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portaudio.h

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  1. #ifndef PORTAUDIO_H
  2. #define PORTAUDIO_H
  3. /*
  4.  * $Id: portaudio.h 1594 2011-02-05 14:33:29Z rossb $
  5.  * PortAudio Portable Real-Time Audio Library
  6.  * PortAudio API Header File
  7.  * Latest version available at: http://www.portaudio.com/
  8.  *
  9.  * Copyright (c) 1999-2002 Ross Bencina and Phil Burk
  10.  *
  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:
  18.  *
  19.  * The above copyright notice and this permission notice shall be
  20.  * included in all copies or substantial portions of the Software.
  21.  *
  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.
  29.  */
  30.  
  31. /*
  32.  * The text above constitutes the entire PortAudio license; however,
  33.  * the PortAudio community also makes the following non-binding requests:
  34.  *
  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
  39.  * license above.
  40.  */
  41.  
  42. /** @file
  43.  @ingroup public_header
  44.  @brief The portable PortAudio API.
  45. */
  46.  
  47.  
  48. #ifdef __cplusplus
  49. extern "C"
  50. {
  51. #endif /* __cplusplus */
  52.  
  53.  
  54. /** Retrieve the release number of the currently running PortAudio build,
  55.  eg 1900.
  56. */
  57. int Pa_GetVersion( void );
  58.  
  59.  
  60. /** Retrieve a textual description of the current PortAudio build,
  61.  eg "PortAudio V19-devel 13 October 2002".
  62. */
  63. const char* Pa_GetVersionText( void );
  64.  
  65.  
  66. /** Error codes returned by PortAudio functions.
  67.  Note that with the exception of paNoError, all PaErrorCodes are negative.
  68. */
  69.  
  70. typedef int PaError;
  71. typedef enum PaErrorCode
  72. {
  73.     paNoError = 0,
  74.  
  75.     paNotInitialized = -10000,
  76.     paUnanticipatedHostError,
  77.     paInvalidChannelCount,
  78.     paInvalidSampleRate,
  79.     paInvalidDevice,
  80.     paInvalidFlag,
  81.     paSampleFormatNotSupported,
  82.     paBadIODeviceCombination,
  83.     paInsufficientMemory,
  84.     paBufferTooBig,
  85.     paBufferTooSmall,
  86.     paNullCallback,
  87.     paBadStreamPtr,
  88.     paTimedOut,
  89.     paInternalError,
  90.     paDeviceUnavailable,
  91.     paIncompatibleHostApiSpecificStreamInfo,
  92.     paStreamIsStopped,
  93.     paStreamIsNotStopped,
  94.     paInputOverflowed,
  95.     paOutputUnderflowed,
  96.     paHostApiNotFound,
  97.     paInvalidHostApi,
  98.     paCanNotReadFromACallbackStream,
  99.     paCanNotWriteToACallbackStream,
  100.     paCanNotReadFromAnOutputOnlyStream,
  101.     paCanNotWriteToAnInputOnlyStream,
  102.     paIncompatibleStreamHostApi,
  103.     paBadBufferPtr
  104. } PaErrorCode;
  105.  
  106.  
  107. /** Translate the supplied PortAudio error code into a human readable
  108.  message.
  109. */
  110. const char *Pa_GetErrorText( PaError errorCode );
  111.  
  112.  
  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.
  118.  
  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.
  123.  
  124.  Note that if Pa_Initialize() returns an error code, Pa_Terminate() should
  125.  NOT be called.
  126.  
  127.  @return paNoError if successful, otherwise an error code indicating the cause
  128.  of failure.
  129.  
  130.  @see Pa_Terminate
  131. */
  132. PaError Pa_Initialize( void );
  133.  
  134.  
  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.
  141.  
  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.
  145.  
  146.  @return paNoError if successful, otherwise an error code indicating the cause
  147.  of failure.
  148.  
  149.  @see Pa_Initialize
  150. */
  151. PaError Pa_Terminate( void );
  152.  
  153.  
  154.  
  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.
  158.  
  159.  @see Pa_GetDeviceCount, paNoDevice, paUseHostApiSpecificDeviceSpecification
  160. */
  161. typedef int PaDeviceIndex;
  162.  
  163.  
  164. /** A special PaDeviceIndex value indicating that no device is available,
  165.  or should be used.
  166.  
  167.  @see PaDeviceIndex
  168. */
  169. #define paNoDevice ((PaDeviceIndex)-1)
  170.  
  171.  
  172. /** A special PaDeviceIndex value indicating that the device(s) to be used
  173.  are specified in the host api specific stream info structure.
  174.  
  175.  @see PaDeviceIndex
  176. */
  177. #define paUseHostApiSpecificDeviceSpecification ((PaDeviceIndex)-2)
  178.  
  179.  
  180. /* Host API enumeration mechanism */
  181.  
  182. /** The type used to enumerate to host APIs at runtime. Values of this type
  183.  range from 0 to (Pa_GetHostApiCount()-1).
