modules/video_coding/codecs/vp8/simulcast_rate_allocator.cc - src - Git at Google

 /*
  *  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 "modules/video_coding/codecs/vp8/simulcast_rate_allocator.h"

 #include <algorithm>
 #include <memory>
 #include <vector>
 #include <utility>

 #include "rtc_base/checks.h"

 namespace webrtc {

 SimulcastRateAllocator::SimulcastRateAllocator(
     const VideoCodec& codec,
     std::unique_ptr<TemporalLayersFactory> tl_factory)
     : codec_(codec), tl_factory_(std::move(tl_factory)) {
   if (tl_factory_.get())
     tl_factory_->SetListener(this);
 }

 void SimulcastRateAllocator::OnTemporalLayersCreated(int simulcast_id,
                                                      TemporalLayers* layers) {
   RTC_DCHECK(temporal_layers_.find(simulcast_id) == temporal_layers_.end());
   RTC_DCHECK(layers);
   temporal_layers_[simulcast_id] = layers;
 }

 BitrateAllocation SimulcastRateAllocator::GetAllocation(
     uint32_t total_bitrate_bps,
     uint32_t framerate) {
   BitrateAllocation allocated_bitrates_bps;
   DistributeAllocationToSimulcastLayers(total_bitrate_bps,
                                         &allocated_bitrates_bps);
   DistributeAllocationToTemporalLayers(framerate, &allocated_bitrates_bps);
   return allocated_bitrates_bps;
 }

 void SimulcastRateAllocator::DistributeAllocationToSimulcastLayers(
     uint32_t total_bitrate_bps,
     BitrateAllocation* allocated_bitrates_bps) {
   uint32_t left_to_allocate = total_bitrate_bps;
   if (codec_.maxBitrate && codec_.maxBitrate * 1000 < left_to_allocate)
     left_to_allocate = codec_.maxBitrate * 1000;

   if (codec_.numberOfSimulcastStreams == 0) {
     // No simulcast, just set the target as this has been capped already.
     if (codec_.active) {
       allocated_bitrates_bps->SetBitrate(
           0, 0, std::max(codec_.minBitrate * 1000, left_to_allocate));
     }
     return;
   }
   // Find the first active layer. We don't allocate to inactive layers.
   size_t active_layer = 0;
   for (; active_layer < codec_.numberOfSimulcastStreams; ++active_layer) {
     if (codec_.simulcastStream[active_layer].active) {
       // Found the first active layer.
       break;
     }
   }
   // All streams could be inactive, and nothing more to do.
   if (active_layer == codec_.numberOfSimulcastStreams) {
     return;
   }

   // Always allocate enough bitrate for the minimum bitrate of the first
   // active layer. Suspending below min bitrate is controlled outside the
   // codec implementation and is not overridden by this.
   left_to_allocate = std::max(
       codec_.simulcastStream[active_layer].minBitrate * 1000, left_to_allocate);

   // Begin by allocating bitrate to simulcast streams, putting all bitrate in
   // temporal layer 0. We'll then distribute this bitrate, across potential
   // temporal layers, when stream allocation is done.

   size_t top_active_layer = active_layer;
   // Allocate up to the target bitrate for each active simulcast layer.
   for (; active_layer < codec_.numberOfSimulcastStreams; ++active_layer) {
     const SimulcastStream& stream = codec_.simulcastStream[active_layer];
     if (!stream.active) {
       continue;
     }
     // If we can't allocate to the current layer we can't allocate to higher
     // layers because they require a higher minimum bitrate.
     if (left_to_allocate < stream.minBitrate * 1000) {
       break;
     }
     // We are allocating to this layer so it is the current active allocation.
     top_active_layer = active_layer;
     uint32_t allocation =
         std::min(left_to_allocate, stream.targetBitrate * 1000);
     allocated_bitrates_bps->SetBitrate(active_layer, 0, allocation);
     RTC_DCHECK_LE(allocation, left_to_allocate);
     left_to_allocate -= allocation;
   }

