTime defaultLowInputLatency;
460 PaTime defaultLowOutputLatency;
461 /** Default latency values for robust non-interactive applications (eg. playing sound files). */
462 PaTime defaultHighInputLatency;
463 PaTime defaultHighOutputLatency;
465 double defaultSampleRate;
469 /** Retrieve a pointer to a PaDeviceInfo structure containing information
470 about the specified device.
471 @return A pointer to an immutable PaDeviceInfo structure. If the device
472 parameter is out of range the function returns NULL.
474 @param device A valid device index in the range 0 to (Pa_GetDeviceCount()-1)
476 @note PortAudio manages the memory referenced by the returned pointer,
477 the client must not manipulate or free the memory. The pointer is only
478 guaranteed to be valid between calls to Pa_Initialize() and Pa_Terminate().
480 @see PaDeviceInfo, PaDeviceIndex
482 const PaDeviceInfo* Pa_GetDeviceInfo( PaDeviceIndex device );
485 /** Parameters for one direction (input or output) of a stream.
487 typedef struct PaStreamParameters
489 /** A valid device index in the range 0 to (Pa_GetDeviceCount()-1)
490 specifying the device to be used or the special constant
491 paUseHostApiSpecificDeviceSpecification which indicates that the actual
492 device(s) to use are specified in hostApiSpecificStreamInfo.
493 This field must not be set to paNoDevice.
495 PaDeviceIndex device;
497 /** The number of channels of sound to be delivered to the
498 stream callback or accessed by Pa_ReadStream() or Pa_WriteStream().
499 It can range from 1 to the value of maxInputChannels in the
500 PaDeviceInfo record for the device specified by the device parameter.
504 /** The sample format of the buffer provided to the stream callback,
505 a_ReadStream() or Pa_WriteStream(). It may be any of the formats described
506 by the PaSampleFormat enumeration.
508 PaSampleFormat sampleFormat;
510 /** The desired latency in seconds. Where practical, implementations should
511 configure their latency based on these parameters, otherwise they may
512 choose the closest viable latency instead. Unless the suggested latency
513 is greater than the absolute upper limit for the device implementations
514 should round the suggestedLatency up to the next practical value - ie to
515 provide an equal or higher latency than suggestedLatency wherever possible.
516 Actual latency values for an open stream may be retrieved using the
517 inputLatency and outputLatency fields of the PaStreamInfo structure
518 returned by Pa_GetStreamInfo().
519 @see default*Latency in PaDeviceInfo, *Latency in PaStreamInfo
521 PaTime suggestedLatency;
523 /** An optional pointer to a host api specific data structure
524 containing additional information for device setup and/or stream processing.
525 hostApiSpecificStreamInfo is never required for correct operation,
526 if not used it should be set to NULL.
528 void *hostApiSpecificStreamInfo;
530 } PaStreamParameters;
533 /** Return code for Pa_IsFormatSupported indicating success. */
534 #define paFormatIsSupported (0)
536 /** Determine whether it would be possible to open a stream with the specified
539 @param inputParameters A structure that describes the input parameters used to
540 open a stream. The suggestedLatency field is ignored. See PaStreamParameters
541 for a description of these parameters. inputParameters must be NULL for
544 @param outputParameters A structure that describes the output parameters used
545 to open a stream. The suggestedLatency field is ignored. See PaStreamParameters
546 for a description of these parameters. outputParameters must be NULL for
549 @param sampleRate The required sampleRate. For full-duplex streams it is the
550 sample rate for both input and output
552 @return Returns 0 if the format is supported, and an error code indicating why
553 the format is not supported otherwise. The constant paFormatIsSupported is
554 provided to compare with the return value for success.
