Add C++ runtime for speech enhancement GTCRN models (#1977)

See also https://github.com/Xiaobin-Rong/gtcrn

sherpa-onnx/csrc/offline-speech-denoiser.h

@@ -0,0 +1,61 @@
+// sherpa-onnx/csrc/offline-speech-denoiser.h
+//
+// Copyright (c)  2025  Xiaomi Corporation
+#ifndef SHERPA_ONNX_CSRC_OFFLINE_SPEECH_DENOISER_H_
+#define SHERPA_ONNX_CSRC_OFFLINE_SPEECH_DENOISER_H_
+
+#include <memory>
+#include <string>
+#include <vector>
+
+#include "sherpa-onnx/csrc/offline-speech-denoiser-model-config.h"
+#include "sherpa-onnx/csrc/parse-options.h"
+
+namespace sherpa_onnx {
+
+struct DenoisedAudio {
+  std::vector<float> samples;
+  int32_t sample_rate;
+};
+
+struct OfflineSpeechDenoiserConfig {
+  OfflineSpeechDenoiserModelConfig model;
+
+  void Register(ParseOptions *po);
+  bool Validate() const;
+
+  std::string ToString() const;
+};
+
+class OfflineSpeechDenoiserImpl;
+
+class OfflineSpeechDenoiser {
+ public:
+  explicit OfflineSpeechDenoiser(const OfflineSpeechDenoiserConfig &config);
+  ~OfflineSpeechDenoiser();
+
+  template <typename Manager>
+  OfflineSpeechDenoiser(Manager *mgr,
+                        const OfflineSpeechDenoiserConfig &config);
+
+  /*
+   * @param samples 1-D array of audio samples. Each sample is in the
+   *                range [-1, 1].
+   * @param n Number of samples
+   * @param sample_rate Sample rate of the input samples
+   *
+   */
+  DenoisedAudio Run(const float *samples, int32_t n, int32_t sample_rate) const;
+
+  /*
+   * Return the sample rate of the denoised audio
+   */
+  int32_t GetSampleRate() const;
+
+ private:
+  std::unique_ptr<OfflineSpeechDenoiserImpl> impl_;
+};
+
+}  // namespace sherpa_onnx
+
+#endif  // SHERPA_ONNX_CSRC_OFFLINE_SPEECH_DENOISER_H_