Add Python API for keyword spotting (#576)

* Add alsa & microphone support for keyword spotting

* Add python wrapper

sherpa-onnx/python/csrc/CMakeLists.txt

@@ -5,6 +5,7 @@ pybind11_add_module(_sherpa_onnx
   display.cc
   endpoint.cc
   features.cc
+  keyword-spotter.cc
   offline-ctc-fst-decoder-config.cc
   offline-lm-config.cc
   offline-model-config.cc

sherpa-onnx/python/csrc/keyword-spotter.cc

@@ -0,0 +1,82 @@
+// sherpa-onnx/python/csrc/keyword-spotter.cc
+//
+// Copyright (c)  2024  Xiaomi Corporation
+
+#include "sherpa-onnx/python/csrc/keyword-spotter.h"
+
+#include <string>
+#include <vector>
+
+#include "sherpa-onnx/csrc/keyword-spotter.h"
+
+namespace sherpa_onnx {
+
+static void PybindKeywordResult(py::module *m) {
+  using PyClass = KeywordResult;
+  py::class_<PyClass>(*m, "KeywordResult")
+      .def_property_readonly(
+          "keyword",
+          [](PyClass &self) -> py::str {
+            return py::str(PyUnicode_DecodeUTF8(self.keyword.c_str(),
+                                                self.keyword.size(), "ignore"));
+          })
+      .def_property_readonly(
+          "tokens",
+          [](PyClass &self) -> std::vector<std::string> { return self.tokens; })
+      .def_property_readonly(
+          "timestamps",
+          [](PyClass &self) -> std::vector<float> { return self.timestamps; });
+}
+
+static void PybindKeywordSpotterConfig(py::module *m) {
+  using PyClass = KeywordSpotterConfig;
+  py::class_<PyClass>(*m, "KeywordSpotterConfig")
+      .def(py::init<const FeatureExtractorConfig &, const OnlineModelConfig &,
+                    int32_t, int32_t, float, float, const std::string &>(),
+           py::arg("feat_config"), py::arg("model_config"),
+           py::arg("max_active_paths") = 4, py::arg("num_trailing_blanks") = 1,
+           py::arg("keywords_score") = 1.0,
+           py::arg("keywords_threshold") = 0.25, py::arg("keywords_file") = "")
+      .def_readwrite("feat_config", &PyClass::feat_config)
+      .def_readwrite("model_config", &PyClass::model_config)
+      .def_readwrite("max_active_paths", &PyClass::max_active_paths)
+      .def_readwrite("num_trailing_blanks", &PyClass::num_trailing_blanks)
+      .def_readwrite("keywords_score", &PyClass::keywords_score)
+      .def_readwrite("keywords_threshold", &PyClass::keywords_threshold)
+      .def_readwrite("keywords_file", &PyClass::keywords_file)
+      .def("__str__", &PyClass::ToString);
+}
+
+void PybindKeywordSpotter(py::module *m) {
+  PybindKeywordResult(m);
+  PybindKeywordSpotterConfig(m);
+
+  using PyClass = KeywordSpotter;
+  py::class_<PyClass>(*m, "KeywordSpotter")
+      .def(py::init<const KeywordSpotterConfig &>(), py::arg("config"),
+           py::call_guard<py::gil_scoped_release>())
+      .def(
+          "create_stream",
+          [](const PyClass &self) { return self.CreateStream(); },
+          py::call_guard<py::gil_scoped_release>())
+      .def(
+          "create_stream",
+          [](PyClass &self, const std::string &keywords) {
+            return self.CreateStream(keywords);
+          },
+          py::arg("keywords"), py::call_guard<py::gil_scoped_release>())
+      .def("is_ready", &PyClass::IsReady,
+           py::call_guard<py::gil_scoped_release>())
+      .def("decode_stream", &PyClass::DecodeStream,
+           py::call_guard<py::gil_scoped_release>())
+      .def(
+          "decode_streams",
+          [](PyClass &self, std::vector<OnlineStream *> ss) {
+            self.DecodeStreams(ss.data(), ss.size());
+          },
+          py::call_guard<py::gil_scoped_release>())
+      .def("get_result", &PyClass::GetResult,
+           py::call_guard<py::gil_scoped_release>());
+}
+
+}  // namespace sherpa_onnx

sherpa-onnx/python/csrc/keyword-spotter.h

@@ -0,0 +1,16 @@
+// sherpa-onnx/python/csrc/keyword-spotter.h
+//
+// Copyright (c)  2024  Xiaomi Corporation
+
+#ifndef SHERPA_ONNX_PYTHON_CSRC_KEYWORD_SPOTTER_H_
+#define SHERPA_ONNX_PYTHON_CSRC_KEYWORD_SPOTTER_H_
+
+#include "sherpa-onnx/python/csrc/sherpa-onnx.h"
+
+namespace sherpa_onnx {
+
+void PybindKeywordSpotter(py::module *m);
+
+}
+
+#endif  // SHERPA_ONNX_PYTHON_CSRC_KEYWORD_SPOTTER_H_

sherpa-onnx/python/csrc/sherpa-onnx.cc

@@ -8,6 +8,7 @@
 #include "sherpa-onnx/python/csrc/display.h"
 #include "sherpa-onnx/python/csrc/endpoint.h"
 #include "sherpa-onnx/python/csrc/features.h"
+#include "sherpa-onnx/python/csrc/keyword-spotter.h"
 #include "sherpa-onnx/python/csrc/offline-ctc-fst-decoder-config.h"
 #include "sherpa-onnx/python/csrc/offline-lm-config.h"
 #include "sherpa-onnx/python/csrc/offline-model-config.h"
@@ -35,6 +36,7 @@ PYBIND11_MODULE(_sherpa_onnx, m) {
   PybindOnlineStream(&m);
   PybindEndpoint(&m);
   PybindOnlineRecognizer(&m);
+  PybindKeywordSpotter(&m);
 
   PybindDisplay(&m);