556 @see paFormatIsSupported, PaStreamParameters
558 PaError Pa_IsFormatSupported( const PaStreamParameters *inputParameters,
559 const PaStreamParameters *outputParameters,
564 /* Streaming types and functions */
568 A single PaStream can provide multiple channels of real-time
569 streaming audio input and output to a client application. A stream
570 provides access to audio hardware represented by one or more
571 PaDevices. Depending on the underlying Host API, it may be possible
572 to open multiple streams using the same device, however this behavior
573 is implementation defined. Portable applications should assume that
574 a PaDevice may be simultaneously used by at most one PaStream.
576 Pointers to PaStream objects are passed between PortAudio functions that
579 @see Pa_OpenStream, Pa_OpenDefaultStream, Pa_OpenDefaultStream, Pa_CloseStream,
580 Pa_StartStream, Pa_StopStream, Pa_AbortStream, Pa_IsStreamActive,
581 Pa_GetStreamTime, Pa_GetStreamCpuLoad
584 typedef void PaStream;
587 /** Can be passed as the framesPerBuffer parameter to Pa_OpenStream()
588 or Pa_OpenDefaultStream() to indicate that the stream callback will
589 accept buffers of any size.
591 #define paFramesPerBufferUnspecified (0)
594 /** Flags used to control the behavior of a stream. They are passed as
595 parameters to Pa_OpenStream or Pa_OpenDefaultStream. Multiple flags may be
598 @see Pa_OpenStream, Pa_OpenDefaultStream
599 @see paNoFlag, paClipOff, paDitherOff, paNeverDropInput,
600 paPrimeOutputBuffersUsingStreamCallback, paPlatformSpecificFlags
602 typedef unsigned long PaStreamFlags;
604 /** @see PaStreamFlags */
605 #define paNoFlag ((PaStreamFlags) 0)
607 /** Disable default clipping of out of range samples.
610 #define paClipOff ((PaStreamFlags) 0x00000001)
612 /** Disable default dithering.
615 #define paDitherOff ((PaStreamFlags) 0x00000002)
617 /** Flag requests that where possible a full duplex stream will not discard
618 overflowed input samples without calling the stream callback. This flag is
619 only valid for full duplex callback streams and only when used in combination
620 with the paFramesPerBufferUnspecified (0) framesPerBuffer parameter. Using
621 this flag incorrectly results in a paInvalidFlag error being returned from
622 Pa_OpenStream and Pa_OpenDefaultStream.
624 @see PaStreamFlags, paFramesPerBufferUnspecified
626 #define paNeverDropInput ((PaStreamFlags) 0x00000004)
628 /** Call the stream callback to fill initial output buffers, rather than the
629 default behavior of priming the buffers with zeros (silence). This flag has
630 no effect for input-only and blocking read/write streams.
634 #define paPrimeOutputBuffersUsingStreamCallback ((PaStreamFlags) 0x00000008)
636 /** A mask specifying the platform specific bits.
639 #define paPlatformSpecificFlags ((PaStreamFlags)0xFFFF0000)
642 Timing information for the buffers passed to the stream callback.
644 Time values are expressed in seconds and are synchronised with the time base used by Pa_GetStreamTime() for the associated stream.
646 @see PaStreamCallback, Pa_GetStreamTime
648 typedef struct PaStreamCallbackTimeInfo{
649 PaTime inputBufferAdcTime; /**< The time when the first sample of the input buffer was captured at the ADC input */
650 PaTime currentTime; /**< The time when the stream callback was invoked */
651 PaTime outputBufferDacTime; /**< The time when the first sample of the output buffer will output the DAC */
652 } PaStreamCallbackTimeInfo;
656 Flag bit constants for the statusFlags to PaStreamCallback.
658 @see paInputUnderflow, paInputOverflow, paOutputUnderflow, paOutputOverflow,
661 typedef unsigned long PaStreamCallbackFlags;
663 /** In a stream opened with paFramesPerBufferUnspecified, indicates that
664 input data is all silence (zeros) because no real data is available. In a
665 stream opened without paFramesPerBufferUnspecified, it indicates that one or
666 more zero samples have been inserted into the input buffer to compensate
667 for an input underflow.
