55 lines
1.6 KiB
C++
55 lines
1.6 KiB
C++
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// sherpa-onnx/csrc/offline-ctc-greedy-search-decoder.h
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//
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// Copyright (c) 2023 Xiaomi Corporation
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#include "sherpa-onnx/csrc/offline-ctc-greedy-search-decoder.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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std::vector<OfflineCtcDecoderResult> OfflineCtcGreedySearchDecoder::Decode(
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Ort::Value log_probs, Ort::Value log_probs_length) {
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std::vector<int64_t> shape = log_probs.GetTensorTypeAndShapeInfo().GetShape();
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int32_t batch_size = static_cast<int32_t>(shape[0]);
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int32_t num_frames = static_cast<int32_t>(shape[1]);
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int32_t vocab_size = static_cast<int32_t>(shape[2]);
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const int64_t *p_log_probs_length = log_probs_length.GetTensorData<int64_t>();
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std::vector<OfflineCtcDecoderResult> ans;
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ans.reserve(batch_size);
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for (int32_t b = 0; b != batch_size; ++b) {
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const float *p_log_probs =
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log_probs.GetTensorData<float>() + b * num_frames * vocab_size;
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OfflineCtcDecoderResult r;
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int64_t prev_id = -1;
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for (int32_t t = 0; t != static_cast<int32_t>(p_log_probs_length[b]); ++t) {
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auto y = static_cast<int64_t>(std::distance(
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static_cast<const float *>(p_log_probs),
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std::max_element(
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static_cast<const float *>(p_log_probs),
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static_cast<const float *>(p_log_probs) + vocab_size)));
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p_log_probs += vocab_size;
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if (y != blank_id_ && y != prev_id) {
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r.tokens.push_back(y);
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r.timestamps.push_back(t);
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prev_id = y;
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}
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} // for (int32_t t = 0; ...)
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ans.push_back(std::move(r));
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}
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return ans;
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}
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} // namespace sherpa_onnx
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