Add a C++ example to show streaming VAD + non-streaming ASR. (#420)

@@ -137,6 +137,7 @@ class BuildExtension(build_ext):
         binaries += ["sherpa-onnx-offline-websocket-server"]
         binaries += ["sherpa-onnx-online-websocket-client"]
         binaries += ["sherpa-onnx-vad-microphone"]
+        binaries += ["sherpa-onnx-vad-microphone-offline-asr"]
         binaries += ["sherpa-onnx-offline-tts"]
 
         if is_windows():

@@ -57,6 +57,7 @@ def get_binaries_to_install():
     binaries += ["sherpa-onnx-offline-websocket-server"]
     binaries += ["sherpa-onnx-online-websocket-client"]
     binaries += ["sherpa-onnx-vad-microphone"]
+    binaries += ["sherpa-onnx-vad-microphone-offline-asr"]
     binaries += ["sherpa-onnx-offline-tts"]
     if is_windows():
         binaries += ["kaldi-native-fbank-core.dll"]

@@ -225,6 +225,11 @@ if(SHERPA_ONNX_ENABLE_PORTAUDIO)
     microphone.cc
   )
 
+  add_executable(sherpa-onnx-vad-microphone-offline-asr
+    sherpa-onnx-vad-microphone-offline-asr.cc
+    microphone.cc
+  )
+
   if(BUILD_SHARED_LIBS)
     set(PA_LIB portaudio)
   else()
@@ -235,6 +240,7 @@ if(SHERPA_ONNX_ENABLE_PORTAUDIO)
     sherpa-onnx-microphone
     sherpa-onnx-microphone-offline
     sherpa-onnx-vad-microphone
+    sherpa-onnx-vad-microphone-offline-asr
   )
   foreach(exe IN LISTS exes)
     target_link_libraries(${exe} ${PA_LIB} sherpa-onnx-core)