   // Next, try allocate remaining bitrate, up to max bitrate, in top active
   // stream.
   // TODO(sprang): Allocate up to max bitrate for all layers once we have a
   //               better idea of possible performance implications.
   if (left_to_allocate > 0) {
     const SimulcastStream& stream = codec_.simulcastStream[top_active_layer];
     uint32_t bitrate_bps =
         allocated_bitrates_bps->GetSpatialLayerSum(top_active_layer);
     uint32_t allocation =
         std::min(left_to_allocate, stream.maxBitrate * 1000 - bitrate_bps);
     bitrate_bps += allocation;
     RTC_DCHECK_LE(allocation, left_to_allocate);
     left_to_allocate -= allocation;
     allocated_bitrates_bps->SetBitrate(top_active_layer, 0, bitrate_bps);
   }
 }

 void SimulcastRateAllocator::DistributeAllocationToTemporalLayers(
     uint32_t framerate,
     BitrateAllocation* allocated_bitrates_bps) {
   const int num_spatial_streams =
       std::max(1, static_cast<int>(codec_.numberOfSimulcastStreams));

   // Finally, distribute the bitrate for the simulcast streams across the
   // available temporal layers.
   for (int simulcast_id = 0; simulcast_id < num_spatial_streams;
        ++simulcast_id) {
     // TODO(shampson): Consider adding a continue here if the simulcast stream
     //                 is inactive. Currently this is not added because the call
     //                 below to OnRatesUpdated changes the TemporalLayer's
     //                 state.
     auto tl_it = temporal_layers_.find(simulcast_id);
     if (tl_it == temporal_layers_.end())
       continue;  // TODO(sprang): If > 1 SS, assume default TL alloc?

     uint32_t target_bitrate_kbps =
         allocated_bitrates_bps->GetBitrate(simulcast_id, 0) / 1000;

     const uint32_t expected_allocated_bitrate_kbps = target_bitrate_kbps;
     RTC_DCHECK_EQ(
         target_bitrate_kbps,
         allocated_bitrates_bps->GetSpatialLayerSum(simulcast_id) / 1000);
     const int num_temporal_streams = std::max<uint8_t>(
         1, codec_.numberOfSimulcastStreams == 0
                ? codec_.VP8().numberOfTemporalLayers
                : codec_.simulcastStream[simulcast_id].numberOfTemporalLayers);

     uint32_t max_bitrate_kbps;
     // Legacy temporal-layered only screenshare, or simulcast screenshare
     // with legacy mode for simulcast stream 0.
     if (codec_.mode == kScreensharing && codec_.targetBitrate > 0 &&
         ((num_spatial_streams == 1 && num_temporal_streams == 2) ||  // Legacy.
          (num_spatial_streams > 1 && simulcast_id == 0))) {  // Simulcast.
       // TODO(holmer): This is a "temporary" hack for screensharing, where we
       // interpret the startBitrate as the encoder target bitrate. This is
       // to allow for a different max bitrate, so if the codec can't meet
       // the target we still allow it to overshoot up to the max before dropping
       // frames. This hack should be improved.
       int tl0_bitrate = std::min(codec_.targetBitrate, target_bitrate_kbps);
       max_bitrate_kbps = std::min(codec_.maxBitrate, target_bitrate_kbps);
       target_bitrate_kbps = tl0_bitrate;
     } else if (num_spatial_streams == 1) {
       max_bitrate_kbps = codec_.maxBitrate;
     } else {
       max_bitrate_kbps = codec_.simulcastStream[simulcast_id].maxBitrate;
     }

     std::vector<uint32_t> tl_allocation = tl_it->second->OnRatesUpdated(
         target_bitrate_kbps, max_bitrate_kbps, framerate);
     RTC_DCHECK_GT(tl_allocation.size(), 0);
     RTC_DCHECK_LE(tl_allocation.size(), num_temporal_streams);

     uint64_t tl_allocation_sum_kbps = 0;
     for (size_t tl_index = 0; tl_index < tl_allocation.size(); ++tl_index) {
       uint32_t layer_rate_kbps = tl_allocation[tl_index];
       if (layer_rate_kbps > 0) {
         allocated_bitrates_bps->SetBitrate(simulcast_id, tl_index,
                                            layer_rate_kbps * 1000);
       }
       tl_allocation_sum_kbps += layer_rate_kbps;
     }
     RTC_DCHECK_LE(tl_allocation_sum_kbps, expected_allocated_bitrate_kbps);
   }
 }

 uint32_t SimulcastRateAllocator::GetPreferredBitrateBps(uint32_t framerate) {
   // Create a temporary instance without temporal layers, as they may be
   // stateful, and updating the bitrate to max here can cause side effects.
   SimulcastRateAllocator temp_allocator(codec_, nullptr);
   BitrateAllocation allocation =
       temp_allocator.GetAllocation(codec_.maxBitrate * 1000, framerate);
   return allocation.get_sum_bps();
 }

 const VideoCodec& webrtc::SimulcastRateAllocator::GetCodec() const {
   return codec_;
 }