668 @see PaStreamCallbackFlags
670 #define paInputUnderflow ((PaStreamCallbackFlags) 0x00000001)
672 /** In a stream opened with paFramesPerBufferUnspecified, indicates that data
673 prior to the first sample of the input buffer was discarded due to an
674 overflow, possibly because the stream callback is using too much CPU time.
675 Otherwise indicates that data prior to one or more samples in the
676 input buffer was discarded.
677 @see PaStreamCallbackFlags
679 #define paInputOverflow ((PaStreamCallbackFlags) 0x00000002)
681 /** Indicates that output data (or a gap) was inserted, possibly because the
682 stream callback is using too much CPU time.
683 @see PaStreamCallbackFlags
685 #define paOutputUnderflow ((PaStreamCallbackFlags) 0x00000004)
687 /** Indicates that output data will be discarded because no room is available.
688 @see PaStreamCallbackFlags
690 #define paOutputOverflow ((PaStreamCallbackFlags) 0x00000008)
692 /** Some of all of the output data will be used to prime the stream, input
694 @see PaStreamCallbackFlags
696 #define paPrimingOutput ((PaStreamCallbackFlags) 0x00000010)
699 Allowable return values for the PaStreamCallback.
700 @see PaStreamCallback
702 typedef enum PaStreamCallbackResult
704 paContinue=0, /**< Signal that the stream should continue invoking the callback and processing audio. */
705 paComplete=1, /**< Signal that the stream should stop invoking the callback and finish once all output samples have played. */
706 paAbort=2 /**< Signal that the stream should stop invoking the callback and finish as soon as possible. */
707 } PaStreamCallbackResult;
711 Functions of type PaStreamCallback are implemented by PortAudio clients.
712 They consume, process or generate audio in response to requests from an
713 active PortAudio stream.
715 When a stream is running, PortAudio calls the stream callback periodically.
716 The callback function is responsible for processing buffers of audio samples
717 passed via the input and output parameters.
719 The PortAudio stream callback runs at very high or real-time priority.
720 It is required to consistently meet its time deadlines. Do not allocate
721 memory, access the file system, call library functions or call other functions
722 from the stream callback that may block or take an unpredictable amount of
725 In order for a stream to maintain glitch-free operation the callback
726 must consume and return audio data faster than it is recorded and/or
727 played. PortAudio anticipates that each callback invocation may execute for
728 a duration approaching the duration of frameCount audio frames at the stream
729 sample rate. It is reasonable to expect to be able to utilise 70% or more of
730 the available CPU time in the PortAudio callback. However, due to buffer size
731 adaption and other factors, not all host APIs are able to guarantee audio
732 stability under heavy CPU load with arbitrary fixed callback buffer sizes.
733 When high callback CPU utilisation is required the most robust behavior
734 can be achieved by using paFramesPerBufferUnspecified as the
735 Pa_OpenStream() framesPerBuffer parameter.
737 @param input and @param output are either arrays of interleaved samples or;
738 if non-interleaved samples were requested using the paNonInterleaved sample
739 format flag, an array of buffer pointers, one non-interleaved buffer for
742 The format, packing and number of channels used by the buffers are
743 determined by parameters to Pa_OpenStream().
745 @param frameCount The number of sample frames to be processed by
748 @param timeInfo Timestamps indicating the ADC capture time of the first sample
749 in the input buffer, the DAC output time of the first sample in the output buffer
750 and the time the callback was invoked.
751 See PaStreamCallbackTimeInfo and Pa_GetStreamTime()
753 @param statusFlags Flags indicating whether input and/or output buffers
754 have been inserted or will be dropped to overcome underflow or overflow
757 @param userData The value of a user supplied pointer passed to
758 Pa_OpenStream() intended for storing synthesis data etc.
761 The stream callback should return one of the values in the
762 ::PaStreamCallbackResult enumeration. To ensure that the callback continues
763 to be called, it should return paContinue (0). Either paComplete or paAbort
764 can be returned to finish stream processing, after either of these values is
765 returned the callback will not be called again. If paAbort is returned the
766 stream will finish as soon as possible. If paComplete is returned, the stream
767 will continue until all buffers generated by the callback have been played.
