diff --git a/.github/workflows/pascal.yaml b/.github/workflows/pascal.yaml
index e780c39f7..2ed213184 100644
--- a/.github/workflows/pascal.yaml
+++ b/.github/workflows/pascal.yaml
@@ -119,13 +119,29 @@ jobs:
             cp -v install/lib/*.dll ../pascal-api-examples/vad
             cp -v install/lib/*.dll ../pascal-api-examples/vad-with-non-streaming-asr
 
-            cp -v ../sherpa-onnx/pascal-api/sherpa_onnx.pas ../pascal-api-examples/read-wav
-            cp -v ../sherpa-onnx/pascal-api/sherpa_onnx.pas ../pascal-api-examples/streaming-asr
-            cp -v ../sherpa-onnx/pascal-api/sherpa_onnx.pas ../pascal-api-examples/non-streaming-asr
-            cp -v ../sherpa-onnx/pascal-api/sherpa_onnx.pas ../pascal-api-examples/vad
-            cp -v ../sherpa-onnx/pascal-api/sherpa_onnx.pas ../pascal-api-examples/vad-with-non-streaming-asr
+            cp -v ../sherpa-onnx/pascal-api/*.pas ../pascal-api-examples/read-wav
+            cp -v ../sherpa-onnx/pascal-api/*.pas ../pascal-api-examples/streaming-asr
+            cp -v ../sherpa-onnx/pascal-api/*.pas ../pascal-api-examples/non-streaming-asr
+            cp -v ../sherpa-onnx/pascal-api/*.pas ../pascal-api-examples/vad
+            cp -v ../sherpa-onnx/pascal-api/*.pas ../pascal-api-examples/vad-with-non-streaming-asr
+            cp -v ../sherpa-onnx/pascal-api/*.pas ../pascal-api-examples/tts
           fi
 