  184.  
  185.  @see Pa_GetHostApiCount
  186. */
  187. typedef int PaHostApiIndex;
  188.  
  189.  
  190. /** Retrieve the number of available host APIs. Even if a host API is
  191.  available it may have no devices available.
  192.  
  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.
  196.  
  197.  @see PaHostApiIndex
  198. */
  199. PaHostApiIndex Pa_GetHostApiCount( void );
  200.  
  201.  
  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.
  205.  
  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.
  209. */
  210. PaHostApiIndex Pa_GetDefaultHostApi( void );
  211.  
  212.  
  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.
  217.  
  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.
  221.  
  222.  @see PaHostApiInfo
  223. */
  224. typedef enum PaHostApiTypeId
  225. {
  226.     paInDevelopment=0, /* use while developing support for a new host API */
  227.     paDirectSound=1,
  228.     paMME=2,
  229.     paASIO=3,
  230.     paSoundManager=4,
  231.     paCoreAudio=5,
  232.     paOSS=7,
  233.     paALSA=8,
  234.     paAL=9,
  235.     paBeOS=10,
  236.     paWDMKS=11,
  237.     paJACK=12,
  238.     paWASAPI=13,
  239.     paAudioScienceHPI=14
  240. } PaHostApiTypeId;
  241.  
  242.  
  243. /** A structure containing information about a particular host API. */
  244.  
  245. typedef struct PaHostApiInfo
  246. {
  247.     /** this is struct version 1 */
  248.     int structVersion;
  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. */
  252.     const char *name;
  253.  
  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
  258.     */
  259.     int deviceCount;
  260.  
  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.
  264.     */
  265.     PaDeviceIndex defaultInputDevice;
  266.  
  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.
  270.     */
  271.     PaDeviceIndex defaultOutputDevice;
  272.    
  273. } PaHostApiInfo;
  274.  
  275.  
  276. /** Retrieve a pointer to a structure containing information about a specific
  277.  host Api.
  278.  
  279.  @param hostApi A valid host API index ranging from 0 to (Pa_GetHostApiCount()-1)
  280.  
  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.
  284.  
  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().
  288. */
  289. const PaHostApiInfo * Pa_GetHostApiInfo( PaHostApiIndex hostApi );
  290.  
  291.  
  292. /** Convert a static host API unique identifier, into a runtime
  293.  host API index.
  294.  
  295.  @param type A unique host API identifier belonging to the PaHostApiTypeId
  296.  enumeration.
  297.  
  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.
  301.  
  302.  The paHostApiNotFound error code indicates that the host API specified by the
  303.  type parameter is not available.
  304.  
  305.  @see PaHostApiTypeId
  306. */
  307. PaHostApiIndex Pa_HostApiTypeIdToHostApiIndex( PaHostApiTypeId type );
  308.  
  309.  
  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.
  313.  
  314.  @param hostApi A valid host API index ranging from 0 to (Pa_GetHostApiCount()-1)
  315.  
  316.  @param hostApiDeviceIndex A valid per-host device index in the range
  317.  0 to (Pa_GetHostApiInfo(hostApi)->deviceCount-1)
  318.  
  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.
  322.  
  323.  A paInvalidHostApi error code indicates that the host API index specified by
  324.  the hostApi parameter is out of range.
  325.  
  326.  A paInvalidDevice error code indicates that the hostApiDeviceIndex parameter
  327.  is out of range.
  328.  
  329.  @see PaHostApiInfo
  330. */
  331. PaDeviceIndex Pa_HostApiDeviceIndexToDeviceIndex( PaHostApiIndex hostApi,
  332.         int hostApiDeviceIndex );
  333.  
  334.  
  335.  
  336. /** Structure used to return information about a host error condition.
  337. */
  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 */
  342. }PaHostErrorInfo;
  343.  
  344.  
  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.)
  349.  
  350.  This function is provided as a last resort, primarily to enhance debugging
  351.  by providing clients with access to all available error information.
  352.  
  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
  356.  error code.
  357. */
  358. const PaHostErrorInfo* Pa_GetLastHostErrorInfo( void );
  359.  
  360.  
  361.  
  362. /* Device enumeration and capabilities */
  363.  
  364. /** Retrieve the number of available devices. The number of available devices
  365.  may be zero.
  366.  
  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.
  370. */
  371. PaDeviceIndex Pa_GetDeviceCount( void );
  372.  
  373.  
  374. /** Retrieve the index of the default input device. The result can be
  375.  used in the inputDevice parameter to Pa_OpenStream().
  376.  
  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.
  379. */
  380. PaDeviceIndex Pa_GetDefaultInputDevice( void );
  381.  
  382.  
  383. /** Retrieve the index of the default output device. The result can be
  384.  used in the outputDevice parameter to Pa_OpenStream().
  385.  
  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.
  388.  
  389.  @note
  390.  On the PC, the user can specify a default device by
  391.  setting an environment variable. For example, to use device #1.
