comparison win64-msvc/include/portaudio.h @ 45:d530e058a1c1

64-bit MSVC builds

+#ifndef PORTAUDIO_H
+#define PORTAUDIO_H
+/*
+ * $Id: portaudio.h 1859 2012-09-01 00:10:13Z philburk $
+ * PortAudio Portable Real-Time Audio Library
+ * PortAudio API Header File
+ * Latest version available at: http://www.portaudio.com/
+ *
+ * Copyright (c) 1999-2002 Ross Bencina and Phil Burk
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining
+ * a copy of this software and associated documentation files
+ * (the "Software"), to deal in the Software without restriction,
+ * including without limitation the rights to use, copy, modify, merge,
+ * publish, distribute, sublicense, and/or sell copies of the Software,
+ * and to permit persons to whom the Software is furnished to do so,
+ * subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be
+ * included in all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+ * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+ * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
+ * IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR
+ * ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF
+ * CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
+ * WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+ */
+
+/*
+ * The text above constitutes the entire PortAudio license; however, 
+ * the PortAudio community also makes the following non-binding requests:
+ *
+ * Any person wishing to distribute modifications to the Software is
+ * requested to send the modifications to the original developer so that
+ * they can be incorporated into the canonical version. It is also 
+ * requested that these non-binding requests be included along with the 
+ * license above.
+ */
+
+/** @file
+ @ingroup public_header
+ @brief The portable PortAudio API.
+*/
+
+
+#ifdef __cplusplus
+extern "C"
+{
+#endif /* __cplusplus */
+
+ 
+/** Retrieve the release number of the currently running PortAudio build,
+ eg 1900.
+*/
+int Pa_GetVersion( void );
+
+
+/** Retrieve a textual description of the current PortAudio build,
+ eg "PortAudio V19-devel 13 October 2002".
+*/
+const char* Pa_GetVersionText( void );
+
+
+/** Error codes returned by PortAudio functions.
+ Note that with the exception of paNoError, all PaErrorCodes are negative.
+*/
+
+typedef int PaError;
+typedef enum PaErrorCode
+{
+    paNoError = 0,
+
+    paNotInitialized = -10000,
+    paUnanticipatedHostError,
+    paInvalidChannelCount,
+    paInvalidSampleRate,
+    paInvalidDevice,
+    paInvalidFlag,
+    paSampleFormatNotSupported,
+    paBadIODeviceCombination,
+    paInsufficientMemory,
+    paBufferTooBig,
+    paBufferTooSmall,
+    paNullCallback,
+    paBadStreamPtr,
+    paTimedOut,
+    paInternalError,
+    paDeviceUnavailable,
+    paIncompatibleHostApiSpecificStreamInfo,
+    paStreamIsStopped,
+    paStreamIsNotStopped,
+    paInputOverflowed,
+    paOutputUnderflowed,
+    paHostApiNotFound,
+    paInvalidHostApi,
+    paCanNotReadFromACallbackStream,
+    paCanNotWriteToACallbackStream,
+    paCanNotReadFromAnOutputOnlyStream,
+    paCanNotWriteToAnInputOnlyStream,
+    paIncompatibleStreamHostApi,
+    paBadBufferPtr
+} PaErrorCode;
+
+
+/** Translate the supplied PortAudio error code into a human readable
+ message.
+*/
+const char *Pa_GetErrorText( PaError errorCode );
+
+
+/** Library initialization function - call this before using PortAudio.
+ This function initializes internal data structures and prepares underlying
+ host APIs for use.  With the exception of Pa_GetVersion(), Pa_GetVersionText(),
+ and Pa_GetErrorText(), this function MUST be called before using any other
+ PortAudio API functions.
+
+ If Pa_Initialize() is called multiple times, each successful 
+ call must be matched with a corresponding call to Pa_Terminate(). 
+ Pairs of calls to Pa_Initialize()/Pa_Terminate() may overlap, and are not 
+ required to be fully nested.
+
+ Note that if Pa_Initialize() returns an error code, Pa_Terminate() should
+ NOT be called.
+
+ @return paNoError if successful, otherwise an error code indicating the cause
+ of failure.
+
+ @see Pa_Terminate
+*/
+PaError Pa_Initialize( void );
+
+
+/** Library termination function - call this when finished using PortAudio.
+ This function deallocates all resources allocated by PortAudio since it was
+ initialized by a call to Pa_Initialize(). In cases where Pa_Initialise() has
+ been called multiple times, each call must be matched with a corresponding call
+ to Pa_Terminate(). The final matching call to Pa_Terminate() will automatically
+ close any PortAudio streams that are still open.
+
+ Pa_Terminate() MUST be called before exiting a program which uses PortAudio.
+ Failure to do so may result in serious resource leaks, such as audio devices
+ not being available until the next reboot.
+
+ @return paNoError if successful, otherwise an error code indicating the cause
+ of failure.
+ 
+ @see Pa_Initialize
+*/
+PaError Pa_Terminate( void );
+
+
+
+/** The type used to refer to audio devices. Values of this type usually
+ range from 0 to (Pa_GetDeviceCount()-1), and may also take on the PaNoDevice
+ and paUseHostApiSpecificDeviceSpecification values.
+
+ @see Pa_GetDeviceCount, paNoDevice, paUseHostApiSpecificDeviceSpecification
+*/
+typedef int PaDeviceIndex;
+
+
+/** A special PaDeviceIndex value indicating that no device is available,
+ or should be used.
+
+ @see PaDeviceIndex
+*/
+#define paNoDevice ((PaDeviceIndex)-1)
+
+
+/** A special PaDeviceIndex value indicating that the device(s) to be used
+ are specified in the host api specific stream info structure.