+      - name:  Run Pascal test (TTS)
+        shell: bash
+        run: |
+          export PATH=/c/lazarus/fpc/3.2.2/bin/x86_64-win64:$PATH
+
+          cd ./pascal-api-examples
+          pushd tts
+
+          ./run-piper.sh
+          rm -rf vits-piper-*
+          ls -lh
+          echo "---"
+
+          popd
+
       - name:  Run Pascal test (VAD + non-streaming ASR)
         shell: bash
         run: |
diff --git a/pascal-api-examples/.gitignore b/pascal-api-examples/.gitignore
new file mode 100644
index 000000000..30740b9de
--- /dev/null
+++ b/pascal-api-examples/.gitignore
@@ -0,0 +1 @@
+link*.res
diff --git a/pascal-api-examples/README.md b/pascal-api-examples/README.md
index ffbf8e9ef..5475d825b 100644
--- a/pascal-api-examples/README.md
+++ b/pascal-api-examples/README.md
@@ -13,3 +13,5 @@ https://k2-fsa.github.io/sherpa/onnx/pascal-api/index.html
 |[non-streaming-asr](./non-streaming-asr)| It shows how to use non-streaming models for speech recognition.|
 |[vad](./vad)| It shows how to use the voice activity detection API.|
 |[vad-with-non-streaming-asr](./vad-with-non-streaming-asr)| It shows how to use the voice activity detection API with non-streaming models for speech recognition.|
+|[portaudio-test](./portaudio-test)| It shows how to use PortAudio for recording and playing.|
+|[tts](./tts)| It shows how to use the text-to-speech API.|
diff --git a/pascal-api-examples/tts/.gitignore b/pascal-api-examples/tts/.gitignore
new file mode 100644
index 000000000..b7076ab5c
--- /dev/null
+++ b/pascal-api-examples/tts/.gitignore
@@ -0,0 +1,4 @@
+!run-*.sh
+piper
+piper-playback
+link*.res
diff --git a/pascal-api-examples/tts/README.md b/pascal-api-examples/tts/README.md
new file mode 100644
index 000000000..4bb050290
--- /dev/null
+++ b/pascal-api-examples/tts/README.md
@@ -0,0 +1,9 @@
+# Introduction
+
+This directory contains examples for how to use the TTS (text to speech) APIs.
+
+|Directory| Description|
+|---------|------------|
+|[run-piper.sh](./run-piper.sh)|It shows how to use models from [piper](https://github.com/rhasspy/piper) for text to speech.|
+|[run-piper-playback.sh](./run-piper-playback.sh)|It shows how to use models from [piper](https://github.com/rhasspy/piper) for text to speech. It plays the generated audio as it is still generating. |
+
diff --git a/pascal-api-examples/tts/piper-playback.pas b/pascal-api-examples/tts/piper-playback.pas
new file mode 100644
index 000000000..b9cd10b71
--- /dev/null
+++ b/pascal-api-examples/tts/piper-playback.pas
@@ -0,0 +1,238 @@
+{ Copyright (c)  2024  Xiaomi Corporation }
+program piper;
+{
+This file shows how to use the text to speech API of sherpa-onnx
+with Piper models.
+
+It generates speech from text and saves it to a wave file.
+
+Note that it plays the audio back as it is still generating.
+}
+
+{$mode objfpc}
+
+uses
+  {$ifdef unix}
+  cthreads,
+  {$endif}
+  SysUtils,
+  dos,
+  ctypes,
+  portaudio,
+  sherpa_onnx;
+
+var
+  CriticalSection: TRTLCriticalSection;
+
+  Tts: TSherpaOnnxOfflineTts;
+  Audio: TSherpaOnnxGeneratedAudio;
+  Resampler: TSherpaOnnxLinearResampler;
+
+  Text: AnsiString;
+  Speed: Single = 1.0;  {Use a larger value to speak faster}
+  SpeakerId: Integer = 0;
+  Buffer: TSherpaOnnxCircularBuffer;
+  FinishedGeneration: Boolean = False;
+  FinishedPlaying: Boolean = False;
+
+  Version: String;
+  EnvStr: String;
+  Status: Integer;
+  NumDevices: Integer;
+  DeviceIndex: Integer;
+  DeviceInfo: PPaDeviceInfo;
+
+  { If you get EDivByZero: Division by zero error, please change the sample rate
+    to the one supported by your microphone.
+  }
+  DeviceSampleRate: Integer = 48000;
+  I: Integer;
+  Param: TPaStreamParameters;
+  Stream: PPaStream;
+  Wave: TSherpaOnnxWave;
+
+function GenerateCallback(
+      Samples: pcfloat; N: cint32;
+      Arg: Pointer): cint; cdecl;
+begin
+  EnterCriticalSection(CriticalSection);
+  try
+    if Resampler <> nil then
+      Buffer.Push(Resampler.Resample(Samples, N, False))
+    else
+      Buffer.Push(Samples, N);
+  finally
+    LeaveCriticalSection(CriticalSection);
+  end;
+
+  { 1 means to continue generating; 0 means to stop generating. }
+  Result := 1;
+end;
+
+function PlayCallback(
+      input: Pointer; output: Pointer;
+      frameCount: culong;
+      timeInfo: PPaStreamCallbackTimeInfo;
+      statusFlags: TPaStreamCallbackFlags;
+      userData: Pointer ): cint; cdecl;
+var
+  Samples: TSherpaOnnxSamplesArray;
+  I: Integer;
+begin
+  EnterCriticalSection(CriticalSection);
+  try
+    if Buffer.Size >= frameCount then
+      begin
+        Samples := Buffer.Get(Buffer.Head, FrameCount);
+        Buffer.Pop(FrameCount);
+      end
+    else if Buffer.Size > 0 then
+      begin
+        Samples := Buffer.Get(Buffer.Head, Buffer.Size);
+        Buffer.Pop(Buffer.Size);
+        SetLength(Samples, frameCount);
+      end
+    else
+      SetLength(Samples, frameCount);
+
+    for I := 0 to frameCount - 1 do
+      pcfloat(output)[I] := Samples[I];
+
+    if (Buffer.Size > 0) or (not FinishedGeneration) then
+      Result := paContinue
+    else
+      begin
+        Result := paComplete;
+        FinishedPlaying := True;
+      end;
+  finally
+    LeaveCriticalSection(CriticalSection);
+  end;
+end;
+
+function GetOfflineTts: TSherpaOnnxOfflineTts;
+var
+  Config: TSherpaOnnxOfflineTtsConfig;
+begin
+  Config.Model.Vits.Model := './vits-piper-en_US-libritts_r-medium/en_US-libritts_r-medium.onnx';
+  Config.Model.Vits.Tokens := './vits-piper-en_US-libritts_r-medium/tokens.txt';
+  Config.Model.Vits.DataDir := './vits-piper-en_US-libritts_r-medium/espeak-ng-data';
+  Config.Model.NumThreads := 1;
+  Config.Model.Debug := False;
+  Config.MaxNumSentences := 1;
+
+  Result := TSherpaOnnxOfflineTts.Create(Config);
+end;
+
+begin
+  Tts := GetOfflineTts;
+  if Tts.GetSampleRate <> DeviceSampleRate then
+    Resampler := TSherpaOnnxLinearResampler.Create(Tts.GetSampleRate, DeviceSampleRate);
+
+  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);
+
+  Initialize(Param);
+  Param.Device := DeviceIndex;
+  Param.ChannelCount := 1;
+  Param.SampleFormat := paFloat32;
+  param.SuggestedLatency := Pa_GetDeviceInfo(DeviceIndex)^.DefaultHighOutputLatency;
+  param.HostApiSpecificStreamInfo := nil;
+
+  Buffer := TSherpaOnnxCircularBuffer.Create(30 * DeviceSampleRate);
+
+
+  { Note(fangjun): PortAudio invokes PlayCallback in a separate thread. }
+  Status := Pa_OpenStream(stream, nil, @Param, DeviceSampleRate, paFramesPerBufferUnspecified, paNoFlag,
+    PPaStreamCallback(@PlayCallback), nil);
+
+  if Status <> paNoError then
+    begin
+      WriteLn('Failed to open stream, ', Pa_GetErrorText(Status));
+      Pa_Terminate;
+      Exit;
+    end;
+
+  InitCriticalSection(CriticalSection);
+
+  Status := Pa_StartStream(stream);
+  if Status <> paNoError then
+    begin
+      WriteLn('Failed to start stream, ', Pa_GetErrorText(Status));
+      Pa_Terminate;
+      Exit;
+    end;
+
+  WriteLn('There are ', Tts.GetNumSpeakers, ' speakers');
+
+  Text := 'Today as always, men fall into two groups: slaves and free men. Whoever does not have two-thirds of his day for himself, is a slave, whatever he may be: a statesman, a businessman, an official, or a scholar.';
+
+  Audio :=  Tts.Generate(Text, SpeakerId, Speed,
+    PSherpaOnnxGeneratedAudioCallbackWithArg(@GenerateCallback), nil);
+  FinishedGeneration := True;
+  SherpaOnnxWriteWave('./libritts_r-generated.wav', Audio.Samples, Audio.SampleRate);
+  WriteLn('Saved to ./libritts_r-generated.wav');
+
+  while not FinishedPlaying do
+    Pa_Sleep(100);  {sleep for 0.1 second }
+    {TODO(fangjun): Use an event to indicate the play is finished}
+
+  DoneCriticalSection(CriticalSection);
+
+  FreeAndNil(Tts);
+  FreeAndNil(Resampler);
+
+  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.
