The default logic for creating video bitrate allocator.

It is a mirror of `VideoCodecInitializer::CreateBitrateAllocator`

Bug: webrtc:9513
Change-Id: Ib2e83e9f757387a2f6f6101d5d21512f1d507a95
Reviewed-on: https://webrtc-review.googlesource.com/92320
Commit-Queue: Jiawei Ou <ouj@fb.com>
Reviewed-by: Tommi <tommi@webrtc.org>
Reviewed-by: Erik Språng <sprang@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#24413}

api/video/BUILD.gn

@@ -108,7 +108,7 @@ rtc_source_set("video_bitrate_allocator_factory") {
   ]
   deps = [
     ":video_bitrate_allocator",
-    "../../media:rtc_media_base",
+    "../video_codecs:video_codecs_api",
   ]
 }
 

api/video/video_bitrate_allocator_factory.h

@@ -13,7 +13,7 @@
 
 #include <memory>
 #include "api/video/video_bitrate_allocator.h"
-#include "media/base/codec.h"
+#include "api/video_codecs/video_codec.h"
 
 namespace webrtc {
 

pc/BUILD.gn

@@ -214,6 +214,23 @@ rtc_static_library("peerconnection") {
   ]
 }
 
+rtc_static_library("builtin_video_bitrate_allocator_factory") {
+  sources = [
+    "builtin_video_bitrate_allocator_factory.cc",
+    "builtin_video_bitrate_allocator_factory.h",
+  ]
+
+  deps = [
+    "../api/video:video_bitrate_allocator_factory",
+    "../media:rtc_media_base",
+    "../modules/video_coding:video_coding_utility",
+    "../modules/video_coding:webrtc_vp9_helpers",
+    "../rtc_base:ptr_util",
+    "../rtc_base/system:fallthrough",
+    "//third_party/abseil-cpp/absl/memory",
+  ]
+}
+
 # This target implements CreatePeerConnectionFactory methods that will create a
 # PeerConnection will full functionality (audio, video and data). Applications
 # that wish to reduce their binary size by ommitting functionality they don't

pc/builtin_video_bitrate_allocator_factory.cc

@@ -0,0 +1,56 @@
+/*
+ *  Copyright (c) 2018 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 "pc/builtin_video_bitrate_allocator_factory.h"
+
+#include "absl/memory/memory.h"
+#include "media/base/codec.h"
+#include "modules/video_coding/codecs/vp9/svc_rate_allocator.h"
+#include "modules/video_coding/utility/default_video_bitrate_allocator.h"
+#include "modules/video_coding/utility/simulcast_rate_allocator.h"
+#include "rtc_base/system/fallthrough.h"
+
+namespace webrtc {
+
+namespace {
+
+class BuiltinVideoBitrateAllocatorFactory
+    : public VideoBitrateAllocatorFactory {
+ public:
+  BuiltinVideoBitrateAllocatorFactory() = default;
+  ~BuiltinVideoBitrateAllocatorFactory() override = default;
+
+  std::unique_ptr<VideoBitrateAllocator> CreateVideoBitrateAllocator(
+      const VideoCodec& codec) override {
+    std::unique_ptr<VideoBitrateAllocator> rate_allocator;
+    switch (codec.codecType) {
+      case kVideoCodecVP8:
+        RTC_FALLTHROUGH();
+      case kVideoCodecH264:
+        rate_allocator.reset(new SimulcastRateAllocator(codec));
+        break;
+      case kVideoCodecVP9:
+        rate_allocator.reset(new SvcRateAllocator(codec));
+        break;
+      default:
+        rate_allocator.reset(new DefaultVideoBitrateAllocator(codec));
+    }
+    return rate_allocator;
+  }
+};
+
+}  // namespace
+
+std::unique_ptr<VideoBitrateAllocatorFactory>
+CreateBuiltinVideoBitrateAllocatorFactory() {
+  return absl::make_unique<BuiltinVideoBitrateAllocatorFactory>();
+}
+
+}  // namespace webrtc

pc/builtin_video_bitrate_allocator_factory.h

@@ -0,0 +1,25 @@
+/*
+ *  Copyright (c) 2018 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.
+ */
+
+#ifndef PC_BUILTIN_VIDEO_BITRATE_ALLOCATOR_FACTORY_H_
+#define PC_BUILTIN_VIDEO_BITRATE_ALLOCATOR_FACTORY_H_
+
+#include <memory>
+
+#include "api/video/video_bitrate_allocator_factory.h"
+
+namespace webrtc {
+
+std::unique_ptr<VideoBitrateAllocatorFactory>
+CreateBuiltinVideoBitrateAllocatorFactory();
+
+}  // namespace webrtc
+
+#endif  // PC_BUILTIN_VIDEO_BITRATE_ALLOCATOR_FACTORY_H_