Object pascal examples for recording and playing audio with portaudio. (#1271)

The recording example can be used for speech recognition while the playing example can be used for text to speech.

The portaudio wrapper for object pascal is copied from
https://github.com/UltraStar-Deluxe/USDX/blob/master/src/lib/portaudio/portaudio.pas

+test-record
+test-play

+# Introduction
+
+[portaudio.pas](./portaudio.pas)
+requires that the portaudio library is installed on your system.
+
+
+On macOS, you can use
+
+```bash
+brew install portaudio
+```
+
+and it will install `portaudio` into `/usr/local/Cellar/portaudio/19.7.0`.

+#!/usr/bin/env bash
+
+set -ex
+
+SCRIPT_DIR=$( cd -- "$( dirname -- "${BASH_SOURCE[0]}" )" &> /dev/null && pwd )
+SHERPA_ONNX_DIR=$(cd $SCRIPT_DIR/../.. && pwd)
+
+echo "SHERPA_ONNX_DIR: $SHERPA_ONNX_DIR"
+
+if [[ ! -f ../../build/install/lib/libsherpa-onnx-c-api.dylib  && ! -f ../../build/install/lib/libsherpa-onnx-c-api.so && ! -f ../../build/install/lib/sherpa-onnx-c-api.dll ]]; then
+  mkdir -p ../../build
+  pushd ../../build
+  cmake \
+    -DCMAKE_INSTALL_PREFIX=./install \
+    -DSHERPA_ONNX_ENABLE_PYTHON=OFF \
+    -DSHERPA_ONNX_ENABLE_TESTS=OFF \
+    -DSHERPA_ONNX_ENABLE_CHECK=OFF \
+    -DBUILD_SHARED_LIBS=ON \
+    -DSHERPA_ONNX_ENABLE_PORTAUDIO=OFF \
+    ..
+
+  cmake --build . --target install --config Release
+  popd
+fi
+
+fpc \
+  -g \
+  -dSHERPA_ONNX_USE_SHARED_LIBS \
+  -Fu$SHERPA_ONNX_DIR/sherpa-onnx/pascal-api \
+  -Fl$SHERPA_ONNX_DIR/build/install/lib \
+  -Fl/usr/local/Cellar/portaudio/19.7.0/lib \
+  ./test-play.pas
+
+export LD_LIBRARY_PATH=$SHERPA_ONNX_DIR/build/install/lib:$LD_LIBRARY_PATH
+export DYLD_LIBRARY_PATH=$SHERPA_ONNX_DIR/build/install/lib:$DYLD_LIBRARY_PATH
+
+./test-play

+#!/usr/bin/env bash
+
+set -ex
+
+SCRIPT_DIR=$( cd -- "$( dirname -- "${BASH_SOURCE[0]}" )" &> /dev/null && pwd )
+SHERPA_ONNX_DIR=$(cd $SCRIPT_DIR/../.. && pwd)
+
+echo "SHERPA_ONNX_DIR: $SHERPA_ONNX_DIR"
+
+if [[ ! -f ../../build/install/lib/libsherpa-onnx-c-api.dylib  && ! -f ../../build/install/lib/libsherpa-onnx-c-api.so && ! -f ../../build/install/lib/sherpa-onnx-c-api.dll ]]; then
+  mkdir -p ../../build
+  pushd ../../build
+  cmake \
+    -DCMAKE_INSTALL_PREFIX=./install \
+    -DSHERPA_ONNX_ENABLE_PYTHON=OFF \
+    -DSHERPA_ONNX_ENABLE_TESTS=OFF \
+    -DSHERPA_ONNX_ENABLE_CHECK=OFF \
+    -DBUILD_SHARED_LIBS=ON \
+    -DSHERPA_ONNX_ENABLE_PORTAUDIO=OFF \
+    ..
+
+  cmake --build . --target install --config Release
+  popd
+fi
+
+fpc \
+  -g \
+  -dSHERPA_ONNX_USE_SHARED_LIBS \
+  -Fu$SHERPA_ONNX_DIR/sherpa-onnx/pascal-api \
+  -Fl$SHERPA_ONNX_DIR/build/install/lib \
+  -Fl/usr/local/Cellar/portaudio/19.7.0/lib \
+  ./test-record.pas
+
+export LD_LIBRARY_PATH=$SHERPA_ONNX_DIR/build/install/lib:$LD_LIBRARY_PATH
+export DYLD_LIBRARY_PATH=$SHERPA_ONNX_DIR/build/install/lib:$DYLD_LIBRARY_PATH
+
+./test-record