 }  // namespace webrtc
	/*
	* 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 "modules/video_coding/codecs/vp8/simulcast_rate_allocator.h"

	#include <algorithm>
	#include <memory>
	#include <vector>
	#include <utility>

	#include "rtc_base/checks.h"

	namespace webrtc {

	SimulcastRateAllocator::SimulcastRateAllocator(
	const VideoCodec& codec,
	std::unique_ptr<TemporalLayersFactory> tl_factory)
	: codec_(codec), tl_factory_(std::move(tl_factory)) {
	if (tl_factory_.get())
	tl_factory_->SetListener(this);
	}

	void SimulcastRateAllocator::OnTemporalLayersCreated(int simulcast_id,
	TemporalLayers* layers) {
	RTC_DCHECK(temporal_layers_.find(simulcast_id) == temporal_layers_.end());
	RTC_DCHECK(layers);
	temporal_layers_[simulcast_id] = layers;
	}

	BitrateAllocation SimulcastRateAllocator::GetAllocation(
	uint32_t total_bitrate_bps,
	uint32_t framerate) {
	BitrateAllocation allocated_bitrates_bps;
	DistributeAllocationToSimulcastLayers(total_bitrate_bps,
	&allocated_bitrates_bps);
	DistributeAllocationToTemporalLayers(framerate, &allocated_bitrates_bps);
	return allocated_bitrates_bps;
	}

	void SimulcastRateAllocator::DistributeAllocationToSimulcastLayers(
	uint32_t total_bitrate_bps,
	BitrateAllocation* allocated_bitrates_bps) {
	uint32_t left_to_allocate = total_bitrate_bps;
	if (codec_.maxBitrate && codec_.maxBitrate * 1000 < left_to_allocate)
	left_to_allocate = codec_.maxBitrate * 1000;

	if (codec_.numberOfSimulcastStreams == 0) {
	// No simulcast, just set the target as this has been capped already.
	if (codec_.active) {
	allocated_bitrates_bps->SetBitrate(
	0, 0, std::max(codec_.minBitrate * 1000, left_to_allocate));
	}
	return;
	}
	// Find the first active layer. We don't allocate to inactive layers.
	size_t active_layer = 0;
	for (; active_layer < codec_.numberOfSimulcastStreams; ++active_layer) {
	if (codec_.simulcastStream[active_layer].active) {
	// Found the first active layer.
	break;
	}
	}
	// All streams could be inactive, and nothing more to do.
	if (active_layer == codec_.numberOfSimulcastStreams) {
	return;
	}

	// Always allocate enough bitrate for the minimum bitrate of the first
	// active layer. Suspending below min bitrate is controlled outside the
	// codec implementation and is not overridden by this.
	left_to_allocate = std::max(
	codec_.simulcastStream[active_layer].minBitrate * 1000, left_to_allocate);

	// Begin by allocating bitrate to simulcast streams, putting all bitrate in
	// temporal layer 0. We'll then distribute this bitrate, across potential
	// temporal layers, when stream allocation is done.

	size_t top_active_layer = active_layer;
	// Allocate up to the target bitrate for each active simulcast layer.
	for (; active_layer < codec_.numberOfSimulcastStreams; ++active_layer) {
	const SimulcastStream& stream = codec_.simulcastStream[active_layer];
	if (!stream.active) {
	continue;
	}
	// If we can't allocate to the current layer we can't allocate to higher
	// layers because they require a higher minimum bitrate.
	if (left_to_allocate < stream.minBitrate * 1000) {
	break;
	}
	// We are allocating to this layer so it is the current active allocation.
	top_active_layer = active_layer;
	uint32_t allocation =
	std::min(left_to_allocate, stream.targetBitrate * 1000);
	allocated_bitrates_bps->SetBitrate(active_layer, 0, allocation);
	RTC_DCHECK_LE(allocation, left_to_allocate);
	left_to_allocate -= allocation;
	}

	// Next, try allocate remaining bitrate, up to max bitrate, in top active
	// stream.
	// TODO(sprang): Allocate up to max bitrate for all layers once we have a
	// better idea of possible performance implications.
	if (left_to_allocate > 0) {
	const SimulcastStream& stream = codec_.simulcastStream[top_active_layer];
	uint32_t bitrate_bps =
	allocated_bitrates_bps->GetSpatialLayerSum(top_active_layer);
	uint32_t allocation =
	std::min(left_to_allocate, stream.maxBitrate * 1000 - bitrate_bps);
	bitrate_bps += allocation;
	RTC_DCHECK_LE(allocation, left_to_allocate);
	left_to_allocate -= allocation;
	allocated_bitrates_bps->SetBitrate(top_active_layer, 0, bitrate_bps);
	}
	}

	void SimulcastRateAllocator::DistributeAllocationToTemporalLayers(
	uint32_t framerate,
	BitrateAllocation* allocated_bitrates_bps) {
	const int num_spatial_streams =
	std::max(1, static_cast<int>(codec_.numberOfSimulcastStreams));