  392. <pre>
  393.  set PA_RECOMMENDED_OUTPUT_DEVICE=1
  394. </pre>
  395.  The user should first determine the available device ids by using
  396.  the supplied application "pa_devs".
  397. */
  398. PaDeviceIndex Pa_GetDefaultOutputDevice( void );
  399.  
  400.  
  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().
  404.  
  405.  PaTime values have unspecified origin.
  406.      
  407.  @see PaStreamCallback, PaStreamCallbackTimeInfo, Pa_GetStreamTime
  408. */
  409. typedef double PaTime;
  410.  
  411.  
  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.
  415.  
  416.  The standard formats paFloat32, paInt16, paInt32, paInt24, paInt8
  417.  and aUInt8 are usually implemented by all implementations.
  418.  
  419.  The floating point representation (paFloat32) uses +1.0 and -1.0 as the
  420.  maximum and minimum respectively.
  421.  
  422.  paUInt8 is an unsigned 8 bit format where 128 is considered "ground"
  423.  
  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.
  428.  
  429.  @see Pa_OpenStream, Pa_OpenDefaultStream, PaDeviceInfo
  430.  @see paFloat32, paInt16, paInt32, paInt24, paInt8
  431.  @see paUInt8, paCustomFormat, paNonInterleaved
  432. */
  433. typedef unsigned long PaSampleFormat;
  434.  
  435.  
  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 */
  443.  
  444. #define paNonInterleaved ((PaSampleFormat) 0x80000000) /**< @see PaSampleFormat */
  445.  
  446. /** A structure providing information and capabilities of PortAudio devices.
  447.  Devices may support input, output or both input and output.
  448. */
  449. typedef struct PaDeviceInfo
  450. {
  451.     int structVersion;  /* this is struct version 2 */
  452.     const char *name;
  453.     PaHostApiIndex hostApi; /* note this is a host API index, not a type id*/
  454.    
  455.     int maxInputChannels;
  456.     int maxOutputChannels;
  457.  
  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;
  464.  
  465.     double defaultSampleRate;
  466. } PaDeviceInfo;
  467.  
  468.  
  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.
  473.  
  474.  @param device A valid device index in the range 0 to (Pa_GetDeviceCount()-1)
  475.  
  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().
  479.  
  480.  @see PaDeviceInfo, PaDeviceIndex
  481. */
  482. const PaDeviceInfo* Pa_GetDeviceInfo( PaDeviceIndex device );
  483.  
  484.  
  485. /** Parameters for one direction (input or output) of a stream.
  486. */
  487. typedef struct PaStreamParameters
  488. {
  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.
  494.     */
  495.     PaDeviceIndex device;
  496.    
  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.
  501.     */
  502.     int channelCount;
  503.  
  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.
  507.     */
  508.     PaSampleFormat sampleFormat;
  509.  
  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
  520.     */
  521.     PaTime suggestedLatency;
  522.  
  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.
  527.     */
  528.     void *hostApiSpecificStreamInfo;
  529.  
  530. } PaStreamParameters;
  531.  
  532.  
  533. /** Return code for Pa_IsFormatSupported indicating success. */
  534. #define paFormatIsSupported (0)
  535.  
  536. /** Determine whether it would be possible to open a stream with the specified
  537.  parameters.
  538.  
  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
  542.  output-only streams.
  543.  
  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
  547.  input-only streams.
  548.  
  549.  @param sampleRate The required sampleRate. For full-duplex streams it is the
  550.  sample rate for both input and output
  551.  
  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.
  555.  
  556.  @see paFormatIsSupported, PaStreamParameters
  557. */
  558. PaError Pa_IsFormatSupported( const PaStreamParameters *inputParameters,
  559.                               const PaStreamParameters *outputParameters,
  560.                               double sampleRate );
  561.  
  562.  
  563.  
  564. /* Streaming types and functions */
  565.  
  566.  
  567. /**
  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.
  575.  
  576.  Pointers to PaStream objects are passed between PortAudio functions that
  577.  operate on streams.
  578.  
  579.  @see Pa_OpenStream, Pa_OpenDefaultStream, Pa_OpenDefaultStream, Pa_CloseStream,
  580.  Pa_StartStream, Pa_StopStream, Pa_AbortStream, Pa_IsStreamActive,
  581.  Pa_GetStreamTime, Pa_GetStreamCpuLoad
  582.  
  583. */
  584. typedef void PaStream;
  585.  
  586.  
  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.
  590. */
  591. #define paFramesPerBufferUnspecified  (0)
  592.  
  593.  
  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
  596.  ORed together.
  597.  
  598.  @see Pa_OpenStream, Pa_OpenDefaultStream
  599.  @see paNoFlag, paClipOff, paDitherOff, paNeverDropInput,
  600.   paPrimeOutputBuffersUsingStreamCallback, paPlatformSpecificFlags
  601. */
  602. typedef unsigned long PaStreamFlags;
  603.  