+
diff --git a/pascal-api-examples/tts/piper.pas b/pascal-api-examples/tts/piper.pas
new file mode 100644
index 000000000..7c3fb4e66
--- /dev/null
+++ b/pascal-api-examples/tts/piper.pas
@@ -0,0 +1,54 @@
+{ Copyright (c)  2024  Xiaomi Corporation }
+program piper;
+{
+This file shows how to use the text to speech API of sherpa-onnx
+with Piper models.
+
+It generates speech from text and saves it to a wave file.
+
+If you want to play it while it is generating, please see
+./piper-playback.pas
+}
+
+{$mode objfpc}
+
+uses
+  SysUtils,
+  sherpa_onnx;
+
+function GetOfflineTts: TSherpaOnnxOfflineTts;
+var
+  Config: TSherpaOnnxOfflineTtsConfig;
+begin
+  Config.Model.Vits.Model := './vits-piper-en_US-libritts_r-medium/en_US-libritts_r-medium.onnx';
+  Config.Model.Vits.Tokens := './vits-piper-en_US-libritts_r-medium/tokens.txt';
+  Config.Model.Vits.DataDir := './vits-piper-en_US-libritts_r-medium/espeak-ng-data';
+  Config.Model.NumThreads := 1;
+  Config.Model.Debug := False;
+  Config.MaxNumSentences := 1;
+
+  Result := TSherpaOnnxOfflineTts.Create(Config);
+end;
+
+var
+  Tts: TSherpaOnnxOfflineTts;
+  Audio: TSherpaOnnxGeneratedAudio;
+
+  Text: AnsiString;
+  Speed: Single = 1.0;  {Use a larger value to speak faster}
+  SpeakerId: Integer = 0;
+
+begin
+  Tts := GetOfflineTts;
+
+  WriteLn('There are ', Tts.GetNumSpeakers, ' speakers');
+
+  Text := 'Today as always, men fall into two groups: slaves and free men. Whoever does not have two-thirds of his day for himself, is a slave, whatever he may be: a statesman, a businessman, an official, or a scholar.';
+
+  Audio :=  Tts.Generate(Text, SpeakerId, Speed);
+  SherpaOnnxWriteWave('./libritts_r-generated.wav', Audio.Samples, Audio.SampleRate);
+  WriteLn('Saved to ./libritts_r-generated.wav');
+
+  FreeAndNil(Tts);
+end.
+
diff --git a/pascal-api-examples/tts/run-piper-playback.sh b/pascal-api-examples/tts/run-piper-playback.sh
new file mode 100755
index 000000000..7076dee05
--- /dev/null
+++ b/pascal-api-examples/tts/run-piper-playback.sh
@@ -0,0 +1,45 @@
+#!/usr/bin/env bash
+
+set -ex
+
+SCRIPT_DIR=$( cd -- "$( dirname -- "${BASH_SOURCE[0]}" )" &> /dev/null && pwd )
+SHERPA_ONNX_DIR=$(cd $SCRIPT_DIR/../.. && pwd)
+
+echo "SHERPA_ONNX_DIR: $SHERPA_ONNX_DIR"
+
+if [[ ! -f ../../build/install/lib/libsherpa-onnx-c-api.dylib  && ! -f ../../build/install/lib/libsherpa-onnx-c-api.so && ! -f ../../build/install/lib/sherpa-onnx-c-api.dll ]]; then
+  mkdir -p ../../build
+  pushd ../../build
+  cmake \
+    -DCMAKE_INSTALL_PREFIX=./install \
+    -DSHERPA_ONNX_ENABLE_PYTHON=OFF \
+    -DSHERPA_ONNX_ENABLE_TESTS=OFF \
+    -DSHERPA_ONNX_ENABLE_CHECK=OFF \
+    -DBUILD_SHARED_LIBS=ON \
+    -DSHERPA_ONNX_ENABLE_PORTAUDIO=OFF \
+    ..
+
+  cmake --build . --target install --config Release
+  popd
+fi
+
+if [[ ! -f ./vits-piper-en_US-libritts_r-medium/tokens.txt ]]; then
+  curl -SL -O https://github.com/k2-fsa/sherpa-onnx/releases/download/tts-models/vits-piper-en_US-libritts_r-medium.tar.bz2
+  tar xf vits-piper-en_US-libritts_r-medium.tar.bz2
+  rm vits-piper-en_US-libritts_r-medium.tar.bz2
+fi
+
+fpc \
+  -dSHERPA_ONNX_USE_SHARED_LIBS \
+  -Fu$SHERPA_ONNX_DIR/sherpa-onnx/pascal-api \
+  -Fl$SHERPA_ONNX_DIR/build/install/lib \
+  -Fl/usr/local/Cellar/portaudio/19.7.0/lib \
+  ./piper-playback.pas
+
+# Please see ../portaudio-test/README.md
+# for how to install portaudio on macOS
+
+export LD_LIBRARY_PATH=$SHERPA_ONNX_DIR/build/install/lib:$LD_LIBRARY_PATH
+export DYLD_LIBRARY_PATH=$SHERPA_ONNX_DIR/build/install/lib:$DYLD_LIBRARY_PATH
+
+./piper-playback
diff --git a/pascal-api-examples/tts/run-piper.sh b/pascal-api-examples/tts/run-piper.sh
new file mode 100755
index 000000000..7abed25ee
--- /dev/null
+++ b/pascal-api-examples/tts/run-piper.sh
@@ -0,0 +1,41 @@
+#!/usr/bin/env bash
+
+set -ex
+
+SCRIPT_DIR=$( cd -- "$( dirname -- "${BASH_SOURCE[0]}" )" &> /dev/null && pwd )
+SHERPA_ONNX_DIR=$(cd $SCRIPT_DIR/../.. && pwd)
+
+echo "SHERPA_ONNX_DIR: $SHERPA_ONNX_DIR"
+
+if [[ ! -f ../../build/install/lib/libsherpa-onnx-c-api.dylib  && ! -f ../../build/install/lib/libsherpa-onnx-c-api.so && ! -f ../../build/install/lib/sherpa-onnx-c-api.dll ]]; then
+  mkdir -p ../../build
+  pushd ../../build
+  cmake \
+    -DCMAKE_INSTALL_PREFIX=./install \
+    -DSHERPA_ONNX_ENABLE_PYTHON=OFF \
+    -DSHERPA_ONNX_ENABLE_TESTS=OFF \
+    -DSHERPA_ONNX_ENABLE_CHECK=OFF \
+    -DBUILD_SHARED_LIBS=ON \
+    -DSHERPA_ONNX_ENABLE_PORTAUDIO=OFF \
+    ..
+
+  cmake --build . --target install --config Release
+  popd
+fi
+
+if [[ ! -f ./vits-piper-en_US-libritts_r-medium/tokens.txt ]]; then
+  curl -SL -O https://github.com/k2-fsa/sherpa-onnx/releases/download/tts-models/vits-piper-en_US-libritts_r-medium.tar.bz2
+  tar xf vits-piper-en_US-libritts_r-medium.tar.bz2
+  rm vits-piper-en_US-libritts_r-medium.tar.bz2
+fi
+
+fpc \
+  -dSHERPA_ONNX_USE_SHARED_LIBS \
+  -Fu$SHERPA_ONNX_DIR/sherpa-onnx/pascal-api \
+  -Fl$SHERPA_ONNX_DIR/build/install/lib \
+  ./piper.pas
+
+export LD_LIBRARY_PATH=$SHERPA_ONNX_DIR/build/install/lib:$LD_LIBRARY_PATH
+export DYLD_LIBRARY_PATH=$SHERPA_ONNX_DIR/build/install/lib:$DYLD_LIBRARY_PATH
+
+./piper
diff --git a/scripts/apk/generate-tts-apk-script.py b/scripts/apk/generate-tts-apk-script.py
index 48745c312..291c4738a 100755
--- a/scripts/apk/generate-tts-apk-script.py
+++ b/scripts/apk/generate-tts-apk-script.py
@@ -190,9 +190,9 @@ def get_piper_models() -> List[TtsModel]:
         TtsModel(model_dir="vits-piper-nl_BE-nathalie-x_low"),
         TtsModel(model_dir="vits-piper-nl_BE-rdh-medium"),
         TtsModel(model_dir="vits-piper-nl_BE-rdh-x_low"),
-        TtsModel(model_dir="vits-piper-nl_NL-mls-medium"),
-        TtsModel(model_dir="vits-piper-nl_NL-mls_5809-low"),
-        TtsModel(model_dir="vits-piper-nl_NL-mls_7432-low"),
+        #  TtsModel(model_dir="vits-piper-nl_NL-mls-medium"),
+        #  TtsModel(model_dir="vits-piper-nl_NL-mls_5809-low"),
+        #  TtsModel(model_dir="vits-piper-nl_NL-mls_7432-low"),
         TtsModel(model_dir="vits-piper-no_NO-talesyntese-medium"),
         TtsModel(model_dir="vits-piper-pl_PL-darkman-medium"),
         TtsModel(model_dir="vits-piper-pl_PL-gosia-medium"),
diff --git a/scripts/flutter/generate-tts.py b/scripts/flutter/generate-tts.py
index 380d1f453..3ca5a98fd 100755
--- a/scripts/flutter/generate-tts.py
+++ b/scripts/flutter/generate-tts.py
@@ -180,9 +180,9 @@ def get_piper_models() -> List[TtsModel]:
         TtsModel(model_dir="vits-piper-nl_BE-nathalie-x_low"),
         TtsModel(model_dir="vits-piper-nl_BE-rdh-medium"),
         TtsModel(model_dir="vits-piper-nl_BE-rdh-x_low"),
-        TtsModel(model_dir="vits-piper-nl_NL-mls-medium"),
-        TtsModel(model_dir="vits-piper-nl_NL-mls_5809-low"),
-        TtsModel(model_dir="vits-piper-nl_NL-mls_7432-low"),
+        #  TtsModel(model_dir="vits-piper-nl_NL-mls-medium"),
+        #  TtsModel(model_dir="vits-piper-nl_NL-mls_5809-low"),
+        #  TtsModel(model_dir="vits-piper-nl_NL-mls_7432-low"),
         TtsModel(model_dir="vits-piper-no_NO-talesyntese-medium"),
         TtsModel(model_dir="vits-piper-pl_PL-darkman-medium"),
         TtsModel(model_dir="vits-piper-pl_PL-gosia-medium"),
diff --git a/sherpa-onnx/c-api/c-api.cc b/sherpa-onnx/c-api/c-api.cc
index 46da81ca5..e01ae0478 100644
--- a/sherpa-onnx/c-api/c-api.cc
+++ b/sherpa-onnx/c-api/c-api.cc
@@ -18,6 +18,7 @@
 #include "sherpa-onnx/csrc/offline-punctuation.h"
 #include "sherpa-onnx/csrc/offline-recognizer.h"
 #include "sherpa-onnx/csrc/online-recognizer.h"
+#include "sherpa-onnx/csrc/resample.h"
 #include "sherpa-onnx/csrc/speaker-embedding-extractor.h"
 #include "sherpa-onnx/csrc/speaker-embedding-manager.h"
 #include "sherpa-onnx/csrc/spoken-language-identification.h"
@@ -1584,3 +1585,56 @@ const char *SherpaOfflinePunctuationAddPunct(
 }
 
