Support whisper models (#238)

sherpa-onnx/csrc/offline-whisper-decoder.h

@@ -0,0 +1,38 @@
+// sherpa-onnx/csrc/offline-whisper-decoder.h
+//
+// Copyright (c)  2023  Xiaomi Corporation
+
+#ifndef SHERPA_ONNX_CSRC_OFFLINE_WHISPER_DECODER_H_
+#define SHERPA_ONNX_CSRC_OFFLINE_WHISPER_DECODER_H_
+
+#include <vector>
+
+#include "onnxruntime_cxx_api.h"  // NOLINT
+
+namespace sherpa_onnx {
+
+struct OfflineWhisperDecoderResult {
+  /// The decoded token IDs
+  std::vector<int32_t> tokens;
+};
+
+class OfflineWhisperDecoder {
+ public:
+  virtual ~OfflineWhisperDecoder() = default;
+
+  /** Run beam search given the output from the whisper encoder model.
+   *
+   * @param n_layer_cross_k       A 4-D tensor of shape
+   *                              (n_text_layer, N, n_audio_ctx, n_text_state).
+   * @param n_layer_cross_v       A 4-D tensor of shape
+   *                              (n_text_layer, N, n_audio_ctx, n_text_state).
+   *
+   * @return Return a vector of size `N` containing the decoded results.
+   */
+  virtual std::vector<OfflineWhisperDecoderResult> Decode(
+      Ort::Value n_layer_cross_k, Ort::Value n_layer_cross_v) = 0;
+};
+
+}  // namespace sherpa_onnx
+
+#endif  // SHERPA_ONNX_CSRC_OFFLINE_WHISPER_DECODER_H_