+// sherpa-onnx/csrc/sherpa-onnx-vad-microphone-offline-asr.cc
+//
+// Copyright (c)  2022-2023  Xiaomi Corporation
+
+#include <signal.h>
+#include <stdio.h>
+#include <stdlib.h>
+
+#include <algorithm>
+#include <mutex>  // NOLINT
+
+#include "portaudio.h"  // NOLINT
+#include "sherpa-onnx/csrc/circular-buffer.h"
+#include "sherpa-onnx/csrc/microphone.h"
+#include "sherpa-onnx/csrc/offline-recognizer.h"
+#include "sherpa-onnx/csrc/voice-activity-detector.h"
+
+bool stop = false;
+std::mutex mutex;
+sherpa_onnx::CircularBuffer buffer(16000 * 60);
+
+static int32_t RecordCallback(const void *input_buffer,
+                              void * /*output_buffer*/,
+                              unsigned long frames_per_buffer,  // NOLINT
+                              const PaStreamCallbackTimeInfo * /*time_info*/,
+                              PaStreamCallbackFlags /*status_flags*/,
+                              void *user_data) {
+  std::lock_guard<std::mutex> lock(mutex);
+  buffer.Push(reinterpret_cast<const float *>(input_buffer), frames_per_buffer);
+
+  return stop ? paComplete : paContinue;
+}
+
+static void Handler(int32_t sig) {
+  stop = true;
+  fprintf(stderr, "\nCaught Ctrl + C. Exiting...\n");
+}
+
+int32_t main(int32_t argc, char *argv[]) {
+  signal(SIGINT, Handler);
+
+  const char *kUsageMessage = R"usage(
+This program shows how to use a streaming VAD with non-streaming ASR in
+sherpa-onnx.
+
+Please download silero_vad.onnx from
+https://github.com/snakers4/silero-vad/blob/master/files/silero_vad.onnx
+
+For instance, use
+wget https://github.com/snakers4/silero-vad/raw/master/files/silero_vad.onnx
+
+Please refer to ./sherpa-onnx-microphone-offline.cc
+to download models for offline ASR.
+
+(1) Transducer from icefall
+
+  ./bin/sherpa-onnx-vad-microphone-offline-asr \
+    --silero-vad-model=/path/to/silero_vad.onnx \
+    --tokens=/path/to/tokens.txt \
+    --encoder=/path/to/encoder.onnx \
+    --decoder=/path/to/decoder.onnx \
+    --joiner=/path/to/joiner.onnx
+
+(2) Paraformer from FunASR
+
+  ./bin/sherpa-onnx-vad-microphone-offline-asr \
+    --silero-vad-model=/path/to/silero_vad.onnx \
+    --tokens=/path/to/tokens.txt \
+    --paraformer=/path/to/model.onnx \
+    --num-threads=1
+
+(3) Whisper models
+
+  ./bin/sherpa-onnx-vad-microphone-offline-asr \
+    --silero-vad-model=/path/to/silero_vad.onnx \
+    --whisper-encoder=./sherpa-onnx-whisper-base.en/base.en-encoder.int8.onnx \
+    --whisper-decoder=./sherpa-onnx-whisper-base.en/base.en-decoder.int8.onnx \
+    --tokens=./sherpa-onnx-whisper-base.en/base.en-tokens.txt \
+    --num-threads=1
+)usage";
+
+  sherpa_onnx::ParseOptions po(kUsageMessage);
+  sherpa_onnx::VadModelConfig vad_config;
+
+  sherpa_onnx::OfflineRecognizerConfig asr_config;
+
+  vad_config.Register(&po);
+  asr_config.Register(&po);
+
+  po.Read(argc, argv);
+  if (po.NumArgs() != 0) {
+    po.PrintUsage();
+    exit(EXIT_FAILURE);
+  }
+
+  fprintf(stderr, "%s\n", vad_config.ToString().c_str());
+  fprintf(stderr, "%s\n", asr_config.ToString().c_str());
+
+  if (!vad_config.Validate()) {
+    fprintf(stderr, "Errors in vad_config!\n");
+    return -1;
+  }
+
+  if (!asr_config.Validate()) {
+    fprintf(stderr, "Errors in asr_config!\n");
+    return -1;
+  }
+
+  fprintf(stderr, "Creating recognizer ...\n");
+  sherpa_onnx::OfflineRecognizer recognizer(asr_config);
+  fprintf(stderr, "Recognizer created!\n");
+
+  sherpa_onnx::Microphone mic;
+
+  PaDeviceIndex num_devices = Pa_GetDeviceCount();
+  fprintf(stderr, "Num devices: %d\n", num_devices);
+
+  PaStreamParameters param;
+
+  param.device = Pa_GetDefaultInputDevice();
+  if (param.device == paNoDevice) {
+    fprintf(stderr, "No default input device found\n");
+    exit(EXIT_FAILURE);
+  }
+  fprintf(stderr, "Use default device: %d\n", param.device);
+
+  const PaDeviceInfo *info = Pa_GetDeviceInfo(param.device);
+  fprintf(stderr, "  Name: %s\n", info->name);
+  fprintf(stderr, "  Max input channels: %d\n", info->maxInputChannels);
+
+  param.channelCount = 1;
+  param.sampleFormat = paFloat32;
+
+  param.suggestedLatency = info->defaultLowInputLatency;
+  param.hostApiSpecificStreamInfo = nullptr;
+  float sample_rate = 16000;
+
+  PaStream *stream;
+  PaError err =
+      Pa_OpenStream(&stream, &param, nullptr, /* &outputParameters, */
+                    sample_rate,
+                    0,          // frames per buffer
+                    paClipOff,  // we won't output out of range samples
+                                // so don't bother clipping them
+                    RecordCallback, nullptr);
+  if (err != paNoError) {
+    fprintf(stderr, "portaudio error: %s\n", Pa_GetErrorText(err));
+    exit(EXIT_FAILURE);
+  }
+
+  err = Pa_StartStream(stream);
+  if (err != paNoError) {
+    fprintf(stderr, "portaudio error: %s\n", Pa_GetErrorText(err));
+    exit(EXIT_FAILURE);
+  }
+
+  auto vad = std::make_unique<sherpa_onnx::VoiceActivityDetector>(vad_config);
+
+  fprintf(stderr, "Started. Please speak\n");
+
+  int32_t window_size = vad_config.silero_vad.window_size;
+  int32_t index = 0;
+
+  while (!stop) {
+    {
+      std::lock_guard<std::mutex> lock(mutex);
+
+      while (buffer.Size() >= window_size) {
+        std::vector<float> samples = buffer.Get(buffer.Head(), window_size);
+        buffer.Pop(window_size);
+        vad->AcceptWaveform(samples.data(), samples.size());
+      }
+    }
+
+    while (!vad->Empty()) {
+      auto &segment = vad->Front();
+      auto s = recognizer.CreateStream();
+      s->AcceptWaveform(sample_rate, segment.samples.data(),
+                        segment.samples.size());
+      recognizer.DecodeStream(s.get());
+      const auto &result = s->GetResult();
+      if (!result.text.empty()) {
+        fprintf(stderr, "%2d: %s\n", index, result.text.c_str());
+        ++index;
+      }
+      vad->Pop();
+    }
+
+    Pa_Sleep(100);  // sleep for 100ms
+  }
+
+  err = Pa_CloseStream(stream);
+  if (err != paNoError) {
+    fprintf(stderr, "portaudio error: %s\n", Pa_GetErrorText(err));
+    exit(EXIT_FAILURE);
+  }
+
+  return 0;
+}

@@ -102,7 +102,7 @@ wget https://github.com/snakers4/silero-vad/raw/master/files/silero_vad.onnx
                     0,          // frames per buffer
                     paClipOff,  // we won't output out of range samples
                                 // so don't bother clipping them
-                    RecordCallback, &config.silero_vad.window_size);
+                    RecordCallback, nullptr);
   if (err != paNoError) {
     fprintf(stderr, "portaudio error: %s\n", Pa_GetErrorText(err));
     exit(EXIT_FAILURE);