Add BufferedLabelScorer (#88)

src/Nn/LabelScorer/BufferedLabelScorer.cc

@@ -0,0 +1,49 @@
+/** Copyright 2025 RWTH Aachen University. All rights reserved.
+ *
+ *  Licensed under the RWTH ASR License (the "License");
+ *  you may not use this file except in compliance with the License.
+ *  You may obtain a copy of the License at
+ *
+ *      http://www.hltpr.rwth-aachen.de/rwth-asr/rwth-asr-license.html
+ *
+ *  Unless required by applicable law or agreed to in writing, software
+ *  distributed under the License is distributed on an "AS IS" BASIS,
+ *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ *  See the License for the specific language governing permissions and
+ *  limitations under the License.
+ */
+
+#include "BufferedLabelScorer.hh"
+
+namespace Nn {
+
+BufferedLabelScorer::BufferedLabelScorer(Core::Configuration const& config)
+        : Core::Component(config),
+          Precursor(config),
+          inputBuffer_(),
+          featureSize_(Core::Type<size_t>::max),
+          expectMoreFeatures_(true) {
+}
+
+void BufferedLabelScorer::reset() {
+    inputBuffer_.clear();
+    featureSize_        = Core::Type<size_t>::max;
+    expectMoreFeatures_ = true;
+}
+
+void BufferedLabelScorer::signalNoMoreFeatures() {
+    expectMoreFeatures_ = false;
+}
+
+void BufferedLabelScorer::addInput(std::shared_ptr<const f32[]> const& input, size_t featureSize) {
+    if (featureSize_ == Core::Type<size_t>::max) {
+        featureSize_ = featureSize;
+    }
+    else if (featureSize_ != featureSize) {
+        error() << "Label scorer received incompatible feature size " << featureSize << "; was set to " << featureSize_ << " before.";
+    }
+
+    inputBuffer_.push_back(input);
+}
+
+}  // namespace Nn

src/Nn/LabelScorer/BufferedLabelScorer.hh

@@ -0,0 +1,52 @@
+/** Copyright 2025 RWTH Aachen University. All rights reserved.
+ *
+ *  Licensed under the RWTH ASR License (the "License");
+ *  you may not use this file except in compliance with the License.
+ *  You may obtain a copy of the License at
+ *
+ *      http://www.hltpr.rwth-aachen.de/rwth-asr/rwth-asr-license.html
+ *
+ *  Unless required by applicable law or agreed to in writing, software
+ *  distributed under the License is distributed on an "AS IS" BASIS,
+ *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ *  See the License for the specific language governing permissions and
+ *  limitations under the License.
+ */
+
+#ifndef BUFFERED_LABEL_SCORER_HH
+#define BUFFERED_LABEL_SCORER_HH
+
+#include "LabelScorer.hh"
+
+namespace Nn {
+
+/*
+ * Extension of `LabelScorer` that implements some commonly used buffering logic for input features
+ * and timeframes as well as a flag that indicates whether more features are expected to be added to the buffer.
+ * This serves as a base class for other LabelScorers.
+ */
+class BufferedLabelScorer : public LabelScorer {
+public:
+    using Precursor = LabelScorer;
+
+    BufferedLabelScorer(Core::Configuration const& config);
+
+    // Prepares the LabelScorer to receive new inputs by resetting input buffer, timeframe buffer
+    // and segment end flag
+    virtual void reset() override;
+
+    // Tells the LabelScorer that there will be no more input features coming in the current segment
+    virtual void signalNoMoreFeatures() override;
+
+    // Add a single input feature to the buffer
+    virtual void addInput(std::shared_ptr<const f32[]> const& input, size_t featureSize) override;
+
+protected:
+    std::vector<std::shared_ptr<const f32[]>> inputBuffer_;         // Buffer that contains all the feature data for the current segment
+    size_t                                    featureSize_;         // Feature dimension size of features in the buffer (same for all features)
+    bool                                      expectMoreFeatures_;  // Flag to record segment end signal
+};
+
+}  // namespace Nn
+
+#endif  // BUFFERED_LABEL_SCORER_HH

src/Nn/LabelScorer/Makefile

@@ -10,6 +10,7 @@ SUBDIRS		=
 TARGETS		= libSprintLabelScorer.$(a)
 
 LIBSPRINTLABELSCORER_O =  \
+    $(OBJDIR)/BufferedLabelScorer.o \
     $(OBJDIR)/LabelScorer.o \
     $(OBJDIR)/ScoringContext.o