  604. /** @see PaStreamFlags */
  605. #define   paNoFlag          ((PaStreamFlags) 0)
  606.  
  607. /** Disable default clipping of out of range samples.
  608.  @see PaStreamFlags
  609. */
  610. #define   paClipOff         ((PaStreamFlags) 0x00000001)
  611.  
  612. /** Disable default dithering.
  613.  @see PaStreamFlags
  614. */
  615. #define   paDitherOff       ((PaStreamFlags) 0x00000002)
  616.  
  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.
  623.  
  624.  @see PaStreamFlags, paFramesPerBufferUnspecified
  625. */
  626. #define   paNeverDropInput  ((PaStreamFlags) 0x00000004)
  627.  
  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.
  631.  
  632.  @see PaStreamFlags
  633. */
  634. #define   paPrimeOutputBuffersUsingStreamCallback ((PaStreamFlags) 0x00000008)
  635.  
  636. /** A mask specifying the platform specific bits.
  637.  @see PaStreamFlags
  638. */
  639. #define   paPlatformSpecificFlags ((PaStreamFlags)0xFFFF0000)
  640.  
  641. /**
  642.  Timing information for the buffers passed to the stream callback.
  643. */
  644. typedef struct PaStreamCallbackTimeInfo{
  645.     PaTime inputBufferAdcTime;
  646.     PaTime currentTime;
  647.     PaTime outputBufferDacTime;
  648. } PaStreamCallbackTimeInfo;
  649.  
  650.  
  651. /**
  652.  Flag bit constants for the statusFlags to PaStreamCallback.
  653.  
  654.  @see paInputUnderflow, paInputOverflow, paOutputUnderflow, paOutputOverflow,
  655.  paPrimingOutput
  656. */
  657. typedef unsigned long PaStreamCallbackFlags;
  658.  
  659. /** In a stream opened with paFramesPerBufferUnspecified, indicates that
  660.  input data is all silence (zeros) because no real data is available. In a
  661.  stream opened without paFramesPerBufferUnspecified, it indicates that one or
  662.  more zero samples have been inserted into the input buffer to compensate
  663.  for an input underflow.
  664.  @see PaStreamCallbackFlags
  665. */
  666. #define paInputUnderflow   ((PaStreamCallbackFlags) 0x00000001)
  667.  
  668. /** In a stream opened with paFramesPerBufferUnspecified, indicates that data
  669.  prior to the first sample of the input buffer was discarded due to an
  670.  overflow, possibly because the stream callback is using too much CPU time.
  671.  Otherwise indicates that data prior to one or more samples in the
  672.  input buffer was discarded.
  673.  @see PaStreamCallbackFlags
  674. */
  675. #define paInputOverflow    ((PaStreamCallbackFlags) 0x00000002)
  676.  
  677. /** Indicates that output data (or a gap) was inserted, possibly because the
  678.  stream callback is using too much CPU time.
  679.  @see PaStreamCallbackFlags
  680. */
  681. #define paOutputUnderflow  ((PaStreamCallbackFlags) 0x00000004)
  682.  
  683. /** Indicates that output data will be discarded because no room is available.
  684.  @see PaStreamCallbackFlags
  685. */
  686. #define paOutputOverflow   ((PaStreamCallbackFlags) 0x00000008)
  687.  
  688. /** Some of all of the output data will be used to prime the stream, input
  689.  data may be zero.
  690.  @see PaStreamCallbackFlags
  691. */
  692. #define paPrimingOutput    ((PaStreamCallbackFlags) 0x00000010)
  693.  
  694. /**
  695.  Allowable return values for the PaStreamCallback.
  696.  @see PaStreamCallback
  697. */
  698. typedef enum PaStreamCallbackResult
  699. {
  700.     paContinue=0,
  701.     paComplete=1,
  702.     paAbort=2
  703. } PaStreamCallbackResult;
  704.  
  705.  
  706. /**
  707.  Functions of type PaStreamCallback are implemented by PortAudio clients.
  708.  They consume, process or generate audio in response to requests from an
  709.  active PortAudio stream.
  710.      
  711.  @param input and @param output are either arrays of interleaved samples or;
  712.  if non-interleaved samples were requested using the paNonInterleaved sample
  713.  format flag, an array of buffer pointers, one non-interleaved buffer for
  714.  each channel.
  715.  
  716.  The format, packing and number of channels used by the buffers are
  717.  determined by parameters to Pa_OpenStream().
  718.      
  719.  @param frameCount The number of sample frames to be processed by
  720.  the stream callback.
  721.  
  722.  @param timeInfo The time in seconds when the first sample of the input
  723.  buffer was received at the audio input, the time in seconds when the first
  724.  sample of the output buffer will begin being played at the audio output, and
  725.  the time in seconds when the stream callback was called.
  726.  See also Pa_GetStreamTime()
  727.  
  728.  @param statusFlags Flags indicating whether input and/or output buffers
  729.  have been inserted or will be dropped to overcome underflow or overflow
  730.  conditions.