768 This may be useful in applications such as soundfile players where a specific
769 duration of output is required. However, it is not necessary to utilize this
770 mechanism as Pa_StopStream(), Pa_AbortStream() or Pa_CloseStream() can also
771 be used to stop the stream. The callback must always fill the entire output
772 buffer irrespective of its return value.
774 @see Pa_OpenStream, Pa_OpenDefaultStream
776 @note With the exception of Pa_GetStreamCpuLoad() it is not permissible to call
777 PortAudio API functions from within the stream callback.
779 typedef int PaStreamCallback(
780 const void *input, void *output,
781 unsigned long frameCount,
782 const PaStreamCallbackTimeInfo* timeInfo,
783 PaStreamCallbackFlags statusFlags,
787 /** Opens a stream for either input, output or both.
789 @param stream The address of a PaStream pointer which will receive
790 a pointer to the newly opened stream.
792 @param inputParameters A structure that describes the input parameters used by
793 the opened stream. See PaStreamParameters for a description of these parameters.
794 inputParameters must be NULL for output-only streams.
796 @param outputParameters A structure that describes the output parameters used by
797 the opened stream. See PaStreamParameters for a description of these parameters.
798 outputParameters must be NULL for input-only streams.
800 @param sampleRate The desired sampleRate. For full-duplex streams it is the
801 sample rate for both input and output
803 @param framesPerBuffer The number of frames passed to the stream callback
804 function, or the preferred block granularity for a blocking read/write stream.
805 The special value paFramesPerBufferUnspecified (0) may be used to request that
806 the stream callback will receive an optimal (and possibly varying) number of
807 frames based on host requirements and the requested latency settings.
808 Note: With some host APIs, the use of non-zero framesPerBuffer for a callback
809 stream may introduce an additional layer of buffering which could introduce
810 additional latency. PortAudio guarantees that the additional latency
811 will be kept to the theoretical minimum however, it is strongly recommended
812 that a non-zero framesPerBuffer value only be used when your algorithm
813 requires a fixed number of frames per stream callback.
815 @param streamFlags Flags which modify the behavior of the streaming process.
816 This parameter may contain a combination of flags ORed together. Some flags may
817 only be relevant to certain buffer formats.
819 @param streamCallback A pointer to a client supplied function that is responsible
820 for processing and filling input and output buffers. If this parameter is NULL
821 the stream will be opened in 'blocking read/write' mode. In blocking mode,
822 the client can receive sample data using Pa_ReadStream and write sample data
823 using Pa_WriteStream, the number of samples that may be read or written
824 without blocking is returned by Pa_GetStreamReadAvailable and
825 Pa_GetStreamWriteAvailable respectively.
827 @param userData A client supplied pointer which is passed to the stream callback
828 function. It could for example, contain a pointer to instance data necessary
829 for processing the audio buffers. This parameter is ignored if streamCallback
833 Upon success Pa_OpenStream() returns paNoError and places a pointer to a
834 valid PaStream in the stream argument. The stream is inactive (stopped).
835 If a call to Pa_OpenStream() fails, a non-zero error code is returned (see
836 PaError for possible error codes) and the value of stream is invalid.
838 @see PaStreamParameters, PaStreamCallback, Pa_ReadStream, Pa_WriteStream,
839 Pa_GetStreamReadAvailable, Pa_GetStreamWriteAvailable
841 PaError Pa_OpenStream( PaStream** stream,
842 const PaStreamParameters *inputParameters,
843 const PaStreamParameters *outputParameters,
845 unsigned long framesPerBuffer,
846 PaStreamFlags streamFlags,
847 PaStreamCallback *streamCallback,
851 /** A simplified version of Pa_OpenStream() that opens the default input
852 and/or output devices.