+{ Copyright (c)  2024  Xiaomi Corporation }
+{
+This file shows how to use portaudio for playing.
+
+}
+program main;
+
+{$mode objfpc}{$H+}
+
+
+uses
+  portaudio,
+  sherpa_onnx,
+  dos,
+  ctypes,
+  SysUtils;
+
+var
+  Version: String;
+  EnvStr: String;
+  Status: Integer;
+  NumDevices: Integer;
+  DeviceIndex: Integer;
+  DeviceInfo: PPaDeviceInfo;
+  I: Integer;
+  Param: TPaStreamParameters;
+  Stream: PPaStream;
+  Wave: TSherpaOnnxWave;
+
+  Buffer: TSherpaOnnxCircularBuffer;
+
+function PlayCallback(
+      input: Pointer; output: Pointer;
+      frameCount: culong;
+      timeInfo: PPaStreamCallbackTimeInfo;
+      statusFlags: TPaStreamCallbackFlags;
+      userData: Pointer ): cint; cdecl;
+var
+  Samples: TSherpaOnnxSamplesArray;
+  I: Integer;
+begin
+  if Buffer.Size >= frameCount then
+    begin
+      Samples := Buffer.Get(Buffer.Head, FrameCount);
+      Buffer.Pop(FrameCount);
+    end
+  else
+    begin
+      Samples := Buffer.Get(Buffer.Head, Buffer.Size);
+      Buffer.Pop(Buffer.Size);
+      SetLength(Samples, frameCount);
+    end;
+  for I := 0 to frameCount - 1 do
+    pcfloat(output)[I] := Samples[I];
+
+  if Buffer.Size > 0 then
+    Result := paContinue
+  else
+    Result := paComplete;
+end;
+
+
+
+begin
+  Version := String(Pa_GetVersionText);
+  WriteLn('Version is ', Version);
+  Status := Pa_Initialize;
+  if Status <> paNoError then
+    begin
+      WriteLn('Failed to initialize portaudio, ', Pa_GetErrorText(Status));
+      Exit;
+    end;
+
+  NumDevices := Pa_GetDeviceCount;
+  WriteLn('Num devices: ', NumDevices);
+
+  DeviceIndex := Pa_GetDefaultOutputDevice;
+
+  if DeviceIndex = paNoDevice then
+    begin
+      WriteLn('No default output device found');
+      Pa_Terminate;
+      Exit;
+    end;
+
+  EnvStr := GetEnv('SHERPA_ONNX_MIC_DEVICE');
+  if EnvStr <> '' then
+    begin
+      DeviceIndex := StrToIntDef(EnvStr, DeviceIndex);
+      WriteLn('Use device index from environment variable SHERPA_ONNX_MIC_DEVICE: ', EnvStr);
+    end;
+
+  for I := 0 to (NumDevices - 1) do
+    begin
+      DeviceInfo := Pa_GetDeviceInfo(I);
+      if I = DeviceIndex then
+        { WriteLn(Format(' * %d %s', [I, DeviceInfo^.Name])) }
+        WriteLn(Format(' * %d %s', [I, AnsiString(DeviceInfo^.Name)]))
+      else
+        WriteLn(Format('   %d %s', [I, AnsiString(DeviceInfo^.Name)]));
+    end;
+
+  WriteLn('Use device ', DeviceIndex);
+  WriteLn(' Name ', Pa_GetDeviceInfo(DeviceIndex)^.Name);
+  WriteLn(' Max output channels ', Pa_GetDeviceInfo(DeviceIndex)^.MaxOutputChannels);
+
+  Wave := SherpaOnnxReadWave('./record.wav');
+  if Wave.Samples = nil then
+    begin
+      WriteLn('Failed to read ./record.wav');
+      Pa_Terminate;
+      Exit;
+    end;
+
+  Initialize(Param);
+  Param.Device := DeviceIndex;
+  Param.ChannelCount := 1;
+  Param.SampleFormat := paFloat32;
+  param.SuggestedLatency := Pa_GetDeviceInfo(DeviceIndex)^.DefaultHighOutputLatency;
+  param.HostApiSpecificStreamInfo := nil;
+
+  Buffer := TSherpaOnnxCircularBuffer.Create(Length(Wave.Samples));
+  Buffer.Push(Wave.Samples);
+
+  Status := Pa_OpenStream(stream, nil, @Param, Wave.SampleRate, paFramesPerBufferUnspecified, paNoFlag,
+    PPaStreamCallback(@PlayCallback), nil);
+
+  if Status <> paNoError then
+    begin
+      WriteLn('Failed to open stream, ', Pa_GetErrorText(Status));
+      Pa_Terminate;
+      Exit;
+    end;
+
+  Status := Pa_StartStream(stream);
+  if Status <> paNoError then
+    begin
+      WriteLn('Failed to start stream, ', Pa_GetErrorText(Status));
+      Pa_Terminate;
+      Exit;
+    end;
+
+  while Buffer.Size > 0 do
+    Pa_Sleep(100);  {sleep for 0.1 second }
+
+  Status := Pa_CloseStream(stream);
+  if Status <> paNoError then
+    begin
+      WriteLn('Failed to close stream, ', Pa_GetErrorText(Status));
+      Exit;
+    end;
+
+  Status := Pa_Terminate;
+  if Status <> paNoError then
+    begin
+      WriteLn('Failed to deinitialize portaudio, ', Pa_GetErrorText(Status));
+      Exit;
+    end;
+end.
+