+
+ @see PaDeviceIndex
+*/
+#define paUseHostApiSpecificDeviceSpecification ((PaDeviceIndex)-2)
+
+
+/* Host API enumeration mechanism */
+
+/** The type used to enumerate to host APIs at runtime. Values of this type
+ range from 0 to (Pa_GetHostApiCount()-1).
+
+ @see Pa_GetHostApiCount
+*/
+typedef int PaHostApiIndex;
+
+
+/** Retrieve the number of available host APIs. Even if a host API is
+ available it may have no devices available.
+
+ @return A non-negative value indicating the number of available host APIs
+ or, a PaErrorCode (which are always negative) if PortAudio is not initialized
+ or an error is encountered.
+
+ @see PaHostApiIndex
+*/
+PaHostApiIndex Pa_GetHostApiCount( void );
+
+
+/** Retrieve the index of the default host API. The default host API will be
+ the lowest common denominator host API on the current platform and is
+ unlikely to provide the best performance.
+
+ @return A non-negative value ranging from 0 to (Pa_GetHostApiCount()-1)
+ indicating the default host API index or, a PaErrorCode (which are always
+ negative) if PortAudio is not initialized or an error is encountered.
+*/
+PaHostApiIndex Pa_GetDefaultHostApi( void );
+
+
+/** Unchanging unique identifiers for each supported host API. This type
+ is used in the PaHostApiInfo structure. The values are guaranteed to be
+ unique and to never change, thus allowing code to be written that
+ conditionally uses host API specific extensions.
+
+ New type ids will be allocated when support for a host API reaches
+ "public alpha" status, prior to that developers should use the
+ paInDevelopment type id.
+
+ @see PaHostApiInfo
+*/
+typedef enum PaHostApiTypeId
+{
+    paInDevelopment=0, /* use while developing support for a new host API */
+    paDirectSound=1,
+    paMME=2,
+    paASIO=3,
+    paSoundManager=4,
+    paCoreAudio=5,
+    paOSS=7,
+    paALSA=8,
+    paAL=9,
+    paBeOS=10,
+    paWDMKS=11,
+    paJACK=12,
+    paWASAPI=13,
+    paAudioScienceHPI=14
+} PaHostApiTypeId;
+
+
+/** A structure containing information about a particular host API. */
+
+typedef struct PaHostApiInfo
+{
+    /** this is struct version 1 */
+    int structVersion;
+    /** The well known unique identifier of this host API @see PaHostApiTypeId */
+    PaHostApiTypeId type;
+    /** A textual description of the host API for display on user interfaces. */
+    const char *name;
+
+    /**  The number of devices belonging to this host API. This field may be
+     used in conjunction with Pa_HostApiDeviceIndexToDeviceIndex() to enumerate
+     all devices for this host API.
+     @see Pa_HostApiDeviceIndexToDeviceIndex
+    */
+    int deviceCount;
+
+    /** The default input device for this host API. The value will be a
+     device index ranging from 0 to (Pa_GetDeviceCount()-1), or paNoDevice
+     if no default input device is available.
+    */
+    PaDeviceIndex defaultInputDevice;
+
+    /** The default output device for this host API. The value will be a
+     device index ranging from 0 to (Pa_GetDeviceCount()-1), or paNoDevice
+     if no default output device is available.
+    */
+    PaDeviceIndex defaultOutputDevice;
+    
+} PaHostApiInfo;
+
+
+/** Retrieve a pointer to a structure containing information about a specific
+ host Api.
+
+ @param hostApi A valid host API index ranging from 0 to (Pa_GetHostApiCount()-1)
+
+ @return A pointer to an immutable PaHostApiInfo structure describing
+ a specific host API. If the hostApi parameter is out of range or an error
+ is encountered, the function returns NULL.
+
+ The returned structure is owned by the PortAudio implementation and must not
+ be manipulated or freed. The pointer is only guaranteed to be valid between
+ calls to Pa_Initialize() and Pa_Terminate().
+*/
+const PaHostApiInfo * Pa_GetHostApiInfo( PaHostApiIndex hostApi );
+
+
+/** Convert a static host API unique identifier, into a runtime
+ host API index.
+
+ @param type A unique host API identifier belonging to the PaHostApiTypeId
+ enumeration.
+
+ @return A valid PaHostApiIndex ranging from 0 to (Pa_GetHostApiCount()-1) or,
+ a PaErrorCode (which are always negative) if PortAudio is not initialized
+ or an error is encountered.
+ 
+ The paHostApiNotFound error code indicates that the host API specified by the
+ type parameter is not available.
+
+ @see PaHostApiTypeId
+*/
+PaHostApiIndex Pa_HostApiTypeIdToHostApiIndex( PaHostApiTypeId type );
+
+
+/** Convert a host-API-specific device index to standard PortAudio device index.
+ This function may be used in conjunction with the deviceCount field of
+ PaHostApiInfo to enumerate all devices for the specified host API.
+
+ @param hostApi A valid host API index ranging from 0 to (Pa_GetHostApiCount()-1)
+
+ @param hostApiDeviceIndex A valid per-host device index in the range
+ 0 to (Pa_GetHostApiInfo(hostApi)->deviceCount-1)
+
+ @return A non-negative PaDeviceIndex ranging from 0 to (Pa_GetDeviceCount()-1)
+ or, a PaErrorCode (which are always negative) if PortAudio is not initialized
+ or an error is encountered.
+
+ A paInvalidHostApi error code indicates that the host API index specified by
+ the hostApi parameter is out of range.
+
+ A paInvalidDevice error code indicates that the hostApiDeviceIndex parameter
+ is out of range.
+ 
+ @see PaHostApiInfo
+*/
+PaDeviceIndex Pa_HostApiDeviceIndexToDeviceIndex( PaHostApiIndex hostApi,
+        int hostApiDeviceIndex );
+
+
+
+/** Structure used to return information about a host error condition.