 void SherpaOfflinePunctuationFreeText(const char *text) { delete[] text; }
+
+struct SherpaOnnxLinearResampler {
+  std::unique_ptr<sherpa_onnx::LinearResample> impl;
+};
+
+SherpaOnnxLinearResampler *SherpaOnnxCreateLinearResampler(
+    int32_t samp_rate_in_hz, int32_t samp_rate_out_hz, float filter_cutoff_hz,
+    int32_t num_zeros) {
+  SherpaOnnxLinearResampler *p = new SherpaOnnxLinearResampler;
+  p->impl = std::make_unique<sherpa_onnx::LinearResample>(
+      samp_rate_in_hz, samp_rate_out_hz, filter_cutoff_hz, num_zeros);
+
+  return p;
+}
+
+void SherpaOnnxDestroyLinearResampler(SherpaOnnxLinearResampler *p) {
+  delete p;
+}
+
+const SherpaOnnxResampleOut *SherpaOnnxLinearResamplerResample(
+    SherpaOnnxLinearResampler *p, const float *input, int32_t input_dim,
+    int32_t flush) {
+  std::vector<float> o;
+  p->impl->Resample(input, input_dim, flush, &o);
+
+  float *s = new float[o.size()];
+  std::copy(o.begin(), o.end(), s);
+
+  SherpaOnnxResampleOut *ans = new SherpaOnnxResampleOut;
+  ans->samples = s;
+  ans->n = static_cast<int32_t>(o.size());
+
+  return ans;
+}
+
+void SherpaOnnxLinearResamplerResampleFree(const SherpaOnnxResampleOut *p) {
+  delete[] p->samples;
+  delete p;
+}
+
+int32_t SherpaOnnxLinearResamplerResampleGetInputSampleRate(
+    const SherpaOnnxLinearResampler *p) {
+  return p->impl->GetInputSamplingRate();
+}
+
+int32_t SherpaOnnxLinearResamplerResampleGetOutputSampleRate(
+    const SherpaOnnxLinearResampler *p) {
+  return p->impl->GetOutputSamplingRate();
+}
+
+void SherpaOnnxLinearResamplerReset(SherpaOnnxLinearResampler *p) {
+  p->impl->Reset();
+}
diff --git a/sherpa-onnx/c-api/c-api.h b/sherpa-onnx/c-api/c-api.h
index 9ddabba00..97b8d8081 100644
--- a/sherpa-onnx/c-api/c-api.h
+++ b/sherpa-onnx/c-api/c-api.h
@@ -1315,6 +1315,52 @@ SHERPA_ONNX_API const char *SherpaOfflinePunctuationAddPunct(
 