+{ Copyright (c)  2024  Xiaomi Corporation }
+{
+This file shows how to use portaudio for recording.
+
+It records for 10 seconds and saves the audio samples to ./record.wav
+}
+program main;
+
+{$mode objfpc}
+
+uses
+  portaudio,
+  sherpa_onnx,
+  dos,
+  ctypes,
+  SysUtils;
+
+var
+  Version: String;
+  EnvStr: String;
+  Status: Integer;
+  NumDevices: Integer;
+  DeviceIndex: Integer;
+  DeviceInfo: PPaDeviceInfo;
+  I: Integer;
+  Param: TPaStreamParameters;
+  SampleRate: Double;
+  Stream: PPaStream;
+
+  Buffer: TSherpaOnnxCircularBuffer;
+  AllSamples: TSherpaOnnxSamplesArray;
+
+function RecordCallback(
+      input: Pointer; output: Pointer;
+      frameCount: culong;
+      timeInfo: PPaStreamCallbackTimeInfo;
+      statusFlags: TPaStreamCallbackFlags;
+      userData: Pointer ): cint; cdecl;
+begin
+  Buffer.Push(pcfloat(input), frameCount);
+  Result := paContinue;
+end;
+
+
+
+begin
+  Version := String(Pa_GetVersionText);
+  WriteLn('Version is ', Version);
+  Status := Pa_Initialize;
+  if Status <> paNoError then
+    begin
+      WriteLn('Failed to initialize portaudio, ', Pa_GetErrorText(Status));
+      Exit;
+    end;
+
+  NumDevices := Pa_GetDeviceCount;
+  WriteLn('Num devices: ', NumDevices);
+
+  DeviceIndex := Pa_GetDefaultInputDevice;
+
+  if DeviceIndex = paNoDevice then
+    begin
+      WriteLn('No default input device found');
+      Pa_Terminate;
+      Exit;
+    end;
+
+  EnvStr := GetEnv('SHERPA_ONNX_MIC_DEVICE');
+  if EnvStr <> '' then
+    begin
+      DeviceIndex := StrToIntDef(EnvStr, DeviceIndex);
+      WriteLn('Use device index from environment variable SHERPA_ONNX_MIC_DEVICE: ', EnvStr);
+    end;
+
+  for I := 0 to (NumDevices - 1) do
+    begin
+      DeviceInfo := Pa_GetDeviceInfo(I);
+      if I = DeviceIndex then
+        { WriteLn(Format(' * %d %s', [I, DeviceInfo^.Name])) }
+        WriteLn(Format(' * %d %s', [I, AnsiString(DeviceInfo^.Name)]))
+      else
+        WriteLn(Format('   %d %s', [I, AnsiString(DeviceInfo^.Name)]));
+    end;
+
+  WriteLn('Use device ', DeviceIndex);
+  WriteLn(' Name ', Pa_GetDeviceInfo(DeviceIndex)^.Name);
+  WriteLn(' Max input channels ', Pa_GetDeviceInfo(DeviceIndex)^.MaxInputChannels);
+
+  Initialize(Param);
+  Param.Device := DeviceIndex;
+  Param.ChannelCount := 1;
+  Param.SampleFormat := paFloat32;
+  param.SuggestedLatency := Pa_GetDeviceInfo(DeviceIndex)^.DefaultHighInputLatency;
+  param.HostApiSpecificStreamInfo := nil;
+
+  SampleRate := 48000;
+  Buffer := TSherpaOnnxCircularBuffer.Create(Round(SampleRate) * 20);
+
+  Status := Pa_OpenStream(stream, @Param, nil, SampleRate, paFramesPerBufferUnspecified, paNoFlag,
+    PPaStreamCallback(@RecordCallback), nil);
+
+  if Status <> paNoError then
+    begin
+      WriteLn('Failed to open stream, ', Pa_GetErrorText(Status));
+      Pa_Terminate;
+      Exit;
+    end;
+
+  Status := Pa_StartStream(stream);
+  if Status <> paNoError then
+    begin
+      WriteLn('Failed to start stream, ', Pa_GetErrorText(Status));
+      Pa_Terminate;
+      Exit;
+    end;
+
+  WriteLn('Please speak! It will exit after 10 seconds.');
+  Pa_Sleep(10000);  {sleep for 10 seconds }
+
+  Status := Pa_CloseStream(stream);
+  if Status <> paNoError then
+    begin
+      WriteLn('Failed to close stream, ', Pa_GetErrorText(Status));
+      Exit;
+    end;
+
+  AllSamples := Buffer.Get(0, Buffer.Size);
+
+  SherpaOnnxWriteWave('record.wav', AllSamples, Round(SampleRate));
+  WriteLn('Saved to record.wav');
+
+  Status := Pa_Terminate;
+  if Status <> paNoError then
+    begin
+      WriteLn('Failed to deinitialize portaudio, ', Pa_GetErrorText(Status));
+      Exit;
+    end;
+end.
+