+*/
+typedef struct PaHostErrorInfo{
+    PaHostApiTypeId hostApiType;    /**< the host API which returned the error code */
+    long errorCode;                 /**< the error code returned */
+    const char *errorText;          /**< a textual description of the error if available, otherwise a zero-length string */
+}PaHostErrorInfo;
+
+
+/** Return information about the last host error encountered. The error
+ information returned by Pa_GetLastHostErrorInfo() will never be modified
+ asynchronously by errors occurring in other PortAudio owned threads
+ (such as the thread that manages the stream callback.)
+
+ This function is provided as a last resort, primarily to enhance debugging
+ by providing clients with access to all available error information.
+
+ @return A pointer to an immutable structure constraining information about
+ the host error. The values in this structure will only be valid if a
+ PortAudio function has previously returned the paUnanticipatedHostError
+ error code.
+*/
+const PaHostErrorInfo* Pa_GetLastHostErrorInfo( void );
+
+
+
+/* Device enumeration and capabilities */
+
+/** Retrieve the number of available devices. The number of available devices
+ may be zero.
+
+ @return A non-negative value indicating the number of available devices or,
+ a PaErrorCode (which are always negative) if PortAudio is not initialized
+ or an error is encountered.
+*/
+PaDeviceIndex Pa_GetDeviceCount( void );
+
+
+/** Retrieve the index of the default input device. The result can be
+ used in the inputDevice parameter to Pa_OpenStream().
+
+ @return The default input device index for the default host API, or paNoDevice
+ if no default input device is available or an error was encountered.
+*/
+PaDeviceIndex Pa_GetDefaultInputDevice( void );
+
+
+/** Retrieve the index of the default output device. The result can be
+ used in the outputDevice parameter to Pa_OpenStream().
+
+ @return The default output device index for the default host API, or paNoDevice
+ if no default output device is available or an error was encountered.
+
+ @note
+ On the PC, the user can specify a default device by
+ setting an environment variable. For example, to use device #1.
+<pre>
+ set PA_RECOMMENDED_OUTPUT_DEVICE=1
+</pre>
+ The user should first determine the available device ids by using
+ the supplied application "pa_devs".
+*/
+PaDeviceIndex Pa_GetDefaultOutputDevice( void );
+
+
+/** The type used to represent monotonic time in seconds. PaTime is 
+ used for the fields of the PaStreamCallbackTimeInfo argument to the 
+ PaStreamCallback and as the result of Pa_GetStreamTime().
+
+ PaTime values have unspecified origin.
+     
+ @see PaStreamCallback, PaStreamCallbackTimeInfo, Pa_GetStreamTime
+*/
+typedef double PaTime;
+
+
+/** A type used to specify one or more sample formats. Each value indicates
+ a possible format for sound data passed to and from the stream callback,
+ Pa_ReadStream and Pa_WriteStream.
+
+ The standard formats paFloat32, paInt16, paInt32, paInt24, paInt8
+ and aUInt8 are usually implemented by all implementations.
+
+ The floating point representation (paFloat32) uses +1.0 and -1.0 as the
+ maximum and minimum respectively.
+
+ paUInt8 is an unsigned 8 bit format where 128 is considered "ground"
+
+ The paNonInterleaved flag indicates that audio data is passed as an array 
+ of pointers to separate buffers, one buffer for each channel. Usually,
+ when this flag is not used, audio data is passed as a single buffer with
+ all channels interleaved.
+
+ @see Pa_OpenStream, Pa_OpenDefaultStream, PaDeviceInfo
+ @see paFloat32, paInt16, paInt32, paInt24, paInt8
+ @see paUInt8, paCustomFormat, paNonInterleaved
+*/
+typedef unsigned long PaSampleFormat;
+
+
+#define paFloat32        ((PaSampleFormat) 0x00000001) /**< @see PaSampleFormat */
+#define paInt32          ((PaSampleFormat) 0x00000002) /**< @see PaSampleFormat */
+#define paInt24          ((PaSampleFormat) 0x00000004) /**< Packed 24 bit format. @see PaSampleFormat */
+#define paInt16          ((PaSampleFormat) 0x00000008) /**< @see PaSampleFormat */
+#define paInt8           ((PaSampleFormat) 0x00000010) /**< @see PaSampleFormat */
+#define paUInt8          ((PaSampleFormat) 0x00000020) /**< @see PaSampleFormat */
+#define paCustomFormat   ((PaSampleFormat) 0x00010000) /**< @see PaSampleFormat */
+
+#define paNonInterleaved ((PaSampleFormat) 0x80000000) /**< @see PaSampleFormat */
+
+/** A structure providing information and capabilities of PortAudio devices.
+ Devices may support input, output or both input and output.
+*/
+typedef struct PaDeviceInfo
+{
+    int structVersion;  /* this is struct version 2 */
+    const char *name;
+    PaHostApiIndex hostApi; /**< note this is a host API index, not a type id*/
+    
+    int maxInputChannels;
+    int maxOutputChannels;
+
+    /** Default latency values for interactive performance. */
+    PaTime defaultLowInputLatency;
+    PaTime defaultLowOutputLatency;
+    /** Default latency values for robust non-interactive applications (eg. playing sound files). */
+    PaTime defaultHighInputLatency;
+    PaTime defaultHighOutputLatency;
+
+    double defaultSampleRate;
+} PaDeviceInfo;
+
+
+/** Retrieve a pointer to a PaDeviceInfo structure containing information
+ about the specified device.
+ @return A pointer to an immutable PaDeviceInfo structure. If the device
+ parameter is out of range the function returns NULL.
+
+ @param device A valid device index in the range 0 to (Pa_GetDeviceCount()-1)
+
+ @note PortAudio manages the memory referenced by the returned pointer,
+ the client must not manipulate or free the memory. The pointer is only
+ guaranteed to be valid between calls to Pa_Initialize() and Pa_Terminate().
