Added first layer of the echo canceller 3 functionality

webrtc/modules/audio_processing/aec3/block_framer.cc

Index: webrtc/modules/audio_processing/aec3/block_framer.cc
diff --git a/webrtc/modules/audio_processing/aec3/block_framer.cc b/webrtc/modules/audio_processing/aec3/block_framer.cc
new file mode 100644
index 0000000000000000000000000000000000000000..6425dae8c87551419fc30089155c65bdf5bbbedc
--- /dev/null
+++ b/webrtc/modules/audio_processing/aec3/block_framer.cc
@@ -0,0 +1,59 @@
+/*
+ *  Copyright (c) 2016 The WebRTC project authors. All Rights Reserved.
+ *
+ *  Use of this source code is governed by a BSD-style license
+ *  that can be found in the LICENSE file in the root of the source
+ *  tree. An additional intellectual property rights grant can be found
+ *  in the file PATENTS.  All contributing project authors may
+ *  be found in the AUTHORS file in the root of the source tree.
+ */
+
+#include "webrtc/modules/audio_processing/aec3/block_framer.h"
+
+#include <algorithm>
+
+#include "webrtc/base/checks.h"
+
+namespace webrtc {
+
+BlockFramer::BlockFramer(size_t num_bands)
+    : num_bands_(num_bands),
+      buffer_(num_bands_, std::vector<float>(kBlockSize, 0.f)) {}
+
+BlockFramer::~BlockFramer() = default;
+
+// All the constants are chosen so that the buffer is either empty or has enough
+// samples for InsertBlockAndExtractSubFrame to produce a frame. In order to
+// achieve this, the InsertBlockAndExtractSubFrame and InsertBlock methods need
+// to be called in the correct order.
+void BlockFramer::InsertBlock(const std::vector<std::vector<float>>& block) {
+  RTC_DCHECK_EQ(num_bands_, block.size());
+  for (size_t i = 0; i < num_bands_; ++i) {
+    RTC_DCHECK_EQ(kBlockSize, block[i].size());
+    RTC_DCHECK_EQ(0, buffer_[i].size());
+    buffer_[i].insert(buffer_[i].begin(), block[i].begin(), block[i].end());
+  }
+}
+
+void BlockFramer::InsertBlockAndExtractSubFrame(
+    const std::vector<std::vector<float>>& block,
+    std::vector<rtc::ArrayView<float>>* sub_frame) {
+  RTC_DCHECK(sub_frame);
+  RTC_DCHECK_EQ(num_bands_, block.size());
+  RTC_DCHECK_EQ(num_bands_, sub_frame->size());
+  for (size_t i = 0; i < num_bands_; ++i) {
+    RTC_DCHECK_LE(kSubFrameLength, buffer_[i].size() + kBlockSize);
+    RTC_DCHECK_EQ(kBlockSize, block[i].size());
+    RTC_DCHECK_GE(kBlockSize, buffer_[i].size());
+    RTC_DCHECK_EQ(kSubFrameLength, (*sub_frame)[i].size());
+    const int samples_to_frame = kSubFrameLength - buffer_[i].size();
+    std::copy(buffer_[i].begin(), buffer_[i].end(), (*sub_frame)[i].begin());
+    std::copy(block[i].begin(), block[i].begin() + samples_to_frame,
+              (*sub_frame)[i].begin() + buffer_[i].size());
+    buffer_[i].clear();
+    buffer_[i].insert(buffer_[i].begin(), block[i].begin() + samples_to_frame,
+                      block[i].end());
+  }
+}
+
+}  // namespace webrtc