 SHERPA_ONNX_API void SherpaOfflinePunctuationFreeText(const char *text);
 
+// for resampling
+SHERPA_ONNX_API typedef struct SherpaOnnxLinearResampler
+    SherpaOnnxLinearResampler;
+
+/*
+      float min_freq = min(sampling_rate_in_hz, samp_rate_out_hz);
+      float lowpass_cutoff = 0.99 * 0.5 * min_freq;
+      int32_t lowpass_filter_width = 6;
+
+      You can set filter_cutoff_hz to lowpass_cutoff
+      sand set num_zeros to lowpass_filter_width
+*/
+// The user has to invoke SherpaOnnxDestroyLinearResampler()
+// to free the returned pointer to avoid memory leak
+SHERPA_ONNX_API SherpaOnnxLinearResampler *SherpaOnnxCreateLinearResampler(
+    int32_t samp_rate_in_hz, int32_t samp_rate_out_hz, float filter_cutoff_hz,
+    int32_t num_zeros);
+
+SHERPA_ONNX_API void SherpaOnnxDestroyLinearResampler(
+    SherpaOnnxLinearResampler *p);
+
+SHERPA_ONNX_API void SherpaOnnxLinearResamplerReset(
+    SherpaOnnxLinearResampler *p);
+
+typedef struct SherpaOnnxResampleOut {
+  const float *samples;
+  int32_t n;
+} SherpaOnnxResampleOut;
+// The user has to invoke SherpaOnnxLinearResamplerResampleFree()
+// to free the returned pointer to avoid memory leak.
+//
+// If this is the last segment, you can set flush to 1; otherwise, please
+// set flush to 0
+SHERPA_ONNX_API const SherpaOnnxResampleOut *SherpaOnnxLinearResamplerResample(
+    SherpaOnnxLinearResampler *p, const float *input, int32_t input_dim,
+    int32_t flush);
+
+SHERPA_ONNX_API void SherpaOnnxLinearResamplerResampleFree(
+    const SherpaOnnxResampleOut *p);
+
+SHERPA_ONNX_API int32_t SherpaOnnxLinearResamplerResampleGetInputSampleRate(
+    const SherpaOnnxLinearResampler *p);
+
+SHERPA_ONNX_API int32_t SherpaOnnxLinearResamplerResampleGetOutputSampleRate(
+    const SherpaOnnxLinearResampler *p);
+
 #if defined(__GNUC__)
 #pragma GCC diagnostic pop
 #endif
diff --git a/sherpa-onnx/pascal-api/sherpa_onnx.pas b/sherpa-onnx/pascal-api/sherpa_onnx.pas
index 603f3d14d..dc0684ebc 100644
--- a/sherpa-onnx/pascal-api/sherpa_onnx.pas
+++ b/sherpa-onnx/pascal-api/sherpa_onnx.pas
@@ -1,4 +1,9 @@
-{ Copyright (c)  2024  Xiaomi Corporation }
+{ Copyright (c)  2024  Xiaomi Corporation
+
+Please see
+https://github.com/k2-fsa/sherpa-onnx/tree/master/pascal-api-examples
+for how to use APIs in this file.
+}
 
 unit sherpa_onnx;
 
@@ -7,13 +12,105 @@
   {$modeSwitch advancedRecords} { to support records with methods }
 {$ENDIF}
 
-(* {$LongStrings ON} *)
+{$LongStrings ON}
 
 interface
 uses
   ctypes;
 