+
+ @see PaDeviceInfo, PaDeviceIndex
+*/
+const PaDeviceInfo* Pa_GetDeviceInfo( PaDeviceIndex device );
+
+
+/** Parameters for one direction (input or output) of a stream.
+*/
+typedef struct PaStreamParameters
+{
+    /** A valid device index in the range 0 to (Pa_GetDeviceCount()-1)
+     specifying the device to be used or the special constant
+     paUseHostApiSpecificDeviceSpecification which indicates that the actual
+     device(s) to use are specified in hostApiSpecificStreamInfo.
+     This field must not be set to paNoDevice.
+    */
+    PaDeviceIndex device;
+    
+    /** The number of channels of sound to be delivered to the
+     stream callback or accessed by Pa_ReadStream() or Pa_WriteStream().
+     It can range from 1 to the value of maxInputChannels in the
+     PaDeviceInfo record for the device specified by the device parameter.
+    */
+    int channelCount;
+
+    /** The sample format of the buffer provided to the stream callback,
+     a_ReadStream() or Pa_WriteStream(). It may be any of the formats described
+     by the PaSampleFormat enumeration.
+    */
+    PaSampleFormat sampleFormat;
+
+    /** The desired latency in seconds. Where practical, implementations should
+     configure their latency based on these parameters, otherwise they may
+     choose the closest viable latency instead. Unless the suggested latency
+     is greater than the absolute upper limit for the device implementations
+     should round the suggestedLatency up to the next practical value - ie to
+     provide an equal or higher latency than suggestedLatency wherever possible.
+     Actual latency values for an open stream may be retrieved using the
+     inputLatency and outputLatency fields of the PaStreamInfo structure
+     returned by Pa_GetStreamInfo().
+     @see default*Latency in PaDeviceInfo, *Latency in PaStreamInfo
+    */
+    PaTime suggestedLatency;
+
+    /** An optional pointer to a host api specific data structure
+     containing additional information for device setup and/or stream processing.
+     hostApiSpecificStreamInfo is never required for correct operation,
+     if not used it should be set to NULL.
+    */
+    void *hostApiSpecificStreamInfo;
+
+} PaStreamParameters;
+
+
+/** Return code for Pa_IsFormatSupported indicating success. */
+#define paFormatIsSupported (0)
+
+/** Determine whether it would be possible to open a stream with the specified
+ parameters.
+
+ @param inputParameters A structure that describes the input parameters used to
+ open a stream. The suggestedLatency field is ignored. See PaStreamParameters
+ for a description of these parameters. inputParameters must be NULL for
+ output-only streams.
+
+ @param outputParameters A structure that describes the output parameters used
+ to open a stream. The suggestedLatency field is ignored. See PaStreamParameters
+ for a description of these parameters. outputParameters must be NULL for
+ input-only streams.
+
+ @param sampleRate The required sampleRate. For full-duplex streams it is the
+ sample rate for both input and output
+
+ @return Returns 0 if the format is supported, and an error code indicating why
+ the format is not supported otherwise. The constant paFormatIsSupported is
+ provided to compare with the return value for success.
+
+ @see paFormatIsSupported, PaStreamParameters
+*/
+PaError Pa_IsFormatSupported( const PaStreamParameters *inputParameters,
+                              const PaStreamParameters *outputParameters,
+                              double sampleRate );
+
+
+
+/* Streaming types and functions */
+
+
+/**
+ A single PaStream can provide multiple channels of real-time
+ streaming audio input and output to a client application. A stream
+ provides access to audio hardware represented by one or more
+ PaDevices. Depending on the underlying Host API, it may be possible 
+ to open multiple streams using the same device, however this behavior 
+ is implementation defined. Portable applications should assume that 
+ a PaDevice may be simultaneously used by at most one PaStream.
+
+ Pointers to PaStream objects are passed between PortAudio functions that
+ operate on streams.
+
+ @see Pa_OpenStream, Pa_OpenDefaultStream, Pa_OpenDefaultStream, Pa_CloseStream,
+ Pa_StartStream, Pa_StopStream, Pa_AbortStream, Pa_IsStreamActive,
+ Pa_GetStreamTime, Pa_GetStreamCpuLoad
+
+*/
+typedef void PaStream;
+
+
+/** Can be passed as the framesPerBuffer parameter to Pa_OpenStream()
+ or Pa_OpenDefaultStream() to indicate that the stream callback will
+ accept buffers of any size.
+*/
+#define paFramesPerBufferUnspecified  (0)
+
+
+/** Flags used to control the behavior of a stream. They are passed as
+ parameters to Pa_OpenStream or Pa_OpenDefaultStream. Multiple flags may be
+ ORed together.
+
+ @see Pa_OpenStream, Pa_OpenDefaultStream
+ @see paNoFlag, paClipOff, paDitherOff, paNeverDropInput,
+  paPrimeOutputBuffersUsingStreamCallback, paPlatformSpecificFlags
+*/
+typedef unsigned long PaStreamFlags;
+
+/** @see PaStreamFlags */
+#define   paNoFlag          ((PaStreamFlags) 0)
+
+/** Disable default clipping of out of range samples.
+ @see PaStreamFlags
+*/
+#define   paClipOff         ((PaStreamFlags) 0x00000001)
+
+/** Disable default dithering.
+ @see PaStreamFlags
+*/
+#define   paDitherOff       ((PaStreamFlags) 0x00000002)
+
+/** Flag requests that where possible a full duplex stream will not discard
+ overflowed input samples without calling the stream callback. This flag is
+ only valid for full duplex callback streams and only when used in combination
+ with the paFramesPerBufferUnspecified (0) framesPerBuffer parameter. Using
+ this flag incorrectly results in a paInvalidFlag error being returned from
+ Pa_OpenStream and Pa_OpenDefaultStream.