854 @param stream The address of a PaStream pointer which will receive
855 a pointer to the newly opened stream.
857 @param numInputChannels The number of channels of sound that will be supplied
858 to the stream callback or returned by Pa_ReadStream. It can range from 1 to
859 the value of maxInputChannels in the PaDeviceInfo record for the default input
860 device. If 0 the stream is opened as an output-only stream.
862 @param numOutputChannels The number of channels of sound to be delivered to the
863 stream callback or passed to Pa_WriteStream. It can range from 1 to the value
864 of maxOutputChannels in the PaDeviceInfo record for the default output device.
865 If 0 the stream is opened as an output-only stream.
867 @param sampleFormat The sample format of both the input and output buffers
868 provided to the callback or passed to and from Pa_ReadStream and Pa_WriteStream.
869 sampleFormat may be any of the formats described by the PaSampleFormat
872 @param sampleRate Same as Pa_OpenStream parameter of the same name.
873 @param framesPerBuffer Same as Pa_OpenStream parameter of the same name.
874 @param streamCallback Same as Pa_OpenStream parameter of the same name.
875 @param userData Same as Pa_OpenStream parameter of the same name.
877 @return As for Pa_OpenStream
879 @see Pa_OpenStream, PaStreamCallback
881 PaError Pa_OpenDefaultStream( PaStream** stream,
882 int numInputChannels,
883 int numOutputChannels,
884 PaSampleFormat sampleFormat,
886 unsigned long framesPerBuffer,
887 PaStreamCallback *streamCallback,
891 /** Closes an audio stream. If the audio stream is active it
892 discards any pending buffers as if Pa_AbortStream() had been called.
894 PaError Pa_CloseStream( PaStream *stream );
897 /** Functions of type PaStreamFinishedCallback are implemented by PortAudio
898 clients. They can be registered with a stream using the Pa_SetStreamFinishedCallback
899 function. Once registered they are called when the stream becomes inactive
900 (ie once a call to Pa_StopStream() will not block).
901 A stream will become inactive after the stream callback returns non-zero,
902 or when Pa_StopStream or Pa_AbortStream is called. For a stream providing audio
903 output, if the stream callback returns paComplete, or Pa_StopStream is called,
904 the stream finished callback will not be called until all generated sample data
907 @param userData The userData parameter supplied to Pa_OpenStream()
909 @see Pa_SetStreamFinishedCallback
911 typedef void PaStreamFinishedCallback( void *userData );
914 /** Register a stream finished callback function which will be called when the
915 stream becomes inactive. See the description of PaStreamFinishedCallback for
916 further details about when the callback will be called.
918 @param stream a pointer to a PaStream that is in the stopped state - if the
919 stream is not stopped, the stream's finished callback will remain unchanged
920 and an error code will be returned.
922 @param streamFinishedCallback a pointer to a function with the same signature
923 as PaStreamFinishedCallback, that will be called when the stream becomes
924 inactive. Passing NULL for this parameter will un-register a previously
925 registered stream finished callback function.
927 @return on success returns paNoError, otherwise an error code indicating the cause
930 @see PaStreamFinishedCallback
932 PaError Pa_SetStreamFinishedCallback( PaStream *stream, PaStreamFinishedCallback* streamFinishedCallback );
935 /** Commences audio processing.
937 PaError Pa_StartStream( PaStream *stream );
940 /** Terminates audio processing. It waits until all pending
941 audio buffers have been played before it returns.
943 PaError Pa_StopStream( PaStream *stream );
946 /** Terminates audio processing immediately without waiting for pending
949 PaError Pa_AbortStream( PaStream *stream );
952 /** Determine whether the stream is stopped.
953 A stream is considered to be stopped prior to a successful call to
954 Pa_StartStream and after a successful call to Pa_StopStream or Pa_AbortStream.
955 If a stream callback returns a value other than paContinue the stream is NOT
956 considered to be stopped.