@@ -5,3 +5,7 @@ This directory contains APIs for [Object Pascal](https://en.wikipedia.org/wiki/O
 Please see
 https://github.com/k2-fsa/sherpa-onnx/tree/master/pascal-api-examples
 for usages.
+
+[portaudio.pas](./portaudio.pas)
+is copied from
+https://github.com/UltraStar-Deluxe/USDX/blob/master/src/lib/portaudio/portaudio.pas

+{
+This file is copied from
+https://github.com/UltraStar-Deluxe/USDX/blob/master/src/lib/portaudio/portaudio.pas
+}
+{*
+ * $Id: portaudio.h,v 1.7 2007/08/16 20:45:34 richardash1981 Exp $
+ * 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
+ @brief The PortAudio API.
+*}
+
+unit portaudio;
+
+{$IFDEF FPC}
+  {$PACKENUM 4}    (* use 4-byte enums *)
+  {$PACKRECORDS C} (* C/C++-compatible record packing *)
+  {$MODE DELPHI }
+{$ELSE}
+  {$MINENUMSIZE 4} (* use 4-byte enums *)
+{$ENDIF}
+
+interface
+
+uses
+  ctypes;
+
+const
+{$IF Defined(MSWINDOWS)}
+  LibName = 'portaudio_x86.dll';
+{$ELSEIF Defined(UNIX)}
+  LibName = 'portaudio';
+  {$LINKLIB portaudio}
+{$IFEND}
+
+{** Retrieve the release number of the currently running PortAudio build,
+ eg 1900.
+*}
+function Pa_GetVersion(): cint; cdecl; external LibName;
+
+
+{** Retrieve a textual description of the current PortAudio build,
+ eg "PortAudio V19-devel 13 October 2002".
+*}
+function Pa_GetVersionText(): PChar; cdecl; external LibName;
+
+
+{** Error codes returned by PortAudio functions.
+ Note that with the exception of paNoError, all PaErrorCodes are negative.
+*}
+
+type TPaError = cint;
+type TPaErrorCode = {enum}cint; const
+{enum_begin PaErrorCode}
+    paNoError = 0;
+
+    paNotInitialized = -10000;
+    paUnanticipatedHostError                = (paNotInitialized+ 1);
+    paInvalidChannelCount                   = (paNotInitialized+ 2);
+    paInvalidSampleRate                     = (paNotInitialized+ 3);
+    paInvalidDevice                         = (paNotInitialized+ 4);
+    paInvalidFlag                           = (paNotInitialized+ 5);
+    paSampleFormatNotSupported              = (paNotInitialized+ 6);
+    paBadIODeviceCombination                = (paNotInitialized+ 7);
+    paInsufficientMemory                    = (paNotInitialized+ 8);
+    paBufferTooBig                          = (paNotInitialized+ 9);
+    paBufferTooSmall                        = (paNotInitialized+10);
+    paNullCallback                          = (paNotInitialized+11);
+    paBadStreamPtr                          = (paNotInitialized+12);
+    paTimedOut                              = (paNotInitialized+13);
+    paInternalError                         = (paNotInitialized+14);
+    paDeviceUnavailable                     = (paNotInitialized+15);
+    paIncompatibleHostApiSpecificStreamInfo = (paNotInitialized+16);
+    paStreamIsStopped                       = (paNotInitialized+17);
+    paStreamIsNotStopped                    = (paNotInitialized+18);
+    paInputOverflowed                       = (paNotInitialized+19);
+    paOutputUnderflowed                     = (paNotInitialized+20);
+    paHostApiNotFound                       = (paNotInitialized+21); // The notes below are from the 
+    paInvalidHostApi                        = (paNotInitialized+22); // original file portaudio.h
+    paCanNotReadFromACallbackStream         = (paNotInitialized+23); {**< @todo review error code name *}
+    paCanNotWriteToACallbackStream          = (paNotInitialized+24); {**< @todo review error code name *}
+    paCanNotReadFromAnOutputOnlyStream      = (paNotInitialized+25); {**< @todo review error code name *}
+    paCanNotWriteToAnInputOnlyStream        = (paNotInitialized+26); {**< @todo review error code name *}
+    paIncompatibleStreamHostApi             = (paNotInitialized+27);
+    paBadBufferPtr                          = (paNotInitialized+28);
+{enum_end PaErrorCode}
+
+
+{** Translate the supplied PortAudio error code into a human readable
+ message.
+*}
+function Pa_GetErrorText( errorCode: TPaError ): PChar; cdecl; external LibName;
+
+
+{** Library initialization function - call this before using PortAudio.
+ This function initialises 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
+*}
+function Pa_Initialize(): TPaError; cdecl; external LibName;
+
+
+{** Library termination function - call this when finished using PortAudio.
+ This function deallocates all resources allocated by PortAudio since it was
+ initializied 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
+*}
+function Pa_Terminate(): TPaError; cdecl; external LibName;
+
+
+
+{** 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
+*}
+type TPaDeviceIndex = cint;
+
+
+{** A special PaDeviceIndex value indicating that no device is available,
+ or should be used.
+
+ @see PaDeviceIndex
+*}
+const paNoDevice = TPaDeviceIndex(-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
+*}
+const paUseHostApiSpecificDeviceSpecification = TPaDeviceIndex(-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
+*}
+type TPaHostApiIndex = cint;
+
+{** 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
+*}
+function Pa_GetHostApiCount(): TPaHostApiIndex; cdecl; external LibName;
+
+
+{** 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.
+*}
+function Pa_GetDefaultHostApi(): TPaHostApiIndex; cdecl; external LibName;