+
+ @see PaStreamFlags, paFramesPerBufferUnspecified
+*/
+#define   paNeverDropInput  ((PaStreamFlags) 0x00000004)
+
+/** Call the stream callback to fill initial output buffers, rather than the
+ default behavior of priming the buffers with zeros (silence). This flag has
+ no effect for input-only and blocking read/write streams.
+ 
+ @see PaStreamFlags
+*/
+#define   paPrimeOutputBuffersUsingStreamCallback ((PaStreamFlags) 0x00000008)
+
+/** A mask specifying the platform specific bits.
+ @see PaStreamFlags
+*/
+#define   paPlatformSpecificFlags ((PaStreamFlags)0xFFFF0000)
+
+/**
+ Timing information for the buffers passed to the stream callback.
+
+ Time values are expressed in seconds and are synchronised with the time base used by Pa_GetStreamTime() for the associated stream.
+ 
+ @see PaStreamCallback, Pa_GetStreamTime
+*/
+typedef struct PaStreamCallbackTimeInfo{
+    PaTime inputBufferAdcTime;  /**< The time when the first sample of the input buffer was captured at the ADC input */
+    PaTime currentTime;         /**< The time when the stream callback was invoked */
+    PaTime outputBufferDacTime; /**< The time when the first sample of the output buffer will output the DAC */
+} PaStreamCallbackTimeInfo;
+
+
+/**
+ Flag bit constants for the statusFlags to PaStreamCallback.
+
+ @see paInputUnderflow, paInputOverflow, paOutputUnderflow, paOutputOverflow,
+ paPrimingOutput
+*/
+typedef unsigned long PaStreamCallbackFlags;
+
+/** In a stream opened with paFramesPerBufferUnspecified, indicates that
+ input data is all silence (zeros) because no real data is available. In a
+ stream opened without paFramesPerBufferUnspecified, it indicates that one or
+ more zero samples have been inserted into the input buffer to compensate
+ for an input underflow.
+ @see PaStreamCallbackFlags
+*/
+#define paInputUnderflow   ((PaStreamCallbackFlags) 0x00000001)
+
+/** In a stream opened with paFramesPerBufferUnspecified, indicates that data
+ prior to the first sample of the input buffer was discarded due to an
+ overflow, possibly because the stream callback is using too much CPU time.
+ Otherwise indicates that data prior to one or more samples in the
+ input buffer was discarded.
+ @see PaStreamCallbackFlags
+*/
+#define paInputOverflow    ((PaStreamCallbackFlags) 0x00000002)
+
+/** Indicates that output data (or a gap) was inserted, possibly because the
+ stream callback is using too much CPU time.
+ @see PaStreamCallbackFlags
+*/
+#define paOutputUnderflow  ((PaStreamCallbackFlags) 0x00000004)
+
+/** Indicates that output data will be discarded because no room is available.
+ @see PaStreamCallbackFlags
+*/
+#define paOutputOverflow   ((PaStreamCallbackFlags) 0x00000008)
+
+/** Some of all of the output data will be used to prime the stream, input
+ data may be zero.
+ @see PaStreamCallbackFlags
+*/
+#define paPrimingOutput    ((PaStreamCallbackFlags) 0x00000010)
+
+/**
+ Allowable return values for the PaStreamCallback.
+ @see PaStreamCallback
+*/
+typedef enum PaStreamCallbackResult
+{
+    paContinue=0,   /**< Signal that the stream should continue invoking the callback and processing audio. */
+    paComplete=1,   /**< Signal that the stream should stop invoking the callback and finish once all output samples have played. */
+    paAbort=2       /**< Signal that the stream should stop invoking the callback and finish as soon as possible. */
+} PaStreamCallbackResult;
+
+
+/**
+ Functions of type PaStreamCallback are implemented by PortAudio clients.
+ They consume, process or generate audio in response to requests from an
+ active PortAudio stream.
+
+ When a stream is running, PortAudio calls the stream callback periodically.
+ The callback function is responsible for processing buffers of audio samples 
+ passed via the input and output parameters.
+
+ The PortAudio stream callback runs at very high or real-time priority.
+ It is required to consistently meet its time deadlines. Do not allocate 
+ memory, access the file system, call library functions or call other functions 
+ from the stream callback that may block or take an unpredictable amount of
+ time to complete.
+
+ In order for a stream to maintain glitch-free operation the callback
+ must consume and return audio data faster than it is recorded and/or
+ played. PortAudio anticipates that each callback invocation may execute for 
+ a duration approaching the duration of frameCount audio frames at the stream 
+ sample rate. It is reasonable to expect to be able to utilise 70% or more of
+ the available CPU time in the PortAudio callback. However, due to buffer size 
+ adaption and other factors, not all host APIs are able to guarantee audio 
+ stability under heavy CPU load with arbitrary fixed callback buffer sizes. 
+ When high callback CPU utilisation is required the most robust behavior 
+ can be achieved by using paFramesPerBufferUnspecified as the 
+ Pa_OpenStream() framesPerBuffer parameter.
+     
+ @param input and @param output are either arrays of interleaved samples or;
+ if non-interleaved samples were requested using the paNonInterleaved sample 
+ format flag, an array of buffer pointers, one non-interleaved buffer for 
+ each channel.
+
+ The format, packing and number of channels used by the buffers are
+ determined by parameters to Pa_OpenStream().
+     
+ @param frameCount The number of sample frames to be processed by
+ the stream callback.
+
+ @param timeInfo Timestamps indicating the ADC capture time of the first sample
+ in the input buffer, the DAC output time of the first sample in the output buffer
+ and the time the callback was invoked. 