  731.  
  732.  @param userData The value of a user supplied pointer passed to
  733.  Pa_OpenStream() intended for storing synthesis data etc.
  734.  
  735.  @return
  736.  The stream callback should return one of the values in the
  737.  PaStreamCallbackResult enumeration. To ensure that the callback continues
  738.  to be called, it should return paContinue (0). Either paComplete or paAbort
  739.  can be returned to finish stream processing, after either of these values is
  740.  returned the callback will not be called again. If paAbort is returned the
  741.  stream will finish as soon as possible. If paComplete is returned, the stream
  742.  will continue until all buffers generated by the callback have been played.
  743.  This may be useful in applications such as soundfile players where a specific
  744.  duration of output is required. However, it is not necessary to utilize this
  745.  mechanism as Pa_StopStream(), Pa_AbortStream() or Pa_CloseStream() can also
  746.  be used to stop the stream. The callback must always fill the entire output
  747.  buffer irrespective of its return value.
  748.  
  749.  @see Pa_OpenStream, Pa_OpenDefaultStream
  750.  
  751.  @note With the exception of Pa_GetStreamCpuLoad() it is not permissible to call
  752.  PortAudio API functions from within the stream callback.
  753. */
  754. typedef int PaStreamCallback(
  755.     const void *input, void *output,
  756.     unsigned long frameCount,
  757.     const PaStreamCallbackTimeInfo* timeInfo,
  758.     PaStreamCallbackFlags statusFlags,
  759.     void *userData );
  760.  
  761.  
  762. /** Opens a stream for either input, output or both.
  763.      
  764.  @param stream The address of a PaStream pointer which will receive
  765.  a pointer to the newly opened stream.
  766.      
  767.  @param inputParameters A structure that describes the input parameters used by
  768.  the opened stream. See PaStreamParameters for a description of these parameters.
  769.  inputParameters must be NULL for output-only streams.
  770.  
  771.  @param outputParameters A structure that describes the output parameters used by
  772.  the opened stream. See PaStreamParameters for a description of these parameters.
  773.  outputParameters must be NULL for input-only streams.
  774.  
  775.  @param sampleRate The desired sampleRate. For full-duplex streams it is the
  776.  sample rate for both input and output
  777.      
  778.  @param framesPerBuffer The number of frames passed to the stream callback
  779.  function, or the preferred block granularity for a blocking read/write stream.
  780.  The special value paFramesPerBufferUnspecified (0) may be used to request that
  781.  the stream callback will receive an optimal (and possibly varying) number of
  782.  frames based on host requirements and the requested latency settings.
  783.  Note: With some host APIs, the use of non-zero framesPerBuffer for a callback
  784.  stream may introduce an additional layer of buffering which could introduce
  785.  additional latency. PortAudio guarantees that the additional latency
  786.  will be kept to the theoretical minimum however, it is strongly recommended
  787.  that a non-zero framesPerBuffer value only be used when your algorithm
  788.  requires a fixed number of frames per stream callback.
  789.  
  790.  @param streamFlags Flags which modify the behavior of the streaming process.
  791.  This parameter may contain a combination of flags ORed together. Some flags may
  792.  only be relevant to certain buffer formats.
  793.      
  794.  @param streamCallback A pointer to a client supplied function that is responsible
  795.  for processing and filling input and output buffers. If this parameter is NULL
  796.  the stream will be opened in 'blocking read/write' mode. In blocking mode,
  797.  the client can receive sample data using Pa_ReadStream and write sample data
  798.  using Pa_WriteStream, the number of samples that may be read or written
  799.  without blocking is returned by Pa_GetStreamReadAvailable and
  800.  Pa_GetStreamWriteAvailable respectively.
  801.  
  802.  @param userData A client supplied pointer which is passed to the stream callback
  803.  function. It could for example, contain a pointer to instance data necessary
  804.  for processing the audio buffers. This parameter is ignored if streamCallback
  805.  is NULL.
  806.      
  807.  @return
  808.  Upon success Pa_OpenStream() returns paNoError and places a pointer to a
  809.  valid PaStream in the stream argument. The stream is inactive (stopped).
  810.  If a call to Pa_OpenStream() fails, a non-zero error code is returned (see
  811.  PaError for possible error codes) and the value of stream is invalid.
  812.  
  813.  @see PaStreamParameters, PaStreamCallback, Pa_ReadStream, Pa_WriteStream,
  814.  Pa_GetStreamReadAvailable, Pa_GetStreamWriteAvailable
  815. */
  816. PaError Pa_OpenStream( PaStream** stream,
  817.                        const PaStreamParameters *inputParameters,
  818.                        const PaStreamParameters *outputParameters,
  819.                        double sampleRate,
  820.                        unsigned long framesPerBuffer,
  821.                        PaStreamFlags streamFlags,
  822.                        PaStreamCallback *streamCallback,
  823.                        void *userData );
  824.  
  825.  
