Add non-streaming ASR (#92)

sherpa-onnx/csrc/offline-recognizer.h

@@ -0,0 +1,87 @@
+// sherpa-onnx/csrc/offline-recognizer.h
+//
+// Copyright (c)  2023  Xiaomi Corporation
+
+#ifndef SHERPA_ONNX_CSRC_OFFLINE_RECOGNIZER_H_
+#define SHERPA_ONNX_CSRC_OFFLINE_RECOGNIZER_H_
+
+#include <memory>
+#include <string>
+#include <vector>
+
+#include "sherpa-onnx/csrc/offline-stream.h"
+#include "sherpa-onnx/csrc/offline-transducer-model-config.h"
+#include "sherpa-onnx/csrc/parse-options.h"
+
+namespace sherpa_onnx {
+
+struct OfflineRecognitionResult {
+  // Recognition results.
+  // For English, it consists of space separated words.
+  // For Chinese, it consists of Chinese words without spaces.
+  std::string text;
+
+  // Decoded results at the token level.
+  // For instance, for BPE-based models it consists of a list of BPE tokens.
+  std::vector<std::string> tokens;
+
+  /// timestamps.size() == tokens.size()
+  /// timestamps[i] records the time in seconds when tokens[i] is decoded.
+  std::vector<float> timestamps;
+};
+
+struct OfflineRecognizerConfig {
+  OfflineFeatureExtractorConfig feat_config;
+  OfflineTransducerModelConfig model_config;
+
+  std::string decoding_method = "greedy_search";
+  // only greedy_search is implemented
+  // TODO(fangjun): Implement modified_beam_search
+
+  OfflineRecognizerConfig() = default;
+  OfflineRecognizerConfig(const OfflineFeatureExtractorConfig &feat_config,
+                          const OfflineTransducerModelConfig &model_config,
+                          const std::string &decoding_method)
+      : feat_config(feat_config),
+        model_config(model_config),
+        decoding_method(decoding_method) {}
+
+  void Register(ParseOptions *po);
+  bool Validate() const;
+
+  std::string ToString() const;
+};
+
+class OfflineRecognizer {
+ public:
+  ~OfflineRecognizer();
+
+  explicit OfflineRecognizer(const OfflineRecognizerConfig &config);
+
+  /// Create a stream for decoding.
+  std::unique_ptr<OfflineStream> CreateStream() const;
+
+  /** Decode a single stream
+   *
+   * @param s The stream to decode.
+   */
+  void DecodeStream(OfflineStream *s) const {
+    OfflineStream *ss[1] = {s};
+    DecodeStreams(ss, 1);
+  }
+
+  /** Decode a list of streams.
+   *
+   * @param ss Pointer to an array of streams.
+   * @param n  Size of the input array.
+   */
+  void DecodeStreams(OfflineStream **ss, int32_t n) const;
+
+ private:
+  class Impl;
+  std::unique_ptr<Impl> impl_;
+};
+
+}  // namespace sherpa_onnx
+
+#endif  // SHERPA_ONNX_CSRC_OFFLINE_RECOGNIZER_H_