online-ctc-greedy-search-decoder.cc
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// sherpa-onnx/csrc/online-ctc-greedy-search-decoder.cc
//
// Copyright (c) 2023 Xiaomi Corporation
#include "sherpa-onnx/csrc/online-ctc-greedy-search-decoder.h"
#include <algorithm>
#include <utility>
#include <vector>
#include "sherpa-onnx/csrc/macros.h"
namespace sherpa_onnx {
void OnlineCtcGreedySearchDecoder::Decode(
const float *log_probs, int32_t batch_size, int32_t num_frames,
int32_t vocab_size, std::vector<OnlineCtcDecoderResult> *results,
OnlineStream ** /*ss=nullptr*/, int32_t /*n = 0*/) {
if (batch_size != results->size()) {
SHERPA_ONNX_LOGE("Size mismatch! log_probs.size(0) %d, results.size(0): %d",
batch_size, static_cast<int32_t>(results->size()));
exit(-1);
}
const float *p = log_probs;
for (int32_t b = 0; b != batch_size; ++b) {
auto &r = (*results)[b];
int32_t prev_id = -1;
if (!r.tokens.empty()) {
if (r.num_trailing_blanks > 0) {
prev_id = blank_id_;
} else {
prev_id = r.tokens.back();
}
}
for (int32_t t = 0; t != num_frames; ++t, p += vocab_size) {
int32_t y = static_cast<int32_t>(std::distance(
static_cast<const float *>(p),
std::max_element(static_cast<const float *>(p),
static_cast<const float *>(p) + vocab_size)));
if (y == blank_id_) {
r.num_trailing_blanks += 1;
} else {
r.num_trailing_blanks = 0;
}
if (y != blank_id_ && y != prev_id) {
r.tokens.push_back(y);
r.timestamps.push_back(t + r.frame_offset);
}
prev_id = y;
} // for (int32_t t = 0; t != num_frames; ++t) {
} // for (int32_t b = 0; b != batch_size; ++b)
// Update frame_offset
for (auto &r : *results) {
r.frame_offset += num_frames;
}
}
} // namespace sherpa_onnx