  826. /** A simplified version of Pa_OpenStream() that opens the default input
  827.  and/or output devices.
  828.  
  829.  @param stream The address of a PaStream pointer which will receive
  830.  a pointer to the newly opened stream.
  831.  
  832.  @param numInputChannels  The number of channels of sound that will be supplied
  833.  to the stream callback or returned by Pa_ReadStream. It can range from 1 to
  834.  the value of maxInputChannels in the PaDeviceInfo record for the default input
  835.  device. If 0 the stream is opened as an output-only stream.
  836.  
  837.  @param numOutputChannels The number of channels of sound to be delivered to the
  838.  stream callback or passed to Pa_WriteStream. It can range from 1 to the value
  839.  of maxOutputChannels in the PaDeviceInfo record for the default output device.
  840.  If 0 the stream is opened as an output-only stream.
  841.  
  842.  @param sampleFormat The sample format of both the input and output buffers
  843.  provided to the callback or passed to and from Pa_ReadStream and Pa_WriteStream.
  844.  sampleFormat may be any of the formats described by the PaSampleFormat
  845.  enumeration.
  846.  
  847.  @param sampleRate Same as Pa_OpenStream parameter of the same name.
  848.  @param framesPerBuffer Same as Pa_OpenStream parameter of the same name.
  849.  @param streamCallback Same as Pa_OpenStream parameter of the same name.
  850.  @param userData Same as Pa_OpenStream parameter of the same name.
  851.  
  852.  @return As for Pa_OpenStream
  853.  
  854.  @see Pa_OpenStream, PaStreamCallback
  855. */
  856. PaError Pa_OpenDefaultStream( PaStream** stream,
  857.                               int numInputChannels,
  858.                               int numOutputChannels,
  859.                               PaSampleFormat sampleFormat,
  860.                               double sampleRate,
  861.                               unsigned long framesPerBuffer,
  862.                               PaStreamCallback *streamCallback,
  863.                               void *userData );
  864.  
  865.  
  866. /** Closes an audio stream. If the audio stream is active it
  867.  discards any pending buffers as if Pa_AbortStream() had been called.
  868. */
  869. PaError Pa_CloseStream( PaStream *stream );
  870.  
  871.  
  872. /** Functions of type PaStreamFinishedCallback are implemented by PortAudio
  873.  clients. They can be registered with a stream using the Pa_SetStreamFinishedCallback
  874.  function. Once registered they are called when the stream becomes inactive
  875.  (ie once a call to Pa_StopStream() will not block).
  876.  A stream will become inactive after the stream callback returns non-zero,
  877.  or when Pa_StopStream or Pa_AbortStream is called. For a stream providing audio
  878.  output, if the stream callback returns paComplete, or Pa_StopStream is called,
  879.  the stream finished callback will not be called until all generated sample data
  880.  has been played.
  881.  
  882.  @param userData The userData parameter supplied to Pa_OpenStream()
  883.  
  884.  @see Pa_SetStreamFinishedCallback
  885. */
  886. typedef void PaStreamFinishedCallback( void *userData );
  887.  
  888.  
  889. /** Register a stream finished callback function which will be called when the
  890.  stream becomes inactive. See the description of PaStreamFinishedCallback for
  891.  further details about when the callback will be called.
  892.  
  893.  @param stream a pointer to a PaStream that is in the stopped state - if the
  894.  stream is not stopped, the stream's finished callback will remain unchanged
  895.  and an error code will be returned.
  896.  
  897.  @param streamFinishedCallback a pointer to a function with the same signature
  898.  as PaStreamFinishedCallback, that will be called when the stream becomes
  899.  inactive. Passing NULL for this parameter will un-register a previously
  900.  registered stream finished callback function.
  901.  
  902.  @return on success returns paNoError, otherwise an error code indicating the cause
  903.  of the error.
  904.  
  905.  @see PaStreamFinishedCallback
  906. */
  907. PaError Pa_SetStreamFinishedCallback( PaStream *stream, PaStreamFinishedCallback* streamFinishedCallback );
  908.  
  909.  
  910. /** Commences audio processing.
  911. */
  912. PaError Pa_StartStream( PaStream *stream );
  913.  
  914.  
  915. /** Terminates audio processing. It waits until all pending
  916.  audio buffers have been played before it returns.
  917. */
  918. PaError Pa_StopStream( PaStream *stream );
  919.  
  920.  
  921. /** Terminates audio processing immediately without waiting for pending
  922.  buffers to complete.
  923. */
  924. PaError Pa_AbortStream( PaStream *stream );
  925.  
  926.  
  927. /** Determine whether the stream is stopped.
  928.  A stream is considered to be stopped prior to a successful call to
  929.  Pa_StartStream and after a successful call to Pa_StopStream or Pa_AbortStream.
  930.  If a stream callback returns a value other than paContinue the stream is NOT
  931.  considered to be stopped.
  932.  
