online-lm.h
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// sherpa-onnx/csrc/online-lm.h
//
// Copyright (c) 2023 Xiaomi Corporation
#ifndef SHERPA_ONNX_CSRC_ONLINE_LM_H_
#define SHERPA_ONNX_CSRC_ONLINE_LM_H_
#include <memory>
#include <utility>
#include <vector>
#include "onnxruntime_cxx_api.h" // NOLINT
#include "sherpa-onnx/csrc/hypothesis.h"
#include "sherpa-onnx/csrc/online-lm-config.h"
namespace sherpa_onnx {
class OnlineLM {
public:
virtual ~OnlineLM() = default;
static std::unique_ptr<OnlineLM> Create(const OnlineLMConfig &config);
virtual std::vector<Ort::Value> GetInitStates() = 0;
/** Rescore a batch of sentences.
*
* @param x A 2-D tensor of shape (N, L) with data type int64.
* @param y A 2-D tensor of shape (N, L) with data type int64.
* @param states It contains the states for the LM model
* @return Return a pair containingo
* - negative loglike
* - updated states
*
* Caution: It returns negative log likelihood (nll), not log likelihood
*/
virtual std::pair<Ort::Value, std::vector<Ort::Value>> Rescore(
Ort::Value x, Ort::Value y, std::vector<Ort::Value> states) = 0;
// This function updates hyp.lm_lob_prob of hyps.
//
// @param scale LM score
// @param context_size Context size of the transducer decoder model
// @param hyps It is changed in-place.
void ComputeLMScore(float scale, int32_t context_size,
std::vector<Hypotheses> *hyps);
};
} // namespace sherpa_onnx
#endif // SHERPA_ONNX_CSRC_ONLINE_LM_H_