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95 lines
2.7 KiB
C++
95 lines
2.7 KiB
C++
// sherpa-onnx/csrc/rknn/online-transducer-greedy-search-decoder-rknn.cc
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//
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// Copyright (c) 2025 Xiaomi Corporation
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#include "sherpa-onnx/csrc/rknn/online-transducer-greedy-search-decoder-rknn.h"
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#include <algorithm>
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#include <utility>
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#include <vector>
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#include "sherpa-onnx/csrc/macros.h"
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namespace sherpa_onnx {
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OnlineTransducerDecoderResultRknn
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OnlineTransducerGreedySearchDecoderRknn::GetEmptyResult() const {
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int32_t context_size = model_->ContextSize();
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int32_t blank_id = 0; // always 0
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OnlineTransducerDecoderResultRknn r;
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r.tokens.resize(context_size, -1);
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r.tokens.back() = blank_id;
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return r;
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}
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void OnlineTransducerGreedySearchDecoderRknn::StripLeadingBlanks(
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OnlineTransducerDecoderResultRknn *r) const {
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int32_t context_size = model_->ContextSize();
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auto start = r->tokens.begin() + context_size;
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auto end = r->tokens.end();
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r->tokens = std::vector<int64_t>(start, end);
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}
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void OnlineTransducerGreedySearchDecoderRknn::Decode(
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std::vector<float> encoder_out,
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OnlineTransducerDecoderResultRknn *result) const {
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auto &r = result[0];
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auto attr = model_->GetEncoderOutAttr();
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int32_t num_frames = attr.dims[1];
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int32_t encoder_out_dim = attr.dims[2];
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int32_t vocab_size = model_->VocabSize();
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int32_t context_size = model_->ContextSize();
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std::vector<int64_t> decoder_input;
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std::vector<float> decoder_out;
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if (r.previous_decoder_out.empty()) {
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decoder_input = {r.tokens.begin() + (r.tokens.size() - context_size),
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r.tokens.end()};
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decoder_out = model_->RunDecoder(std::move(decoder_input));
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} else {
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decoder_out = std::move(r.previous_decoder_out);
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}
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const float *p_encoder_out = encoder_out.data();
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for (int32_t t = 0; t != num_frames; ++t) {
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auto logit = model_->RunJoiner(p_encoder_out, decoder_out.data());
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p_encoder_out += encoder_out_dim;
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bool emitted = false;
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if (blank_penalty_ > 0.0) {
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logit[0] -= blank_penalty_; // assuming blank id is 0
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}
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auto y = static_cast<int32_t>(std::distance(
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logit.data(),
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std::max_element(logit.data(), logit.data() + vocab_size)));
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// blank id is hardcoded to 0
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// also, it treats unk as blank
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if (y != 0 && y != unk_id_) {
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emitted = true;
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r.tokens.push_back(y);
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r.timestamps.push_back(t + r.frame_offset);
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r.num_trailing_blanks = 0;
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} else {
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++r.num_trailing_blanks;
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}
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if (emitted) {
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decoder_input = {r.tokens.begin() + (r.tokens.size() - context_size),
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r.tokens.end()};
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decoder_out = model_->RunDecoder(std::move(decoder_input));
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}
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}
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r.frame_offset += num_frames;
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r.previous_decoder_out = std::move(decoder_out);
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}
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} // namespace sherpa_onnx
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