  933.  @return Returns one (1) when the stream is stopped, zero (0) when
  934.  the stream is running or, a PaErrorCode (which are always negative) if
  935.  PortAudio is not initialized or an error is encountered.
  936.  
  937.  @see Pa_StopStream, Pa_AbortStream, Pa_IsStreamActive
  938. */
  939. PaError Pa_IsStreamStopped( PaStream *stream );
  940.  
  941.  
  942. /** Determine whether the stream is active.
  943.  A stream is active after a successful call to Pa_StartStream(), until it
  944.  becomes inactive either as a result of a call to Pa_StopStream() or
  945.  Pa_AbortStream(), or as a result of a return value other than paContinue from
  946.  the stream callback. In the latter case, the stream is considered inactive
  947.  after the last buffer has finished playing.
  948.  
  949.  @return Returns one (1) when the stream is active (ie playing or recording
  950.  audio), zero (0) when not playing or, a PaErrorCode (which are always negative)
  951.  if PortAudio is not initialized or an error is encountered.
  952.  
  953.  @see Pa_StopStream, Pa_AbortStream, Pa_IsStreamStopped
  954. */
  955. PaError Pa_IsStreamActive( PaStream *stream );
  956.  
  957.  
  958.  
  959. /** A structure containing unchanging information about an open stream.
  960.  @see Pa_GetStreamInfo
  961. */
  962.  
  963. typedef struct PaStreamInfo
  964. {
  965.     /** this is struct version 1 */
  966.     int structVersion;
  967.  
  968.     /** The input latency of the stream in seconds. This value provides the most
  969.      accurate estimate of input latency available to the implementation. It may
  970.      differ significantly from the suggestedLatency value passed to Pa_OpenStream().
  971.      The value of this field will be zero (0.) for output-only streams.
  972.      @see PaTime
  973.     */
  974.     PaTime inputLatency;
  975.  
  976.     /** The output latency of the stream in seconds. This value provides the most
  977.      accurate estimate of output latency available to the implementation. It may
  978.      differ significantly from the suggestedLatency value passed to Pa_OpenStream().
  979.      The value of this field will be zero (0.) for input-only streams.
  980.      @see PaTime
  981.     */
  982.     PaTime outputLatency;
  983.  
  984.     /** The sample rate of the stream in Hertz (samples per second). In cases
  985.      where the hardware sample rate is inaccurate and PortAudio is aware of it,
  986.      the value of this field may be different from the sampleRate parameter
  987.      passed to Pa_OpenStream(). If information about the actual hardware sample
  988.      rate is not available, this field will have the same value as the sampleRate
  989.      parameter passed to Pa_OpenStream().
  990.     */
  991.     double sampleRate;
  992.    
  993. } PaStreamInfo;
  994.  
  995.  
  996. /** Retrieve a pointer to a PaStreamInfo structure containing information
  997.  about the specified stream.
  998.  @return A pointer to an immutable PaStreamInfo structure. If the stream
  999.  parameter invalid, or an error is encountered, the function returns NULL.
  1000.  
  1001.  @param stream A pointer to an open stream previously created with Pa_OpenStream.
  1002.  
  1003.  @note PortAudio manages the memory referenced by the returned pointer,
  1004.  the client must not manipulate or free the memory. The pointer is only
  1005.  guaranteed to be valid until the specified stream is closed.
  1006.  
  1007.  @see PaStreamInfo
  1008. */
  1009. const PaStreamInfo* Pa_GetStreamInfo( PaStream *stream );
  1010.  
  1011.  
  1012. /** Returns the current time in seconds for a stream according to the same clock used
  1013.  to generate callback PaStreamCallbackTimeInfo timestamps. The time values are
  1014.  monotonically increasing and have unspecified origin.
  1015.  
  1016.  Pa_GetStreamTime returns valid time values for the entire life of the stream,
  1017.  from when the stream is opened until it is closed. Starting and stopping the stream
  1018.  does not affect the passage of time returned by Pa_GetStreamTime.
  1019.  
  1020.  This time may be used for synchronizing other events to the audio stream, for
  1021.  example synchronizing audio to MIDI.
  1022.                                        
  1023.  @return The stream's current time in seconds, or 0 if an error occurred.
  1024.  
  1025.  @see PaTime, PaStreamCallback, PaStreamCallbackTimeInfo
  1026. */
  1027. PaTime Pa_GetStreamTime( PaStream *stream );
  1028.  
  1029.  
  1030. /** Retrieve CPU usage information for the specified stream.
  1031.  The "CPU Load" is a fraction of total CPU time consumed by a callback stream's
  1032.  audio processing routines including, but not limited to the client supplied
  1033.  stream callback. This function does not work with blocking read/write streams.
  1034.  
  1035.  This function may be called from the stream callback function or the
  1036.  application.
  1037.      