+
+
+{** 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
+*}
+type TPaHostApiTypeId = {enum}cint; const
+{enum_begin 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;
+{enum_end PaHostApiTypeId}
+
+{** A structure containing information about a particular host API. *}
+
+type
+  PPaHostApiInfo = ^TPaHostApiInfo;
+  TPaHostApiInfo = record
+      {** this is struct version 1 *}
+      structVersion: cint;
+      {** The well known unique identifier of this host API @see PaHostApiTypeId *}
+      _type: TPaHostApiTypeId;
+      {** A textual description of the host API for display on user interfaces. *}
+      name: PChar;
+
+      {**  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
+      *}
+      deviceCount: cint;
+
+      {** 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.
+      *}
+      defaultInputDevice: TPaDeviceIndex;
+
+      {** 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.
+      *}
+      defaultOutputDevice: TPaDeviceIndex;
+  end;
+
+
+{** 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().
+*}
+function Pa_GetHostApiInfo( hostApi: TPaHostApiIndex ): PPaHostApiInfo; cdecl; external LibName;
+
+
+{** 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
+*}
+function Pa_HostApiTypeIdToHostApiIndex( _type: TPaHostApiTypeId ): TPaHostApiIndex; cdecl; external LibName;
+
+
+{** 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
+*}
+function Pa_HostApiDeviceIndexToDeviceIndex( hostApi: TPaHostApiIndex;
+        hostApiDeviceIndex: cint ): TPaDeviceIndex; cdecl; external LibName;
+
+
+
+{** Structure used to return information about a host error condition.
+*}
+type
+  PPaHostErrorInfo = ^TPaHostErrorInfo;
+  TPaHostErrorInfo = record
+      hostApiType: TPaHostApiTypeId;    {**< the host API which returned the error code *}
+      errorCode: clong;                 {**< the error code returned *}
+      errorText: PChar;                 {**< a textual description of the error if available, otherwise a zero-length string *}
+  end;
+
+
+{** Return information about the last host error encountered. The error
+ information returned by Pa_GetLastHostErrorInfo() will never be modified
+ asyncronously 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 constaining 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.
+*}
+function Pa_GetLastHostErrorInfo(): PPaHostErrorInfo; cdecl; external LibName;
+
+
+
+{* 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.
+*}
+function Pa_GetDeviceCount(): TPaDeviceIndex; cdecl; external LibName;
+
+
+{** 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.
+*}
+function Pa_GetDefaultInputDevice(): TPaDeviceIndex; cdecl; external LibName;
+
+
+{** 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 defualt 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".
+*}
+function Pa_GetDefaultOutputDevice(): TPaDeviceIndex; cdecl; external LibName;
+
+
+{** The type used to represent monotonic time in seconds that can be used
+ for syncronisation. The type is used for the outTime argument to the
+ PaStreamCallback and as the result of Pa_GetStreamTime().
+     
+ @see PaStreamCallback, Pa_GetStreamTime
+*}
+type TPaTime = cdouble;
+
+
+{** 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 a multichannel buffer is passed
+ as a set of non-interleaved pointers.
+
+ @see Pa_OpenStream, Pa_OpenDefaultStream, PaDeviceInfo
+ @see paFloat32, paInt16, paInt32, paInt24, paInt8
+ @see paUInt8, paCustomFormat, paNonInterleaved
+*}
+type TPaSampleFormat = culong;
+const
+  paFloat32        = TPaSampleFormat($00000001); {**< @see PaSampleFormat *}
+  paInt32          = TPaSampleFormat($00000002); {**< @see PaSampleFormat *}
+  paInt24          = TPaSampleFormat($00000004); {**< Packed 24 bit format. @see PaSampleFormat *}
+  paInt16          = TPaSampleFormat($00000008); {**< @see PaSampleFormat *}
+  paInt8           = TPaSampleFormat($00000010); {**< @see PaSampleFormat *}
+  paUInt8          = TPaSampleFormat($00000020); {**< @see PaSampleFormat *}
+  paCustomFormat   = TPaSampleFormat($00010000); {**< @see PaSampleFormat *}
+  paNonInterleaved = TPaSampleFormat($80000000);
+
+{** A structure providing information and capabilities of PortAudio devices.
+ Devices may support input, output or both input and output.
+*}
+type
+  PPaDeviceInfo = ^TPaDeviceInfo;
+  TPaDeviceInfo = record
+      structVersion: cint;  {* this is struct version 2 *}
+      name: PChar;
+      hostApi: TPaHostApiIndex; {* note this is a host API index, not a type id*}
+
+      maxInputChannels: cint;
+      maxOutputChannels: cint;
+
+      {* Default latency values for interactive performance. *}
+      defaultLowInputLatency: TPaTime;
+      defaultLowOutputLatency: TPaTime;
+      {* Default latency values for robust non-interactive applications (eg. playing sound files). *}
+      defaultHighInputLatency: TPaTime;
+      defaultHighOutputLatency: TPaTime;
+
+      defaultSampleRate: cdouble;
+  end;
+
+
+{** 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
+*}
+function Pa_GetDeviceInfo( device: TPaDeviceIndex ): PPaDeviceInfo; cdecl; external LibName;
+
+
+{** Parameters for one direction (input or output) of a stream.
+*}
+type