+ See PaStreamCallbackTimeInfo and Pa_GetStreamTime()
+
+ @param statusFlags Flags indicating whether input and/or output buffers
+ have been inserted or will be dropped to overcome underflow or overflow
+ conditions.
+
+ @param userData The value of a user supplied pointer passed to
+ Pa_OpenStream() intended for storing synthesis data etc.
+
+ @return
+ The stream callback should return one of the values in the
+ ::PaStreamCallbackResult enumeration. To ensure that the callback continues
+ to be called, it should return paContinue (0). Either paComplete or paAbort
+ can be returned to finish stream processing, after either of these values is
+ returned the callback will not be called again. If paAbort is returned the
+ stream will finish as soon as possible. If paComplete is returned, the stream
+ will continue until all buffers generated by the callback have been played.
+ This may be useful in applications such as soundfile players where a specific
+ duration of output is required. However, it is not necessary to utilize this
+ mechanism as Pa_StopStream(), Pa_AbortStream() or Pa_CloseStream() can also
+ be used to stop the stream. The callback must always fill the entire output
+ buffer irrespective of its return value.
+
+ @see Pa_OpenStream, Pa_OpenDefaultStream
+
+ @note With the exception of Pa_GetStreamCpuLoad() it is not permissible to call
+ PortAudio API functions from within the stream callback.
+*/
+typedef int PaStreamCallback(
+    const void *input, void *output,
+    unsigned long frameCount,
+    const PaStreamCallbackTimeInfo* timeInfo,
+    PaStreamCallbackFlags statusFlags,
+    void *userData );
+
+
+/** Opens a stream for either input, output or both.
+     
+ @param stream The address of a PaStream pointer which will receive
+ a pointer to the newly opened stream.
+     
+ @param inputParameters A structure that describes the input parameters used by
+ the opened stream. See PaStreamParameters for a description of these parameters.
+ inputParameters must be NULL for output-only streams.
+
+ @param outputParameters A structure that describes the output parameters used by
+ the opened stream. See PaStreamParameters for a description of these parameters.
+ outputParameters must be NULL for input-only streams.
+ 
+ @param sampleRate The desired sampleRate. For full-duplex streams it is the
+ sample rate for both input and output
+     
+ @param framesPerBuffer The number of frames passed to the stream callback
+ function, or the preferred block granularity for a blocking read/write stream.
+ The special value paFramesPerBufferUnspecified (0) may be used to request that
+ the stream callback will receive an optimal (and possibly varying) number of
+ frames based on host requirements and the requested latency settings.
+ Note: With some host APIs, the use of non-zero framesPerBuffer for a callback
+ stream may introduce an additional layer of buffering which could introduce
+ additional latency. PortAudio guarantees that the additional latency
+ will be kept to the theoretical minimum however, it is strongly recommended
+ that a non-zero framesPerBuffer value only be used when your algorithm
+ requires a fixed number of frames per stream callback.
+ 
+ @param streamFlags Flags which modify the behavior of the streaming process.
+ This parameter may contain a combination of flags ORed together. Some flags may
+ only be relevant to certain buffer formats.
+     
+ @param streamCallback A pointer to a client supplied function that is responsible
+ for processing and filling input and output buffers. If this parameter is NULL
+ the stream will be opened in 'blocking read/write' mode. In blocking mode,
+ the client can receive sample data using Pa_ReadStream and write sample data
+ using Pa_WriteStream, the number of samples that may be read or written
+ without blocking is returned by Pa_GetStreamReadAvailable and
+ Pa_GetStreamWriteAvailable respectively.
+
+ @param userData A client supplied pointer which is passed to the stream callback
+ function. It could for example, contain a pointer to instance data necessary
+ for processing the audio buffers. This parameter is ignored if streamCallback
+ is NULL.
+     
+ @return
+ Upon success Pa_OpenStream() returns paNoError and places a pointer to a
+ valid PaStream in the stream argument. The stream is inactive (stopped).
+ If a call to Pa_OpenStream() fails, a non-zero error code is returned (see
+ PaError for possible error codes) and the value of stream is invalid.
+
+ @see PaStreamParameters, PaStreamCallback, Pa_ReadStream, Pa_WriteStream,
+ Pa_GetStreamReadAvailable, Pa_GetStreamWriteAvailable
+*/
+PaError Pa_OpenStream( PaStream** stream,
+                       const PaStreamParameters *inputParameters,
+                       const PaStreamParameters *outputParameters,
+                       double sampleRate,
+                       unsigned long framesPerBuffer,
+                       PaStreamFlags streamFlags,
+                       PaStreamCallback *streamCallback,
+                       void *userData );
+
+
+/** A simplified version of Pa_OpenStream() that opens the default input
+ and/or output devices.
+
+ @param stream The address of a PaStream pointer which will receive
+ a pointer to the newly opened stream.
+ 
+ @param numInputChannels  The number of channels of sound that will be supplied
+ to the stream callback or returned by Pa_ReadStream. It can range from 1 to
+ the value of maxInputChannels in the PaDeviceInfo record for the default input
+ device. If 0 the stream is opened as an output-only stream.
+
+ @param numOutputChannels The number of channels of sound to be delivered to the
+ stream callback or passed to Pa_WriteStream. It can range from 1 to the value
+ of maxOutputChannels in the PaDeviceInfo record for the default output device.
+ If 0 the stream is opened as an output-only stream.
+
+ @param sampleFormat The sample format of both the input and output buffers
+ provided to the callback or passed to and from Pa_ReadStream and Pa_WriteStream.
+ sampleFormat may be any of the formats described by the PaSampleFormat
+ enumeration.
+ 
+ @param sampleRate Same as Pa_OpenStream parameter of the same name.
+ @param framesPerBuffer Same as Pa_OpenStream parameter of the same name.