 type
+  TSherpaOnnxSamplesArray = array of Single;
+
+  TSherpaOnnxLinearResampler = class
+  private
+    Handle: Pointer;
+    InputSampleRate: Integer;
+    OutputSampleRate: Integer;
+  public
+    constructor Create(SampleRateIn: Integer; SampleRateOut: Integer);
+    destructor Destroy; override;
+
+    function Resample(Samples: pcfloat;
+      N: Integer; Flush: Boolean): TSherpaOnnxSamplesArray; overload;
+
+    function Resample(Samples: array of Single;
+      Flush: Boolean): TSherpaOnnxSamplesArray; overload;
+
+    procedure Reset;
+
+    property GetInputSampleRate: Integer Read InputSampleRate;
+    property GetOutputSampleRate: Integer Read OutputSampleRate;
+  end;
+
+  PSherpaOnnxGeneratedAudioCallbackWithArg = ^TSherpaOnnxGeneratedAudioCallbackWithArg;
+
+  TSherpaOnnxGeneratedAudioCallbackWithArg = function(
+      Samples: pcfloat; N: cint32;
+      Arg: Pointer): cint; cdecl;
+
+  TSherpaOnnxOfflineTtsVitsModelConfig = record
+    Model: AnsiString;
+    Lexicon: AnsiString;
+    Tokens: AnsiString;
+    DataDir: AnsiString;
+    NoiseScale: Single;
+    NoiseScaleW: Single;
+    LengthScale: Single;
+    DictDir: AnsiString;
+
+    function ToString: AnsiString;
+    class operator Initialize({$IFDEF FPC}var{$ELSE}out{$ENDIF} Dest: TSherpaOnnxOfflineTtsVitsModelConfig);
+  end;
+
+  TSherpaOnnxOfflineTtsModelConfig = record
+    Vits: TSherpaOnnxOfflineTtsVitsModelConfig;
+    NumThreads: Integer;
+    Debug: Boolean;
+    Provider: AnsiString;
+
+    function ToString: AnsiString;
+    class operator Initialize({$IFDEF FPC}var{$ELSE}out{$ENDIF} Dest: TSherpaOnnxOfflineTtsModelConfig);
+  end;
+
+  TSherpaOnnxOfflineTtsConfig = record
+    Model: TSherpaOnnxOfflineTtsModelConfig;
+    RuleFsts: AnsiString;
+    MaxNumSentences: Integer;
+    RuleFars: AnsiString;
+
+    function ToString: AnsiString;
+    class operator Initialize({$IFDEF FPC}var{$ELSE}out{$ENDIF} Dest: TSherpaOnnxOfflineTtsConfig);
+  end;
+
+  TSherpaOnnxGeneratedAudio = record
+    Samples: array of Single;
+    SampleRate: Integer;
+  end;
+
+  TSherpaOnnxOfflineTts = class
+  private
+   Handle: Pointer;
+   SampleRate: Integer;
+   NumSpeakers: Integer;
+   _Config: TSherpaOnnxOfflineTtsConfig;
+  public
+    constructor Create(Config: TSherpaOnnxOfflineTtsConfig);
+    destructor Destroy; override;
+
+    function Generate(Text: AnsiString; SpeakerId: Integer;
+      Speed: Single): TSherpaOnnxGeneratedAudio; overload;
+
+    function Generate(Text: AnsiString; SpeakerId: Integer;
+      Speed: Single;
+      Callback:PSherpaOnnxGeneratedAudioCallbackWithArg;
+      Arg: Pointer
+      ): TSherpaOnnxGeneratedAudio; overload;
+
+    property GetHandle: Pointer Read Handle;
+    property GetSampleRate: Integer Read SampleRate;
+    property GetNumSpeakers: Integer Read NumSpeakers;
+  end;
+
   TSherpaOnnxWave = record
     Samples: array of Single; { normalized to the range [-1, 1] }
     SampleRate: Integer;
@@ -254,7 +351,6 @@   TSherpaOnnxVadModelConfig = record
     class operator Initialize({$IFDEF FPC}var{$ELSE}out{$ENDIF} Dest: TSherpaOnnxVadModelConfig);
   end;
 
-  TSherpaOnnxSamplesArray = array of Single;
 
   TSherpaOnnxCircularBuffer = class
   private
@@ -508,6 +604,94 @@   SherpaOnnxSpeechSegment = record
 
   PSherpaOnnxSpeechSegment = ^SherpaOnnxSpeechSegment;
 
+  SherpaOnnxOfflineTtsVitsModelConfig = record
+    Model: PAnsiChar;
+    Lexicon: PAnsiChar;
+    Tokens: PAnsiChar;
+    DataDir: PAnsiChar;
+    NoiseScale: cfloat;
+    NoiseScaleW: cfloat;
+    LengthScale: cfloat;
+    DictDir: PAnsiChar;
+  end;
+
+  SherpaOnnxOfflineTtsModelConfig = record
+    Vits: SherpaOnnxOfflineTtsVitsModelConfig;
+    NumThreads: cint32;
+    Debug: cint32;
+    Provider: PAnsiChar;
+  end;
+
+  SherpaOnnxOfflineTtsConfig = record
+    Model: SherpaOnnxOfflineTtsModelConfig;
+    RuleFsts: PAnsiChar;
+    MaxNumSentences: cint32;
+    RuleFars: PAnsiChar;
+  end;
+
+  PSherpaOnnxOfflineTtsConfig = ^SherpaOnnxOfflineTtsConfig;
+
+  SherpaOnnxGeneratedAudio = record
+    Samples: pcfloat;
+    N: cint32;
+    SampleRate: cint32;
+  end;
+
+  PSherpaOnnxGeneratedAudio = ^SherpaOnnxGeneratedAudio;
+
+  SherpaOnnxResampleOut = record
+    Samples: pcfloat;
+    N: cint32;
+  end;
+
+  PSherpaOnnxResampleOut = ^SherpaOnnxResampleOut;
+
+function SherpaOnnxCreateLinearResampler(SampleRateInHz: cint32;
+  SampleRateOutHz: cint32;
+  FilterCutoffHz: cfloat;
+  NumZeros: cint32): Pointer; cdecl;
+  external SherpaOnnxLibName;
+
+procedure SherpaOnnxDestroyLinearResampler(P: Pointer); cdecl;
+  external SherpaOnnxLibName;
+
+function SherpaOnnxLinearResamplerResample(P: Pointer;
+  Samples: pcfloat;
+  N: Integer;
+  Flush: Integer): PSherpaOnnxResampleOut; cdecl;
+  external SherpaOnnxLibName;
+
+procedure SherpaOnnxLinearResamplerResampleFree(P: PSherpaOnnxResampleOut); cdecl;
+  external SherpaOnnxLibName;
+
+procedure SherpaOnnxLinearResamplerReset(P: Pointer); cdecl;
+  external SherpaOnnxLibName;
+
+function SherpaOnnxCreateOfflineTts(Config: PSherpaOnnxOfflineTtsConfig): Pointer; cdecl;
+  external SherpaOnnxLibName;
+
+procedure SherpaOnnxDestroyOfflineTts(Tts: Pointer); cdecl;
+  external SherpaOnnxLibName;
+
+function SherpaOnnxOfflineTtsSampleRate(Tts: Pointer): cint32; cdecl;
+  external SherpaOnnxLibName;
+
+function SherpaOnnxOfflineTtsNumSpeakers(Tts: Pointer): cint32; cdecl;
+  external SherpaOnnxLibName;
+
+function SherpaOnnxOfflineTtsGenerate(Tts: Pointer;
+  Text: PAnsiChar; Sid: cint32; Speed: cfloat): PSherpaOnnxGeneratedAudio; cdecl;
+  external SherpaOnnxLibName;
+
+function SherpaOnnxOfflineTtsGenerateWithCallbackWithArg(Tts: Pointer;
+  Text: PAnsiChar; Sid: cint32; Speed: cfloat;
+  Callback: PSherpaOnnxGeneratedAudioCallbackWithArg;
+  Arg: Pointer): PSherpaOnnxGeneratedAudio; cdecl;
+  external SherpaOnnxLibName;
+
+procedure SherpaOnnxDestroyOfflineTtsGeneratedAudio(Audio: Pointer); cdecl;
+  external SherpaOnnxLibName;
+
 function SherpaOnnxCreateVoiceActivityDetector(Config: PSherpaOnnxVadModelConfig;
   BufferSizeInSeconds: cfloat): Pointer; cdecl;
   external SherpaOnnxLibName;
@@ -793,8 +977,7 @@ constructor TSherpaOnnxOnlineRecognizer.Create(Config: TSherpaOnnxOnlineRecogniz
 var
   C: SherpaOnnxOnlineRecognizerConfig;
 begin
-  Initialize(C);
-
+  C := Default(SherpaOnnxOnlineRecognizerConfig);
   C.FeatConfig.SampleRate := Config.FeatConfig.SampleRate;
   C.FeatConfig.FeatureDim := Config.FeatConfig.FeatureDim;
 