+  PPaStreamParameters = ^TPaStreamParameters;
+  TPaStreamParameters = record
+      {** 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.
+      *}
+      device: TPaDeviceIndex;
+
+      {** 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.
+      *}
+      channelCount: cint;
+
+      {** 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.
+      *}
+      sampleFormat: TPaSampleFormat;
+
+      {** 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 practial value - ie to
+       provide an equal or higher latency than suggestedLatency wherever possibe.
+       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
+      *}
+      suggestedLatency: TPaTime;
+
+      {** 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.
+      *}
+      hostApiSpecificStreamInfo: Pointer;
+  end;
+
+
+{** Return code for Pa_IsFormatSupported indicating success. *}
+const 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
+*}
+function Pa_IsFormatSupported( inputParameters: PPaStreamParameters;
+                              outputParameters: PPaStreamParameters;
+                              sampleRate: cdouble ): TPaError; cdecl; external LibName;
+
+
+
+{* 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
+
+*}
+type
+  PPaStream = Pointer;
+
+{** 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.
+*}
+const 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
+*}
+type TPaStreamFlags = culong;
+
+{** @see PaStreamFlags *}
+const   paNoFlag          = TPaStreamFlags(0);
+
+{** Disable default clipping of out of range samples.
+ @see PaStreamFlags
+*}
+const   paClipOff         = TPaStreamFlags($00000001);
+
+{** Disable default dithering.
+ @see PaStreamFlags
+*}
+const   paDitherOff       = TPaStreamFlags($00000002);
+
+{** 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
+*}
+const   paNeverDropInput  = TPaStreamFlags($00000004);
+
+{** 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
+*}
+const   paPrimeOutputBuffersUsingStreamCallback = TPaStreamFlags($00000008);
+
+{** A mask specifying the platform specific bits.
+ @see PaStreamFlags
+*}
+const   paPlatformSpecificFlags = TPaStreamFlags($FFFF0000);
+
+{**
+ Timing information for the buffers passed to the stream callback.
+*}
+type
+  PPaStreamCallbackTimeInfo = ^TPaStreamCallbackTimeInfo;
+  TPaStreamCallbackTimeInfo = record
+      inputBufferAdcTime: TPaTime;
+      currentTime: TPaTime;
+      outputBufferDacTime: TPaTime;
+  end;
+
+
+{**
+ Flag bit constants for the statusFlags to PaStreamCallback.
+
+ @see paInputUnderflow, paInputOverflow, paOutputUnderflow, paOutputOverflow,
+ paPrimingOutput
+*}
+type TPaStreamCallbackFlags = culong;
+
+{** 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
+*}
+const paInputUnderflow   = TPaStreamCallbackFlags($00000001);
+
+{** 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
+*}
+const paInputOverflow    = TPaStreamCallbackFlags($00000002);
+
+{** Indicates that output data (or a gap) was inserted, possibly because the
+ stream callback is using too much CPU time.
+ @see PaStreamCallbackFlags
+*}
+const paOutputUnderflow  = TPaStreamCallbackFlags($00000004);
+
+{** Indicates that output data will be discarded because no room is available.
+ @see PaStreamCallbackFlags
+*}
+const paOutputOverflow   = TPaStreamCallbackFlags($00000008);
+
+{** Some of all of the output data will be used to prime the stream, input
+ data may be zero.
+ @see PaStreamCallbackFlags
+*}
+const paPrimingOutput    = TPaStreamCallbackFlags($00000010);
+
+{**
+ Allowable return values for the PaStreamCallback.
+ @see PaStreamCallback
+*}
+type TPaStreamCallbackResult = {enum}cint; const
+{enum_begin PaStreamCallbackResult}
+    paContinue=0;
+    paComplete=1;
+    paAbort=2;
+{enum_end 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.
+     
+ @param input and @param output are arrays of interleaved samples,
+ 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 The time in seconds when the first sample of the input
+ buffer was received at the audio input, the time in seconds when the first
+ sample of the output buffer will begin being played at the audio output, and
+ the time in seconds when the stream callback was called.
+ See also 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 utilise 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 permissable to call
+ PortAudio API functions from within the stream callback.
+*}
+type
+  PPaStreamCallback = ^TPaStreamCallback;
+  TPaStreamCallback = function(
+      input: Pointer; output: Pointer;
+      frameCount: culong;
+      timeInfo: PPaStreamCallbackTimeInfo;
+      statusFlags: TPaStreamCallbackFlags;
+      userData: Pointer ): cint; cdecl;
+
+
+{** 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 recieve 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 behaviour 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
+*}
+function Pa_OpenStream( var stream: PPaStream;
+                       inputParameters: PPaStreamParameters;
+                       outputParameters: PPaStreamParameters;
+                       sampleRate: cdouble;
+                       framesPerBuffer: culong;
+                       streamFlags: TPaStreamFlags;