958 @return Returns one (1) when the stream is stopped, zero (0) when
959 the stream is running or, a PaErrorCode (which are always negative) if
960 PortAudio is not initialized or an error is encountered.
962 @see Pa_StopStream, Pa_AbortStream, Pa_IsStreamActive
964 PaError Pa_IsStreamStopped( PaStream *stream );
967 /** Determine whether the stream is active.
968 A stream is active after a successful call to Pa_StartStream(), until it
969 becomes inactive either as a result of a call to Pa_StopStream() or
970 Pa_AbortStream(), or as a result of a return value other than paContinue from
971 the stream callback. In the latter case, the stream is considered inactive
972 after the last buffer has finished playing.
974 @return Returns one (1) when the stream is active (ie playing or recording
975 audio), zero (0) when not playing or, a PaErrorCode (which are always negative)
976 if PortAudio is not initialized or an error is encountered.
978 @see Pa_StopStream, Pa_AbortStream, Pa_IsStreamStopped
980 PaError Pa_IsStreamActive( PaStream *stream );
984 /** A structure containing unchanging information about an open stream.
985 @see Pa_GetStreamInfo
988 typedef struct PaStreamInfo
990 /** this is struct version 1 */
993 /** The input latency of the stream in seconds. This value provides the most
994 accurate estimate of input latency available to the implementation. It may
995 differ significantly from the suggestedLatency value passed to Pa_OpenStream().
996 The value of this field will be zero (0.) for output-only streams.
1001 /** The output latency of the stream in seconds. This value provides the most
1002 accurate estimate of output latency available to the implementation. It may
1003 differ significantly from the suggestedLatency value passed to Pa_OpenStream().
1004 The value of this field will be zero (0.) for input-only streams.
1007 PaTime outputLatency;
1009 /** The sample rate of the stream in Hertz (samples per second). In cases
1010 where the hardware sample rate is inaccurate and PortAudio is aware of it,
1011 the value of this field may be different from the sampleRate parameter
1012 passed to Pa_OpenStream(). If information about the actual hardware sample
1013 rate is not available, this field will have the same value as the sampleRate
1014 parameter passed to Pa_OpenStream().
1021 /** Retrieve a pointer to a PaStreamInfo structure containing information
1022 about the specified stream.
1023 @return A pointer to an immutable PaStreamInfo structure. If the stream
1024 parameter invalid, or an error is encountered, the function returns NULL.
1026 @param stream A pointer to an open stream previously created with Pa_OpenStream.
1028 @note PortAudio manages the memory referenced by the returned pointer,
1029 the client must not manipulate or free the memory. The pointer is only
1030 guaranteed to be valid until the specified stream is closed.
1034 const PaStreamInfo* Pa_GetStreamInfo( PaStream *stream );
1037 /** Returns the current time in seconds for a stream according to the same clock used
1038 to generate callback PaStreamCallbackTimeInfo timestamps. The time values are
1039 monotonically increasing and have unspecified origin.
1041 Pa_GetStreamTime returns valid time values for the entire life of the stream,
1042 from when the stream is opened until it is closed. Starting and stopping the stream
1043 does not affect the passage of time returned by Pa_GetStreamTime.
1045 This time may be used for synchronizing other events to the audio stream, for
1046 example synchronizing audio to MIDI.
1048 @return The stream's current time in seconds, or 0 if an error occurred.
1050 @see PaTime, PaStreamCallback, PaStreamCallbackTimeInfo
1052 PaTime Pa_GetStreamTime( PaStream *stream );
1055 /** Retrieve CPU usage information for the specified stream.
1056 The "CPU Load" is a fraction of total CPU time consumed by a callback stream's
1057 audio processing routines including, but not limited to the client supplied
1058 stream callback. This function does not work with blocking read/write streams.
