Extract bitrate allocation of spatial/temporal layers out of codec impl.

webrtc/modules/video_coding/utility/default_video_bitrate_allocator.cc

+/*
+ *  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/video_coding/utility/default_video_bitrate_allocator.h"
+#include "webrtc/base/basictypes.h"
+#include "webrtc/base/constructormagic.h"
+
+namespace webrtc {
+
+DefaultVideoBitrateAllocator::DefaultVideoBitrateAllocator(
+    const VideoCodec& codec)
+    : codec_(codec) {}
+
+DefaultVideoBitrateAllocator::~DefaultVideoBitrateAllocator() {}
+
+BitrateAllocation DefaultVideoBitrateAllocator::GetAllocation(
+    uint32_t total_bitrate_bps,
+    uint32_t framerate) {
+  BitrateAllocation allocation;
+  if (total_bitrate_bps == 0)
+    return allocation;
+
+  if (total_bitrate_bps < codec_.minBitrate * 1000) {
+    allocation.SetBitrate(0, 0, codec_.minBitrate * 1000);
+  } else if (codec_.maxBitrate > 0 &&
+             total_bitrate_bps > codec_.maxBitrate * 1000) {
+    allocation.SetBitrate(0, 0, codec_.maxBitrate * 1000);
+  } else {
+    allocation.SetBitrate(0, 0, total_bitrate_bps);
+  }
+
+  return allocation;
+}
+
+uint32_t DefaultVideoBitrateAllocator::GetPreferedBitrate(int frame_rate) {
+  return GetAllocation(codec_.maxBitrate, frame_rate).get_sum_kbps();
+}
+
+}  // namespace webrtc