+ @param streamCallback Same as Pa_OpenStream parameter of the same name.
+ @param userData Same as Pa_OpenStream parameter of the same name.
+
+ @return As for Pa_OpenStream
+
+ @see Pa_OpenStream, PaStreamCallback
+*/
+PaError Pa_OpenDefaultStream( PaStream** stream,
+                              int numInputChannels,
+                              int numOutputChannels,
+                              PaSampleFormat sampleFormat,
+                              double sampleRate,
+                              unsigned long framesPerBuffer,
+                              PaStreamCallback *streamCallback,
+                              void *userData );
+
+
+/** Closes an audio stream. If the audio stream is active it
+ discards any pending buffers as if Pa_AbortStream() had been called.
+*/
+PaError Pa_CloseStream( PaStream *stream );
+
+
+/** Functions of type PaStreamFinishedCallback are implemented by PortAudio 
+ clients. They can be registered with a stream using the Pa_SetStreamFinishedCallback
+ function. Once registered they are called when the stream becomes inactive
+ (ie once a call to Pa_StopStream() will not block).
+ A stream will become inactive after the stream callback returns non-zero,
+ or when Pa_StopStream or Pa_AbortStream is called. For a stream providing audio
+ output, if the stream callback returns paComplete, or Pa_StopStream is called,
+ the stream finished callback will not be called until all generated sample data
+ has been played.
+ 
+ @param userData The userData parameter supplied to Pa_OpenStream()
+
+ @see Pa_SetStreamFinishedCallback
+*/
+typedef void PaStreamFinishedCallback( void *userData );
+
+
+/** Register a stream finished callback function which will be called when the 
+ stream becomes inactive. See the description of PaStreamFinishedCallback for 
+ further details about when the callback will be called.
+
+ @param stream a pointer to a PaStream that is in the stopped state - if the
+ stream is not stopped, the stream's finished callback will remain unchanged 
+ and an error code will be returned.
+
+ @param streamFinishedCallback a pointer to a function with the same signature
+ as PaStreamFinishedCallback, that will be called when the stream becomes
+ inactive. Passing NULL for this parameter will un-register a previously
+ registered stream finished callback function.
+
+ @return on success returns paNoError, otherwise an error code indicating the cause
+ of the error.
+
+ @see PaStreamFinishedCallback
+*/
+PaError Pa_SetStreamFinishedCallback( PaStream *stream, PaStreamFinishedCallback* streamFinishedCallback ); 
+
+
+/** Commences audio processing.
+*/
+PaError Pa_StartStream( PaStream *stream );
+
+
+/** Terminates audio processing. It waits until all pending
+ audio buffers have been played before it returns.
+*/
+PaError Pa_StopStream( PaStream *stream );
+
+
+/** Terminates audio processing immediately without waiting for pending
+ buffers to complete.
+*/
+PaError Pa_AbortStream( PaStream *stream );
+
+
+/** Determine whether the stream is stopped.
+ A stream is considered to be stopped prior to a successful call to
+ Pa_StartStream and after a successful call to Pa_StopStream or Pa_AbortStream.
+ If a stream callback returns a value other than paContinue the stream is NOT
+ considered to be stopped.
+
+ @return Returns one (1) when the stream is stopped, zero (0) when
+ the stream is running or, a PaErrorCode (which are always negative) if
+ PortAudio is not initialized or an error is encountered.
+
+ @see Pa_StopStream, Pa_AbortStream, Pa_IsStreamActive
+*/
+PaError Pa_IsStreamStopped( PaStream *stream );
+
+
+/** Determine whether the stream is active.
+ A stream is active after a successful call to Pa_StartStream(), until it
+ becomes inactive either as a result of a call to Pa_StopStream() or
+ Pa_AbortStream(), or as a result of a return value other than paContinue from
+ the stream callback. In the latter case, the stream is considered inactive
+ after the last buffer has finished playing.
+
+ @return Returns one (1) when the stream is active (ie playing or recording
+ audio), zero (0) when not playing or, a PaErrorCode (which are always negative)
+ if PortAudio is not initialized or an error is encountered.
+
+ @see Pa_StopStream, Pa_AbortStream, Pa_IsStreamStopped
+*/
+PaError Pa_IsStreamActive( PaStream *stream );
+
+
+
+/** A structure containing unchanging information about an open stream.
+ @see Pa_GetStreamInfo
+*/
+
+typedef struct PaStreamInfo
+{
+    /** this is struct version 1 */
+    int structVersion;
+
+    /** The input latency of the stream in seconds. This value provides the most
+     accurate estimate of input latency available to the implementation. It may
+     differ significantly from the suggestedLatency value passed to Pa_OpenStream().
+     The value of this field will be zero (0.) for output-only streams.
+     @see PaTime
+    */
+    PaTime inputLatency;
+
+    /** The output latency of the stream in seconds. This value provides the most
+     accurate estimate of output latency available to the implementation. It may
+     differ significantly from the suggestedLatency value passed to Pa_OpenStream().
+     The value of this field will be zero (0.) for input-only streams.
+     @see PaTime
+    */
+    PaTime outputLatency;
+
+    /** The sample rate of the stream in Hertz (samples per second). In cases
+     where the hardware sample rate is inaccurate and PortAudio is aware of it,
+     the value of this field may be different from the sampleRate parameter
+     passed to Pa_OpenStream(). If information about the actual hardware sample
+     rate is not available, this field will have the same value as the sampleRate
+     parameter passed to Pa_OpenStream().
+    */
+    double sampleRate;
+    
+} PaStreamInfo;
+
+
+/** Retrieve a pointer to a PaStreamInfo structure containing information
+ about the specified stream.
+ @return A pointer to an immutable PaStreamInfo structure. If the stream
+ parameter is invalid, or an error is encountered, the function returns NULL.