1060 This function may be called from the stream callback function or the
1064 A floating point value, typically between 0.0 and 1.0, where 1.0 indicates
1065 that the stream callback is consuming the maximum number of CPU cycles possible
1066 to maintain real-time operation. A value of 0.5 would imply that PortAudio and
1067 the stream callback was consuming roughly 50% of the available CPU time. The
1068 return value may exceed 1.0. A value of 0.0 will always be returned for a
1069 blocking read/write stream, or if an error occurs.
1071 double Pa_GetStreamCpuLoad( PaStream* stream );
1074 /** Read samples from an input stream. The function doesn't return until
1075 the entire buffer has been filled - this may involve waiting for the operating
1076 system to supply the data.
1078 @param stream A pointer to an open stream previously created with Pa_OpenStream.
1080 @param buffer A pointer to a buffer of sample frames. The buffer contains
1081 samples in the format specified by the inputParameters->sampleFormat field
1082 used to open the stream, and the number of channels specified by
1083 inputParameters->numChannels. If non-interleaved samples were requested using
1084 the paNonInterleaved sample format flag, buffer is a pointer to the first element
1085 of an array of buffer pointers, one non-interleaved buffer for each channel.
1087 @param frames The number of frames to be read into buffer. This parameter
1088 is not constrained to a specific range, however high performance applications
1089 will want to match this parameter to the framesPerBuffer parameter used
1090 when opening the stream.
1092 @return On success PaNoError will be returned, or PaInputOverflowed if input
1093 data was discarded by PortAudio after the previous call and before this call.
1095 PaError Pa_ReadStream( PaStream* stream,
1097 unsigned long frames );
1100 /** Write samples to an output stream. This function doesn't return until the
1101 entire buffer has been consumed - this may involve waiting for the operating
1102 system to consume the data.
1104 @param stream A pointer to an open stream previously created with Pa_OpenStream.
1106 @param buffer A pointer to a buffer of sample frames. The buffer contains
1107 samples in the format specified by the outputParameters->sampleFormat field
1108 used to open the stream, and the number of channels specified by
1109 outputParameters->numChannels. If non-interleaved samples were requested using
1110 the paNonInterleaved sample format flag, buffer is a pointer to the first element
1111 of an array of buffer pointers, one non-interleaved buffer for each channel.
1113 @param frames The number of frames to be written from buffer. This parameter
1114 is not constrained to a specific range, however high performance applications
1115 will want to match this parameter to the framesPerBuffer parameter used
1116 when opening the stream.
1118 @return On success PaNoError will be returned, or paOutputUnderflowed if
1119 additional output data was inserted after the previous call and before this
1122 PaError Pa_WriteStream( PaStream* stream,
1124 unsigned long frames );
1127 /** Retrieve the number of frames that can be read from the stream without
1130 @return Returns a non-negative value representing the maximum number of frames
1131 that can be read from the stream without blocking or busy waiting or, a
1132 PaErrorCode (which are always negative) if PortAudio is not initialized or an
1133 error is encountered.
1135 signed long Pa_GetStreamReadAvailable( PaStream* stream );
1138 /** Retrieve the number of frames that can be written to the stream without
1141 @return Returns a non-negative value representing the maximum number of frames
1142 that can be written to the stream without blocking or busy waiting or, a
1143 PaErrorCode (which are always negative) if PortAudio is not initialized or an
1144 error is encountered.
1146 signed long Pa_GetStreamWriteAvailable( PaStream* stream );
1149 /* Miscellaneous utilities */
1152 /** Retrieve the size of a given sample format in bytes.
1154 @return The size in bytes of a single sample in the specified format,
1155 or paSampleFormatNotSupported if the format is not supported.
1157 PaError Pa_GetSampleSize( PaSampleFormat format );
1160 /** Put the caller to sleep for at least 'msec' milliseconds. This function is
1161 provided only as a convenience for authors of portable code (such as the tests
1162 and examples in the PortAudio distribution.)
1164 The function may sleep longer than requested so don't rely on this for accurate
1167 void Pa_Sleep( long msec );
1173 #endif /* __cplusplus */
1174 #endif /* PORTAUDIO_H */