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

pascal-api-examples/portaudio-test/test-play.pas

@@ -0,0 +1,160 @@
+{ 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.
+