@@ -1051,8 +1234,7 @@ constructor TSherpaOnnxOfflineRecognizer.Create(Config: TSherpaOnnxOfflineRecogn
 var
   C: SherpaOnnxOfflineRecognizerConfig;
 begin
-  Initialize(C);
-
+  C := Default(SherpaOnnxOfflineRecognizerConfig);
   C.FeatConfig.SampleRate := Config.FeatConfig.SampleRate;
   C.FeatConfig.FeatureDim := Config.FeatConfig.FeatureDim;
 
@@ -1369,12 +1551,11 @@ function TSherpaOnnxCircularBuffer.Head: Integer;
 
 constructor TSherpaOnnxVoiceActivityDetector.Create(Config: TSherpaOnnxVadModelConfig; BufferSizeInSeconds: Single);
 var
-  C: SherpaOnnxVadModelConfig;
+  C: SherpaOnnxVadModelConfig ;
 begin
+  C := Default(SherpaOnnxVadModelConfig);
   Self._Config := Config;
 
-  Initialize(C);
-
   C.SileroVad.Model := PAnsiChar(Config.SileroVad.Model);
   C.SileroVad.Threshold := Config.SileroVad.Threshold;
   C.SileroVad.MinSilenceDuration := Config.SileroVad.MinSilenceDuration;
@@ -1460,5 +1641,197 @@ procedure TSherpaOnnxVoiceActivityDetector.Flush;
   SherpaOnnxVoiceActivityDetectorFlush(Self.Handle);
 end;
 
