Add a C# api for offline-recognizer of sherpa-onnx (#129)

sherpa-onnx/csharp-api/offline-api.h

@@ -0,0 +1,122 @@
+// sherpa-onnx/sharp-api/offline-api.h
+//
+// Copyright (c)  2023  Manyeyes Corporation
+
+#pragma once
+
+#include <list>
+
+namespace sherpa_onnx
+{
+	/// Please refer to
+	/// https://k2-fsa.github.io/sherpa/onnx/pretrained_models/index.html
+	/// to download pre-trained models. That is, you can find encoder-xxx.onnx
+	/// decoder-xxx.onnx, joiner-xxx.onnx, and tokens.txt for this struct
+	/// from there.
+	typedef struct SherpaOnnxOfflineTransducer {
+		const char* encoder_filename;
+		const char* decoder_filename;
+		const char* joiner_filename;
+	} SherpaOnnxOfflineTransducer;
+
+	typedef struct SherpaOnnxOfflineParaformer {
+		const char* model;
+	}SherpaOnnxOfflineParaformer;
+
+	typedef struct SherpaOnnxOfflineNemoEncDecCtc {
+		const char* model;
+	}SherpaOnnxOfflineNemoEncDecCtc;
+
+
+	typedef struct SherpaOnnxOfflineModelConfig {
+		SherpaOnnxOfflineTransducer transducer;
+		SherpaOnnxOfflineParaformer paraformer;
+		SherpaOnnxOfflineNemoEncDecCtc nemo_ctc;
+		const char* tokens;
+		const int32_t num_threads;
+		const bool debug;
+	} SherpaOnnxOfflineModelConfig;
+
+	/// It expects 16 kHz 16-bit single channel wave format.
+	typedef struct SherpaOnnxFeatureConfig {
+		/// Sample rate of the input data. MUST match the one expected
+		/// by the model. For instance, it should be 16000 for models provided
+		/// by us.
+		int32_t sample_rate;
+
+		/// Feature dimension of the model.
+		/// For instance, it should be 80 for models provided by us.
+		int32_t feature_dim;
+	} SherpaOnnxFeatureConfig;
+
+	typedef struct SherpaOnnxOfflineRecognizerConfig {
+		SherpaOnnxFeatureConfig feat_config;
+		SherpaOnnxOfflineModelConfig model_config;
+
+		/// Possible values are: greedy_search, modified_beam_search
+		const char* decoding_method;
+
+	} SherpaOnnxOfflineRecognizerConfig;
+
+	typedef struct SherpaOnnxOfflineRecognizerResult {
+		// Recognition results.
+		// For English, it consists of space separated words.
+		// For Chinese, it consists of Chinese words without spaces.
+		char* text;
+		int text_len;
+
+		// 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;
+	} SherpaOnnxOfflineRecognizerResult;
+
+	/// Note: OfflineRecognizer here means StreamingRecognizer.
+	/// It does not need to access the Internet during recognition.
+	/// Everything is run locally.
+	typedef struct SherpaOnnxOfflineRecognizer SherpaOnnxOfflineRecognizer;
+
+	typedef struct SherpaOnnxOfflineStream SherpaOnnxOfflineStream;
+
+	extern "C" __declspec(dllexport)
+		SherpaOnnxOfflineRecognizer * __stdcall  CreateOfflineRecognizer(
+			const SherpaOnnxOfflineRecognizerConfig * config);
+
+	extern "C" __declspec(dllexport)
+		SherpaOnnxOfflineStream * __stdcall CreateOfflineStream(
+			SherpaOnnxOfflineRecognizer * sherpaOnnxOfflineRecognizer);
+
+	extern "C" __declspec(dllexport)
+		void __stdcall AcceptWaveform(
+			SherpaOnnxOfflineStream * stream, int32_t sample_rate,
+			const float* samples, int32_t samples_size);
+
+	extern "C" __declspec(dllexport)
+		void __stdcall DecodeOfflineStream(
+			SherpaOnnxOfflineRecognizer * recognizer,
+			SherpaOnnxOfflineStream * stream);
+
+	extern "C" __declspec(dllexport)
+		void __stdcall DecodeMultipleOfflineStreams(
+			SherpaOnnxOfflineRecognizer * recognizer,
+			SherpaOnnxOfflineStream * *streams, int32_t n);
+
+	extern "C" __declspec(dllexport)
+		SherpaOnnxOfflineRecognizerResult * __stdcall GetOfflineStreamResult(
+			SherpaOnnxOfflineStream * stream);
+
+	extern "C" __declspec(dllexport)
+		void __stdcall DestroyOfflineRecognizer(
+			SherpaOnnxOfflineRecognizer * recognizer);
+
+	extern "C" __declspec(dllexport)
+		void __stdcall DestroyOfflineStream(
+			SherpaOnnxOfflineStream * stream);
+
+	extern "C" __declspec(dllexport)
+		void __stdcall DestroyOfflineRecognizerResult(
+			SherpaOnnxOfflineRecognizerResult * r);
+}// namespace sherpa_onnx