+
+ @param stream A pointer to an open stream previously created with Pa_OpenStream.
+
+ @note PortAudio manages the memory referenced by the returned pointer,
+ the client must not manipulate or free the memory. The pointer is only
+ guaranteed to be valid until the specified stream is closed.
+
+ @see PaStreamInfo
+*/
+const PaStreamInfo* Pa_GetStreamInfo( PaStream *stream );
+
+
+/** Returns the current time in seconds for a stream according to the same clock used
+ to generate callback PaStreamCallbackTimeInfo timestamps. The time values are
+ monotonically increasing and have unspecified origin. 
+ 
+ Pa_GetStreamTime returns valid time values for the entire life of the stream,
+ from when the stream is opened until it is closed. Starting and stopping the stream
+ does not affect the passage of time returned by Pa_GetStreamTime.
+
+ This time may be used for synchronizing other events to the audio stream, for 
+ example synchronizing audio to MIDI.
+                                        
+ @return The stream's current time in seconds, or 0 if an error occurred.
+
+ @see PaTime, PaStreamCallback, PaStreamCallbackTimeInfo
+*/
+PaTime Pa_GetStreamTime( PaStream *stream );
+
+
+/** Retrieve CPU usage information for the specified stream.
+ The "CPU Load" is a fraction of total CPU time consumed by a callback stream's
+ audio processing routines including, but not limited to the client supplied
+ stream callback. This function does not work with blocking read/write streams.
+
+ This function may be called from the stream callback function or the
+ application.
+     
+ @return
+ A floating point value, typically between 0.0 and 1.0, where 1.0 indicates
+ that the stream callback is consuming the maximum number of CPU cycles possible
+ to maintain real-time operation. A value of 0.5 would imply that PortAudio and
+ the stream callback was consuming roughly 50% of the available CPU time. The
+ return value may exceed 1.0. A value of 0.0 will always be returned for a
+ blocking read/write stream, or if an error occurs.
+*/
+double Pa_GetStreamCpuLoad( PaStream* stream );
+
+
+/** Read samples from an input stream. The function doesn't return until
+ the entire buffer has been filled - this may involve waiting for the operating
+ system to supply the data.
+
+ @param stream A pointer to an open stream previously created with Pa_OpenStream.
+ 
+ @param buffer A pointer to a buffer of sample frames. The buffer contains
+ samples in the format specified by the inputParameters->sampleFormat field
+ used to open the stream, and the number of channels specified by
+ inputParameters->numChannels. If non-interleaved samples were requested using
+ the paNonInterleaved sample format flag, buffer is a pointer to the first element 
+ of an array of buffer pointers, one non-interleaved buffer for each channel.
+
+ @param frames The number of frames to be read into buffer. This parameter
+ is not constrained to a specific range, however high performance applications
+ will want to match this parameter to the framesPerBuffer parameter used
+ when opening the stream.
+
+ @return On success PaNoError will be returned, or PaInputOverflowed if input
+ data was discarded by PortAudio after the previous call and before this call.
+*/
+PaError Pa_ReadStream( PaStream* stream,
+                       void *buffer,
+                       unsigned long frames );
+
+
+/** Write samples to an output stream. This function doesn't return until the
+ entire buffer has been consumed - this may involve waiting for the operating
+ system to consume the data.
+
+ @param stream A pointer to an open stream previously created with Pa_OpenStream.
+
+ @param buffer A pointer to a buffer of sample frames. The buffer contains
+ samples in the format specified by the outputParameters->sampleFormat field
+ used to open the stream, and the number of channels specified by
+ outputParameters->numChannels. If non-interleaved samples were requested using
+ the paNonInterleaved sample format flag, buffer is a pointer to the first element 
+ of an array of buffer pointers, one non-interleaved buffer for each channel.
+
+ @param frames The number of frames to be written from buffer. This parameter
+ is not constrained to a specific range, however high performance applications
+ will want to match this parameter to the framesPerBuffer parameter used
+ when opening the stream.
+
+ @return On success PaNoError will be returned, or paOutputUnderflowed if
+ additional output data was inserted after the previous call and before this
+ call.
+*/
+PaError Pa_WriteStream( PaStream* stream,
+                        const void *buffer,
+                        unsigned long frames );
+
+
+/** Retrieve the number of frames that can be read from the stream without
+ waiting.
+
+ @return Returns a non-negative value representing the maximum number of frames
+ that can be read from the stream without blocking or busy waiting or, a
+ PaErrorCode (which are always negative) if PortAudio is not initialized or an
+ error is encountered.
+*/
+signed long Pa_GetStreamReadAvailable( PaStream* stream );
+
+
+/** Retrieve the number of frames that can be written to the stream without
+ waiting.
+
+ @return Returns a non-negative value representing the maximum number of frames
+ that can be written to the stream without blocking or busy waiting or, a
+ PaErrorCode (which are always negative) if PortAudio is not initialized or an
+ error is encountered.
+*/
+signed long Pa_GetStreamWriteAvailable( PaStream* stream );
+
+
+/* Miscellaneous utilities */
+
+
+/** Retrieve the size of a given sample format in bytes.
+
+ @return The size in bytes of a single sample in the specified format,
+ or paSampleFormatNotSupported if the format is not supported.
+*/
+PaError Pa_GetSampleSize( PaSampleFormat format );
+
+
+/** Put the caller to sleep for at least 'msec' milliseconds. This function is
+ provided only as a convenience for authors of portable code (such as the tests
+ and examples in the PortAudio distribution.)
+
+ The function may sleep longer than requested so don't rely on this for accurate
+ musical timing.
+*/
+void Pa_Sleep( long msec );
+
+
+
+#ifdef __cplusplus
+}
+#endif /* __cplusplus */
+#endif /* PORTAUDIO_H */