-end.
+function TSherpaOnnxOfflineTtsVitsModelConfig.ToString: AnsiString;
+begin
+  Result := Format('TSherpaOnnxOfflineTtsVitsModelConfig(' +
+    'Model := %s, ' +
+    'Lexicon := %s, ' +
+    'Tokens := %s, ' +
+    'DataDir := %s, ' +
+    'NoiseScale := %.2f, ' +
+    'NoiseScaleW := %.2f, ' +
+    'LengthScale := %.2f, ' +
+    'DictDir := %s' +
+    ')',
+    [Self.Model, Self.Lexicon, Self.Tokens, Self.DataDir, Self.NoiseScale,
+     Self.NoiseScaleW, Self.LengthScale, Self.DictDir
+    ]);
+end;
+
+class operator TSherpaOnnxOfflineTtsVitsModelConfig.Initialize({$IFDEF FPC}var{$ELSE}out{$ENDIF} Dest: TSherpaOnnxOfflineTtsVitsModelConfig);
+begin
+  Dest.NoiseScale := 0.667;
+  Dest.NoiseScaleW := 0.8;
+  Dest.LengthScale := 1.0;
+end;
+
+function TSherpaOnnxOfflineTtsModelConfig.ToString: AnsiString;
+begin
+  Result := Format('TSherpaOnnxOfflineTtsModelConfig(' +
+    'Vits := %s, ' +
+    'NumThreads := %d, ' +
+    'Debug := %s, ' +
+    'Provider := %s' +
+    ')',
+    [Self.Vits.ToString, Self.NumThreads, Self.Debug.ToString, Self.Provider
+    ]);
+end;
+
+class operator TSherpaOnnxOfflineTtsModelConfig.Initialize({$IFDEF FPC}var{$ELSE}out{$ENDIF} Dest: TSherpaOnnxOfflineTtsModelConfig);
+begin
+  Dest.NumThreads := 1;
+  Dest.Debug := False;
+  Dest.Provider := 'cpu';
+end;
+
+function TSherpaOnnxOfflineTtsConfig.ToString: AnsiString;
+begin
+  Result := Format('TSherpaOnnxOfflineTtsConfig(' +
+    'Model := %s, ' +
+    'RuleFsts := %s, ' +
+    'MaxNumSentences := %d, ' +
+    'RuleFars := %s' +
+    ')',
+    [Self.Model.ToString, Self.RuleFsts, Self.MaxNumSentences, Self.RuleFars
+    ]);
+end;
+
+class operator TSherpaOnnxOfflineTtsConfig.Initialize({$IFDEF FPC}var{$ELSE}out{$ENDIF} Dest: TSherpaOnnxOfflineTtsConfig);
+begin
+  Dest.MaxNumSentences := 1;
+end;
+
+constructor TSherpaOnnxOfflineTts.Create(Config: TSherpaOnnxOfflineTtsConfig);
+var
+  C: SherpaOnnxOfflineTtsConfig;
+begin
+  C := Default(SherpaOnnxOfflineTtsConfig);
+  Self._Config := Config;
+
+  C.Model.Vits.Model := PAnsiChar(Config.Model.Vits.Model);
+  C.Model.Vits.Lexicon := PAnsiChar(Config.Model.Vits.Lexicon);
+  C.Model.Vits.Tokens := PAnsiChar(Config.Model.Vits.Tokens);
+  C.Model.Vits.DataDir := PAnsiChar(Config.Model.Vits.DataDir);
+  C.Model.Vits.NoiseScale := Config.Model.Vits.NoiseScale;
+  C.Model.Vits.NoiseScaleW := Config.Model.Vits.NoiseScaleW;
+  C.Model.Vits.LengthScale := Config.Model.Vits.LengthScale;
+  C.Model.Vits.DictDir := PAnsiChar(Config.Model.Vits.DictDir);
+
+  C.Model.NumThreads := Config.Model.NumThreads;
+  C.Model.Provider := PAnsiChar(Config.Model.Provider);
+  C.Model.Debug := Ord(Config.Model.Debug);
+
+  C.RuleFsts := PAnsiChar(Config.RuleFsts);
+  C.MaxNumSentences := Config.MaxNumSentences;
+  C.RuleFars := PAnsiChar(Config.RuleFars);
+
+  Self.Handle := SherpaOnnxCreateOfflineTts(@C);
+
+  Self.SampleRate := SherpaOnnxOfflineTtsSampleRate(Self.Handle);
+  Self.NumSpeakers := SherpaOnnxOfflineTtsNumSpeakers(Self.Handle);
+end;
+
+destructor TSherpaOnnxOfflineTts.Destroy;
+begin
+  SherpaOnnxDestroyOfflineTts(Self.Handle);
+  Self.Handle := nil;
+end;
+
+function TSherpaOnnxOfflineTts.Generate(Text: AnsiString; SpeakerId: Integer;
+  Speed: Single): TSherpaOnnxGeneratedAudio;
+var
+  Audio: PSherpaOnnxGeneratedAudio;
+  I: Integer;
+begin
+  Result := Default(TSherpaOnnxGeneratedAudio);
+
+  Audio := SherpaOnnxOfflineTtsGenerate(Self.Handle, PAnsiChar(Text), SpeakerId, Speed);
+
+  SetLength(Result.Samples, Audio^.N);
+  Result.SampleRate := Audio^.SampleRate;
+
+  for I := Low(Result.Samples) to High(Result.Samples) do
+  begin
+    Result.Samples[I] := Audio^.Samples[I];
+  end;
+
+  SherpaOnnxDestroyOfflineTtsGeneratedAudio(audio);
+end;
+
+function TSherpaOnnxOfflineTts.Generate(Text: AnsiString; SpeakerId: Integer;
+  Speed: Single;
+  Callback:PSherpaOnnxGeneratedAudioCallbackWithArg;
+  Arg: Pointer
+  ): TSherpaOnnxGeneratedAudio;
+var
+  Audio: PSherpaOnnxGeneratedAudio;
+  I: Integer;
+begin
+  Result := Default(TSherpaOnnxGeneratedAudio);
+
+  Audio := SherpaOnnxOfflineTtsGenerateWithCallbackWithArg(Self.Handle, PAnsiChar(Text),
+    SpeakerId, Speed, Callback, Arg);
+
+  SetLength(Result.Samples, Audio^.N);
+  Result.SampleRate := Audio^.SampleRate;
+
+  for I := Low(Result.Samples) to High(Result.Samples) do
+  begin
+    Result.Samples[I] := Audio^.Samples[I];
+  end;
+
+  SherpaOnnxDestroyOfflineTtsGeneratedAudio(audio);
+end;
 
+constructor TSherpaOnnxLinearResampler.Create(SampleRateIn: Integer; SampleRateOut: Integer);
+var
+  MinFreq: Single;
+  LowpassCutoff: Single;
+  LowpassFilterWidth: Integer = 6;
+begin
+  if SampleRateIn > SampleRateOut then
+    MinFreq := SampleRateOut
+  else
+    MinFreq := SampleRateIn;
+
+  LowpassCutoff := 0.99 * 0.5 * MinFreq;
+
+  Self.Handle := SherpaOnnxCreateLinearResampler(SampleRateIn,
+    SampleRateOut, LowpassCutoff, LowpassFilterWidth);
+  Self.InputSampleRate := SampleRateIn;
+  Self.OutputSampleRate := SampleRateOut;
+end;
+
+destructor TSherpaOnnxLinearResampler.Destroy;
+begin
+  SherpaOnnxDestroyLinearResampler(Self.Handle);
+  Self.Handle := nil;
+end;
+
+function TSherpaOnnxLinearResampler.Resample(Samples: pcfloat;
+  N: Integer; Flush: Boolean): TSherpaOnnxSamplesArray;
+var
+  P: PSherpaOnnxResampleOut;
+  I: Integer;
+begin
+  Result := Default(TSherpaOnnxSamplesArray);
+  P := SherpaOnnxLinearResamplerResample(Self.Handle, Samples, N, Ord(Flush));
+  SetLength(Result, P^.N);
+
+  for I := Low(Result) to High(Result) do
+    Result[I] := P^.Samples[I];
+
+  SherpaOnnxLinearResamplerResampleFree(P);
+end;
+
+function TSherpaOnnxLinearResampler.Resample(Samples: array of Single; Flush: Boolean): TSherpaOnnxSamplesArray;
+begin
+  Result := Self.Resample(pcfloat(Samples), Length(Samples), Flush);
+end;
+
+procedure TSherpaOnnxLinearResampler.Reset;
+begin
+  SherpaOnnxLinearResamplerReset(Self.Handle);
+end;
+
+end.