  1038.  @return
  1039.  A floating point value, typically between 0.0 and 1.0, where 1.0 indicates
  1040.  that the stream callback is consuming the maximum number of CPU cycles possible
  1041.  to maintain real-time operation. A value of 0.5 would imply that PortAudio and
  1042.  the stream callback was consuming roughly 50% of the available CPU time. The
  1043.  return value may exceed 1.0. A value of 0.0 will always be returned for a
  1044.  blocking read/write stream, or if an error occurs.
  1045. */
  1046. double Pa_GetStreamCpuLoad( PaStream* stream );
  1047.  
  1048.  
  1049. /** Read samples from an input stream. The function doesn't return until
  1050.  the entire buffer has been filled - this may involve waiting for the operating
  1051.  system to supply the data.
  1052.  
  1053.  @param stream A pointer to an open stream previously created with Pa_OpenStream.
  1054.  
  1055.  @param buffer A pointer to a buffer of sample frames. The buffer contains
  1056.  samples in the format specified by the inputParameters->sampleFormat field
  1057.  used to open the stream, and the number of channels specified by
  1058.  inputParameters->numChannels. If non-interleaved samples were requested using
  1059.  the paNonInterleaved sample format flag, buffer is a pointer to the first element
  1060.  of an array of buffer pointers, one non-interleaved buffer for each channel.
  1061.  
  1062.  @param frames The number of frames to be read into buffer. This parameter
  1063.  is not constrained to a specific range, however high performance applications
  1064.  will want to match this parameter to the framesPerBuffer parameter used
  1065.  when opening the stream.
  1066.  
  1067.  @return On success PaNoError will be returned, or PaInputOverflowed if input
  1068.  data was discarded by PortAudio after the previous call and before this call.
  1069. */
  1070. PaError Pa_ReadStream( PaStream* stream,
  1071.                        void *buffer,
  1072.                        unsigned long frames );
  1073.  
  1074.  
  1075. /** Write samples to an output stream. This function doesn't return until the
  1076.  entire buffer has been consumed - this may involve waiting for the operating
  1077.  system to consume the data.
  1078.  
  1079.  @param stream A pointer to an open stream previously created with Pa_OpenStream.
  1080.  
  1081.  @param buffer A pointer to a buffer of sample frames. The buffer contains
  1082.  samples in the format specified by the outputParameters->sampleFormat field
  1083.  used to open the stream, and the number of channels specified by
  1084.  outputParameters->numChannels. If non-interleaved samples were requested using
  1085.  the paNonInterleaved sample format flag, buffer is a pointer to the first element
  1086.  of an array of buffer pointers, one non-interleaved buffer for each channel.
  1087.  
  1088.  @param frames The number of frames to be written from buffer. This parameter
  1089.  is not constrained to a specific range, however high performance applications
  1090.  will want to match this parameter to the framesPerBuffer parameter used
  1091.  when opening the stream.
  1092.  
  1093.  @return On success PaNoError will be returned, or paOutputUnderflowed if
  1094.  additional output data was inserted after the previous call and before this
  1095.  call.
  1096. */
  1097. PaError Pa_WriteStream( PaStream* stream,
  1098.                         const void *buffer,
  1099.                         unsigned long frames );
  1100.  
  1101.  
  1102. /** Retrieve the number of frames that can be read from the stream without
  1103.  waiting.
  1104.  
  1105.  @return Returns a non-negative value representing the maximum number of frames
  1106.  that can be read from the stream without blocking or busy waiting or, a
  1107.  PaErrorCode (which are always negative) if PortAudio is not initialized or an
  1108.  error is encountered.
  1109. */
  1110. signed long Pa_GetStreamReadAvailable( PaStream* stream );
  1111.  
  1112.  
  1113. /** Retrieve the number of frames that can be written to the stream without
  1114.  waiting.
  1115.  
  1116.  @return Returns a non-negative value representing the maximum number of frames
  1117.  that can be written to the stream without blocking or busy waiting or, a
  1118.  PaErrorCode (which are always negative) if PortAudio is not initialized or an
  1119.  error is encountered.
  1120. */
  1121. signed long Pa_GetStreamWriteAvailable( PaStream* stream );
  1122.  
  1123.  
  1124. /* Miscellaneous utilities */
  1125.  
  1126.  
  1127. /** Retrieve the size of a given sample format in bytes.
  1128.  
  1129.  @return The size in bytes of a single sample in the specified format,
  1130.  or paSampleFormatNotSupported if the format is not supported.
  1131. */
  1132. PaError Pa_GetSampleSize( PaSampleFormat format );
  1133.  
  1134.  
  1135. /** Put the caller to sleep for at least 'msec' milliseconds. This function is
  1136.  provided only as a convenience for authors of portable code (such as the tests
  1137.  and examples in the PortAudio distribution.)
  1138.  
  1139.  The function may sleep longer than requested so don't rely on this for accurate
  1140.  musical timing.
  1141. */
  1142. void Pa_Sleep( long msec );
  1143.  
  1144.  
  1145.  
  1146. #ifdef __cplusplus
  1147. }
  1148. #endif /* __cplusplus */
  1149. #endif /* PORTAUDIO_H */