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Add CTC HLG decoding using OpenFst (#349)

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This commit is contained in:
Fangjun Kuang
2023-10-08 11:32:39 +08:00
committed by GitHub
parent c12286fe5e
commit 407602445d
39 changed files with 964 additions and 56 deletions
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25
sherpa-onnx/csrc/offline-recognizer-ctc-impl.h
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@@ -16,6 +16,7 @@
#endif
#include "sherpa-onnx/csrc/offline-ctc-decoder.h"
#include "sherpa-onnx/csrc/offline-ctc-fst-decoder.h"
#include "sherpa-onnx/csrc/offline-ctc-greedy-search-decoder.h"
#include "sherpa-onnx/csrc/offline-ctc-model.h"
#include "sherpa-onnx/csrc/offline-recognizer-impl.h"
@@ -25,9 +26,12 @@
namespace sherpa_onnx {
static OfflineRecognitionResult Convert(const OfflineCtcDecoderResult &src,
const SymbolTable &sym_table) {
const SymbolTable &sym_table,
int32_t frame_shift_ms,
int32_t subsampling_factor) {
OfflineRecognitionResult r;
r.tokens.reserve(src.tokens.size());
r.timestamps.reserve(src.timestamps.size());
std::string text;
@@ -42,6 +46,12 @@ static OfflineRecognitionResult Convert(const OfflineCtcDecoderResult &src,
}
r.text = std::move(text);
float frame_shift_s = frame_shift_ms / 1000. * subsampling_factor;
for (auto t : src.timestamps) {
float time = frame_shift_s * t;
r.timestamps.push_back(time);
}
return r;
}
@@ -68,7 +78,12 @@ class OfflineRecognizerCtcImpl : public OfflineRecognizerImpl {
config_.feat_config.nemo_normalize_type =
model_->FeatureNormalizationMethod();
if (config_.decoding_method == "greedy_search") {
if (!config_.ctc_fst_decoder_config.graph.empty()) {
// TODO(fangjun): Support android to read the graph from
// asset_manager
decoder_ = std::make_unique<OfflineCtcFstDecoder>(
config_.ctc_fst_decoder_config);
} else if (config_.decoding_method == "greedy_search") {
if (!symbol_table_.contains("<blk>") &&
!symbol_table_.contains("<eps>")) {
SHERPA_ONNX_LOGE(
@@ -139,10 +154,12 @@ class OfflineRecognizerCtcImpl : public OfflineRecognizerImpl {
-23.025850929940457f);
auto t = model_->Forward(std::move(x), std::move(x_length));
auto results = decoder_->Decode(std::move(t.first), std::move(t.second));
auto results = decoder_->Decode(std::move(t[0]), std::move(t[1]));
int32_t frame_shift_ms = 10;
for (int32_t i = 0; i != n; ++i) {
auto r = Convert(results[i], symbol_table_);
auto r = Convert(results[i], symbol_table_, frame_shift_ms,
model_->SubsamplingFactor());
ss[i]->SetResult(r);
}
}