CTCGreedyDecoder layer op (#2965)

* Added CTCGreedyDecoder layer op

* Added comment on seq_len validation checks

src/ngraph/CMakeLists.txt

@@ -168,6 +168,8 @@ set (SRC
     op/experimental/quantized_dot_bias.hpp
     op/experimental/transpose.cpp
     op/experimental/transpose.hpp
+    op/experimental/layers/ctc_greedy_decoder.cpp
+    op/experimental/layers/ctc_greedy_decoder.hpp
     op/experimental/layers/detection_output.cpp
     op/experimental/layers/detection_output.hpp
     op/experimental/layers/interpolate.cpp

src/ngraph/op/experimental/layers/ctc_greedy_decoder.cpp

+//*****************************************************************************
+// Copyright 2017-2019 Intel Corporation
+//
+// Licensed under the Apache License, Version 2.0 (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.apache.org/licenses/LICENSE-2.0
+//
+// 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 "ctc_greedy_decoder.hpp"
+
+using namespace std;
+using namespace ngraph;
+
+op::CTCGreedyDecoder::CTCGreedyDecoder(const shared_ptr<Node>& input,
+                                       const std::shared_ptr<Node>& seq_len,
+                                       const bool ctc_merge_repeated)
+    : Op("CTCGreedyDecoder", check_single_output_args({input, seq_len}))
+    , m_ctc_merge_repeated(ctc_merge_repeated)
+{
+    constructor_validate_and_infer_types();
+}
+
+void op::CTCGreedyDecoder::validate_and_infer_types()
+{
+    auto input_et = get_input_element_type(0);
+    if (get_input_partial_shape(0).is_static())
+    {
+        Shape input_shape = get_input_partial_shape(0).to_shape();
+        NODE_VALIDATION_CHECK(this,
+                              input_shape.size() >= 3,
+                              "CTCGreedyDecoder expects 3 or more dimensions for input. Got ",
+                              input_shape.size());
+        // TODO: Add more validation checks for seq_len
+
+        set_output_type(0, input_et, Shape{input_shape[1], input_shape[0], 1, 1});
+    }
+    else
+    {
+        set_output_type(0, input_et, PartialShape::dynamic());
+    }
+}
+
+shared_ptr<Node> op::CTCGreedyDecoder::copy_with_new_args(const NodeVector& new_args) const
+{
+    check_new_args_count(this, new_args);
+    return make_shared<CTCGreedyDecoder>(new_args.at(0), new_args.at(1), m_ctc_merge_repeated);
+}

src/ngraph/op/experimental/layers/ctc_greedy_decoder.hpp

+//*****************************************************************************
+// Copyright 2017-2019 Intel Corporation
+//
+// Licensed under the Apache License, Version 2.0 (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.apache.org/licenses/LICENSE-2.0
+//
+// 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.
+//*****************************************************************************
+
+#pragma once
+
+#include "ngraph/op/op.hpp"
+
+namespace ngraph
+{
+    namespace op
+    {
+        class CTCGreedyDecoder : public Op
+        {
+        public:
+            /// \brief Constructs a CTCGreedyDecoder operation
+            ///
+            /// \param input              Logits on which greedy decoding is performed
+            /// \param seq_len            Sequence lengths
+            /// \param ctc_merge_repeated Whether to merge repeated labels
+            CTCGreedyDecoder(const std::shared_ptr<Node>& input,
+                             const std::shared_ptr<Node>& seq_len,
+                             const bool ctc_merge_repeated);
+
+            void validate_and_infer_types() override;
+
+            virtual std::shared_ptr<Node>
+                copy_with_new_args(const NodeVector& new_args) const override;
+
+            bool get_ctc_merge_repeated() const { return m_ctc_merge_repeated; }
+        private:
+            bool m_ctc_merge_repeated;
+        };
+    }
+}

test/type_prop_layers.cpp

@@ -17,6 +17,7 @@
 #include "gtest/gtest.h"
 
 #include "ngraph/ngraph.hpp"
+#include "ngraph/op/experimental/layers/ctc_greedy_decoder.hpp"
 #include "ngraph/op/experimental/layers/detection_output.hpp"
 #include "ngraph/op/experimental/layers/interpolate.hpp"
 #include "ngraph/op/experimental/layers/prior_box.hpp"
@@ -31,6 +32,14 @@
 using namespace std;
 using namespace ngraph;
 
+TEST(type_prop_layers, ctc_greedy_decoder)
+{
+    auto input = make_shared<op::Parameter>(element::f32, Shape{88, 2, 48, 1});
+    auto seq_len = make_shared<op::Parameter>(element::f32, Shape{88, 2});
+    auto op = make_shared<op::CTCGreedyDecoder>(input, seq_len, false);
+    ASSERT_EQ(op->get_shape(), (Shape{2, 88, 1, 1}));
+}
+
 TEST(type_prop_layers, detection_output)
 {
     auto box_logits = make_shared<op::Parameter>(element::f32, Shape{4, 1, 5, 5});