	// Finally, distribute the bitrate for the simulcast streams across the
	// available temporal layers.
	for (int simulcast_id = 0; simulcast_id < num_spatial_streams;
	++simulcast_id) {
	// TODO(shampson): Consider adding a continue here if the simulcast stream
	// is inactive. Currently this is not added because the call
	// below to OnRatesUpdated changes the TemporalLayer's
	// state.
	auto tl_it = temporal_layers_.find(simulcast_id);
	if (tl_it == temporal_layers_.end())
	continue; // TODO(sprang): If > 1 SS, assume default TL alloc?

	uint32_t target_bitrate_kbps =
	allocated_bitrates_bps->GetBitrate(simulcast_id, 0) / 1000;

	const uint32_t expected_allocated_bitrate_kbps = target_bitrate_kbps;
	RTC_DCHECK_EQ(
	target_bitrate_kbps,
	allocated_bitrates_bps->GetSpatialLayerSum(simulcast_id) / 1000);
	const int num_temporal_streams = std::max<uint8_t>(
	1, codec_.numberOfSimulcastStreams == 0
	? codec_.VP8().numberOfTemporalLayers
	: codec_.simulcastStream[simulcast_id].numberOfTemporalLayers);

	uint32_t max_bitrate_kbps;
	// Legacy temporal-layered only screenshare, or simulcast screenshare
	// with legacy mode for simulcast stream 0.
	if (codec_.mode == kScreensharing && codec_.targetBitrate > 0 &&
	((num_spatial_streams == 1 && num_temporal_streams == 2) \|\| // Legacy.
	(num_spatial_streams > 1 && simulcast_id == 0))) { // Simulcast.
	// TODO(holmer): This is a "temporary" hack for screensharing, where we
	// interpret the startBitrate as the encoder target bitrate. This is
	// to allow for a different max bitrate, so if the codec can't meet
	// the target we still allow it to overshoot up to the max before dropping
	// frames. This hack should be improved.
	int tl0_bitrate = std::min(codec_.targetBitrate, target_bitrate_kbps);
	max_bitrate_kbps = std::min(codec_.maxBitrate, target_bitrate_kbps);
	target_bitrate_kbps = tl0_bitrate;
	} else if (num_spatial_streams == 1) {
	max_bitrate_kbps = codec_.maxBitrate;
	} else {
	max_bitrate_kbps = codec_.simulcastStream[simulcast_id].maxBitrate;
	}

	std::vector<uint32_t> tl_allocation = tl_it->second->OnRatesUpdated(
	target_bitrate_kbps, max_bitrate_kbps, framerate);
	RTC_DCHECK_GT(tl_allocation.size(), 0);
	RTC_DCHECK_LE(tl_allocation.size(), num_temporal_streams);

	uint64_t tl_allocation_sum_kbps = 0;
	for (size_t tl_index = 0; tl_index < tl_allocation.size(); ++tl_index) {
	uint32_t layer_rate_kbps = tl_allocation[tl_index];
	if (layer_rate_kbps > 0) {
	allocated_bitrates_bps->SetBitrate(simulcast_id, tl_index,
	layer_rate_kbps * 1000);
	}
	tl_allocation_sum_kbps += layer_rate_kbps;
	}
	RTC_DCHECK_LE(tl_allocation_sum_kbps, expected_allocated_bitrate_kbps);
	}
	}

	uint32_t SimulcastRateAllocator::GetPreferredBitrateBps(uint32_t framerate) {
	// Create a temporary instance without temporal layers, as they may be
	// stateful, and updating the bitrate to max here can cause side effects.
	SimulcastRateAllocator temp_allocator(codec_, nullptr);
	BitrateAllocation allocation =
	temp_allocator.GetAllocation(codec_.maxBitrate * 1000, framerate);
	return allocation.get_sum_bps();
	}

	const VideoCodec& webrtc::SimulcastRateAllocator::GetCodec() const {
	return codec_;
	}

	} // namespace webrtc