Move dead submodules in-tree

Signed-off-by: swurl <swurl@swurl.xyz>

externals/oboe/src/flowgraph/MultiToMonoConverter.cpp

@@ -0,0 +1,41 @@
+/*
+ * Copyright 2015 The Android Open Source Project
+ *
+ * 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 <unistd.h>
+#include "FlowGraphNode.h"
+#include "MultiToMonoConverter.h"
+
+using namespace FLOWGRAPH_OUTER_NAMESPACE::flowgraph;
+
+MultiToMonoConverter::MultiToMonoConverter(int32_t inputChannelCount)
+        : input(*this, inputChannelCount)
+        , output(*this, 1) {
+}
+
+MultiToMonoConverter::~MultiToMonoConverter() = default;
+
+int32_t MultiToMonoConverter::onProcess(int32_t numFrames) {
+    const float *inputBuffer = input.getBuffer();
+    float *outputBuffer = output.getBuffer();
+    int32_t channelCount = input.getSamplesPerFrame();
+    for (int i = 0; i < numFrames; i++) {
+        // read first channel of multi stream, write many
+        *outputBuffer++ = *inputBuffer;
+        inputBuffer += channelCount;
+    }
+    return numFrames;
+}
+