+                       streamCallback: PPaStreamCallback;
+                       userData: Pointer ): TPaError; cdecl; external LibName;
+
+
+{** 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 dvice.
+ 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
+*}
+function Pa_OpenDefaultStream( var stream: PPaStream;
+                              numInputChannels: cint;
+                              numOutputChannels: cint;
+                              sampleFormat: TPaSampleFormat;
+                              sampleRate: cdouble;
+                              framesPerBuffer: culong;
+                              streamCallback: PPaStreamCallback;
+                              userData: Pointer ): TPaError; cdecl; external LibName;
+
+
+{** Closes an audio stream. If the audio stream is active it
+ discards any pending buffers as if Pa_AbortStream() had been called.
+*}
+function Pa_CloseStream( stream: PPaStream ): TPaError; cdecl; external LibName;
+
+
+{** 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
+*}
+type
+  PPaStreamFinishedCallback = ^TPaStreamFinishedCallback;
+  TPaStreamFinishedCallback = procedure( userData: Pointer ); cdecl;
+
+
+{** 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
+*}
+function Pa_SetStreamFinishedCallback( stream: PPaStream;
+                streamFinishedCallback: PPaStreamFinishedCallback ): TPaError; cdecl; external LibName;
+
+
+{** Commences audio processing.
+*}
+function Pa_StartStream( stream: PPaStream ): TPaError; cdecl; external LibName;
+
+
+{** Terminates audio processing. It waits until all pending
+ audio buffers have been played before it returns.
+*}
+function Pa_StopStream( stream: PPaStream ): TPaError; cdecl; external LibName;
+
+
+{** Terminates audio processing immediately without waiting for pending
+ buffers to complete.
+*}
+function Pa_AbortStream( stream: PPaStream ): TPaError; cdecl; external LibName;
+
+
+{** 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
+*}
+function Pa_IsStreamStopped( stream: PPaStream ): TPaError; cdecl; external LibName;
+
+
+{** 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
+*}
+function Pa_IsStreamActive( stream: PPaStream ): TPaError; cdecl; external LibName;
+
+
+
+{** A structure containing unchanging information about an open stream.
+ @see Pa_GetStreamInfo
+*}
+type
+  PPaStreamInfo = ^TPaStreamInfo;
+  TPaStreamInfo = record
+      {** this is struct version 1 *}
+      structVersion: cint;
+
+      {** 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
+      *}
+      inputLatency: TPaTime;
+
+      {** 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
+      *}
+      outputLatency: TPaTime;
+
+      {** 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().
+      *}
+      sampleRate: cdouble;
+  end;
+
+
+{** 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 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
+*}
+function Pa_GetStreamInfo( stream: PPaStream ): PPaStreamInfo; cdecl; external LibName;
+
+
+{** Determine the current time for the stream according to the same clock used
+ to generate buffer timestamps. This time may be used for syncronising 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
+*}
+function Pa_GetStreamTime( stream: PPaStream ): TPaTime; cdecl; external LibName;
+
+
+{** 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 occurrs.
+*}
+function Pa_GetStreamCpuLoad( stream: PPaStream ): cdouble; cdecl; external LibName;
+
+
+{** 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,
+ buffer is a pointer to the first element of an array of non-interleaved
+ buffer pointers, one 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.
+*}
+function Pa_ReadStream( stream: PPaStream;
+                       buffer: Pointer;
+                       frames: culong ): TPaError; cdecl; external LibName;
+
+
+{** 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,
+ buffer is a pointer to the first element of an array of non-interleaved
+ buffer pointers, one 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.
+*}
+function Pa_WriteStream( stream: PPaStream;
+                        buffer: Pointer;
+                        frames: culong ): TPaError; cdecl; external LibName;
+
+
+{** 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.
+*}
+function Pa_GetStreamReadAvailable( stream: PPaStream ): cslong; cdecl; external LibName;
+
+
+{** 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.
+*}
+function Pa_GetStreamWriteAvailable( stream: PPaStream ): cslong; cdecl; external LibName;
+
+
+{** Retrieve the host type handling an open stream.
+
+ @return Returns a non-negative value representing the host API type
+ handling an open stream or, a PaErrorCode (which are always negative)
+ if PortAudio is not initialized or an error is encountered.
+*}
+function Pa_GetStreamHostApiType( stream: PPaStream ): TPaHostApiTypeId; cdecl; external LibName;
+
+
+{* 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.
+*}
+function Pa_GetSampleSize( format: TPaSampleFormat ): TPaError; cdecl; external LibName;
+
+
+{** 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.
+*}
+procedure Pa_Sleep( msec: clong ); cdecl; external LibName;
+
+implementation
+
+end.

