Add C API for Kokoro TTS models (#1717)

cxx-api-examples/CMakeLists.txt

@@ -21,4 +21,7 @@ if(SHERPA_ONNX_ENABLE_TTS)
 
   add_executable(matcha-tts-en-cxx-api ./matcha-tts-en-cxx-api.cc)
   target_link_libraries(matcha-tts-en-cxx-api sherpa-onnx-cxx-api)
+
+  add_executable(kokoro-tts-en-cxx-api ./kokoro-tts-en-cxx-api.cc)
+  target_link_libraries(kokoro-tts-en-cxx-api sherpa-onnx-cxx-api)
 endif()

cxx-api-examples/kokoro-tts-en-cxx-api.cc

@@ -0,0 +1,73 @@
+// cxx-api-examples/kokoro-tts-en-cxx-api.c
+//
+// Copyright (c)  2025  Xiaomi Corporation
+
+// This file shows how to use sherpa-onnx CXX API
+// for Chinese TTS with Kokoro.
+//
+// clang-format off
+/*
+Usage
+
+wget https://github.com/k2-fsa/sherpa-onnx/releases/download/tts-models/kokoro-en-v0_19.tar.bz2
+tar xf kokoro-en-v0_19.tar.bz2
+rm kokoro-en-v0_19.tar.bz2
+
+./kokoro-tts-en-cxx-api
+
+ */
+// clang-format on
+
+#include <string>
+
+#include "sherpa-onnx/c-api/cxx-api.h"
+
+static int32_t ProgressCallback(const float *samples, int32_t num_samples,
+                                float progress, void *arg) {
+  fprintf(stderr, "Progress: %.3f%%\n", progress * 100);
+  // return 1 to continue generating
+  // return 0 to stop generating
+  return 1;
+}
+
+int32_t main(int32_t argc, char *argv[]) {
+  using namespace sherpa_onnx::cxx;  // NOLINT
+  OfflineTtsConfig config;
+
+  config.model.kokoro.model = "./kokoro-en-v0_19/model.onnx";
+  config.model.kokoro.voices = "./kokoro-en-v0_19/voices.bin";
+  config.model.kokoro.tokens = "./kokoro-en-v0_19/tokens.txt";
+  config.model.kokoro.data_dir = "./kokoro-en-v0_19/espeak-ng-data";
+
+  config.model.num_threads = 2;
+
+  // If you don't want to see debug messages, please set it to 0
+  config.model.debug = 1;
+
+  std::string filename = "./generated-kokoro-en-cxx.wav";
+  std::string 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. "
+      "Friends fell out often because life was changing so fast. The easiest "
+      "thing in the world was to lose touch with someone.";
+
+  auto tts = OfflineTts::Create(config);
+  int32_t sid = 0;
+  float speed = 1.0;  // larger -> faster in speech speed
+
+#if 0
+  // If you don't want to use a callback, then please enable this branch
+  GeneratedAudio audio = tts.Generate(text, sid, speed);
+#else
+  GeneratedAudio audio = tts.Generate(text, sid, speed, ProgressCallback);
+#endif
+
+  WriteWave(filename, {audio.samples, audio.sample_rate});
+
+  fprintf(stderr, "Input text is: %s\n", text.c_str());
+  fprintf(stderr, "Speaker ID is is: %d\n", sid);
+  fprintf(stderr, "Saved to: %s\n", filename.c_str());
+
+  return 0;
+}