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

webrtc/modules/video_coding/video_bitrate_allocator_factory.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/include/video_bitrate_allocator_factory.h"
+
+#include "webrtc/base/basictypes.h"
+#include "webrtc/common_video/include/video_bitrate_allocator.h"
+#include "webrtc/common_types.h"
+#include "webrtc/modules/video_coding/codecs/vp8/screenshare_layers.h"
+#include "webrtc/modules/video_coding/codecs/vp8/temporal_layers.h"
+#include "webrtc/modules/video_coding/utility/simulcast_rate_allocator.h"
+#include "webrtc/modules/video_coding/utility/default_video_bitrate_allocator.h"
+#include "webrtc/system_wrappers/include/clock.h"
+
+namespace webrtc {
+
+struct ScreenshareTemporalLayersFactory : webrtc::TemporalLayersFactory {
+  ScreenshareTemporalLayersFactory() {}
+  virtual ~ScreenshareTemporalLayersFactory() {}
+
+  virtual webrtc::TemporalLayers* Create(int simulcast_id,
+                                         int num_temporal_layers,
+                                         uint8_t initial_tl0_pic_idx) const {
+    webrtc::TemporalLayers* tl = new webrtc::ScreenshareLayers(
+        num_temporal_layers, rand(), webrtc::Clock::GetRealTimeClock());
+    if (listener_)
+      listener_->OnTemporalLayersCreated(simulcast_id, tl);
+    return tl;
+  }
+};
+
+std::unique_ptr<VideoBitrateAllocator>
+VideoBitrateAllocatorFactory::GetBitrateAllocator(VideoCodec* codec) {

[perkj_webrtc, 2016/10/27 12:57:31]

it feels weird that GetBitrateAllocator take a none const pointer and also
modify it. 

I still think it would make sence if this method took a just the payload name
and created a VideoBitrateAllocator. 

The VideoBitrateAllocator can then construct the VideoCodec. In the VP8
VideoBitrateAllocator your can set codec->codecSpecific.VP8.tl_factory.

Change in ViEEncoder::ReconfigureVideoEncoder would be something like:

encoder_config_, streams, settings_.payload_name, settings_.payload_type

rate_allocator_.reset(VideoBitrateAllocatorFactory::GetBitrateAllocator(encoder_config_,
streams, settings_.payload_name,settings_.payload_type);
VideoCodec codec = rate_allocator->GetVideoCodec(); 

[sprang_webrtc, 2016/11/01 18:03:16]

I don't think it makes sense to have the rate allocator itself create the
VideoCodec instance.
I changed this class instead to VideoCodecInitializer, which can handle all of
VideoEncoderConfigToVideoCodec() for vie_encoder, and also creates the
VideoBitrateAllocator which goes with that.
Makes sense?

+  std::unique_ptr<VideoBitrateAllocator> rate_allocator;
+
+  switch (codec->codecType) {
+    case kVideoCodecVP8: {
+      // Set up default VP8 temporal layer factory, if not provided.
+      std::unique_ptr<TemporalLayersFactory> tl_factory;
+      if (!codec->codecSpecific.VP8.tl_factory) {
+        if (codec->mode == kScreensharing &&
+            codec->numberOfSimulcastStreams == 1 &&
+            codec->codecSpecific.VP8.numberOfTemporalLayers == 2) {
+          // Conference mode temporal layering for screen content.
+          tl_factory.reset(new ScreenshareTemporalLayersFactory());
+        } else {
+          // Standard video temporal layers.
+          tl_factory.reset(new TemporalLayersFactory());
+        }
+        codec->codecSpecific.VP8.tl_factory = tl_factory.get();
+      }
+      rate_allocator.reset(
+          new SimulcastRateAllocator(*codec, std::move(tl_factory)));
+      codec->codecSpecific.VP8.tl_factory->SetListener(
+          static_cast<SimulcastRateAllocator*>(rate_allocator.get()));
+    } break;
+    default:
+      rate_allocator.reset(new DefaultVideoBitrateAllocator(*codec));
+  }
+
+  return rate_allocator;
+}
+
+}  // namespace webrtc