@@ -10,6 +10,8 @@ unit sherpa_onnx;
 (* {$LongStrings ON} *)
 
 interface
+uses
+  ctypes;
 
 type
   TSherpaOnnxWave = record
@@ -260,7 +262,8 @@ type
   public
     constructor Create(Capacity: Integer);
     destructor Destroy; override;
-    procedure Push(Samples: array of Single);
+    procedure Push(Samples: array of Single); overload;
+    procedure Push(Samples: pcfloat; N: Integer); overload;
     function Get(StartIndex: Integer; N: Integer): TSherpaOnnxSamplesArray;
     procedure Pop(N: Integer);
     procedure Reset;
@@ -305,7 +308,6 @@ type
 implementation
 
 uses
-  ctypes,
   fpjson,
     { See
       - https://wiki.freepascal.org/fcl-json
@@ -1323,6 +1325,11 @@ begin
   SherpaOnnxCircularBufferPush(Self.Handle, pcfloat(Samples), Length(Samples));
 end;
 
+procedure TSherpaOnnxCircularBuffer.Push(Samples: pcfloat; N: Integer);
+begin
+  SherpaOnnxCircularBufferPush(Self.Handle, Samples, N);
+end;
+
 function TSherpaOnnxCircularBuffer.Get(StartIndex: Integer; N: Integer): TSherpaOnnxSamplesArray;
 var
   P: pcfloat;