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/*
* Copyright (c) 2020 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/svc/scalability_structure_l2t2_key_shift.h"
#include <utility>
#include <vector>
#include "absl/base/macros.h"
#include "api/transport/rtp/dependency_descriptor.h"
#include "rtc_base/checks.h"
#include "rtc_base/logging.h"
namespace webrtc {
namespace {
DecodeTargetIndication
Dti(int sid, int tid, const ScalableVideoController::LayerFrameConfig& config) {
if (config.IsKeyframe()) {
RTC_DCHECK_EQ(config.TemporalId(), 0);
return sid < config.SpatialId() ? DecodeTargetIndication::kNotPresent
: DecodeTargetIndication::kSwitch;
}
if (sid != config.SpatialId() || tid < config.TemporalId()) {
return DecodeTargetIndication::kNotPresent;
}
if (tid == config.TemporalId() && tid > 0) {
return DecodeTargetIndication::kDiscardable;
}
return DecodeTargetIndication::kSwitch;
}
} // namespace
constexpr int ScalabilityStructureL2T2KeyShift::kNumSpatialLayers;
constexpr int ScalabilityStructureL2T2KeyShift::kNumTemporalLayers;
ScalabilityStructureL2T2KeyShift::~ScalabilityStructureL2T2KeyShift() = default;
ScalableVideoController::StreamLayersConfig
ScalabilityStructureL2T2KeyShift::StreamConfig() const {
StreamLayersConfig result;
result.num_spatial_layers = 2;
result.num_temporal_layers = 2;
result.scaling_factor_num[0] = 1;
result.scaling_factor_den[0] = 2;
result.uses_reference_scaling = true;
return result;
}
FrameDependencyStructure ScalabilityStructureL2T2KeyShift::DependencyStructure()
const {
FrameDependencyStructure structure;
structure.num_decode_targets = 4;
structure.num_chains = 2;
structure.decode_target_protected_by_chain = {0, 0, 1, 1};
structure.templates.resize(7);
auto& templates = structure.templates;
templates[0].S(0).T(0).Dtis("SSSS").ChainDiffs({0, 0});
templates[1].S(0).T(0).Dtis("SS--").ChainDiffs({2, 1}).FrameDiffs({2});
templates[2].S(0).T(0).Dtis("SS--").ChainDiffs({4, 1}).FrameDiffs({4});
templates[3].S(0).T(1).Dtis("-D--").ChainDiffs({2, 3}).FrameDiffs({2});
templates[4].S(1).T(0).Dtis("--SS").ChainDiffs({1, 1}).FrameDiffs({1});
templates[5].S(1).T(0).Dtis("--SS").ChainDiffs({3, 4}).FrameDiffs({4});
templates[6].S(1).T(1).Dtis("---D").ChainDiffs({1, 2}).FrameDiffs({2});
return structure;
}
std::vector<ScalableVideoController::LayerFrameConfig>
ScalabilityStructureL2T2KeyShift::NextFrameConfig(bool restart) {
std::vector<LayerFrameConfig> configs;
configs.reserve(2);
if (restart) {
next_pattern_ = kKey;
}
// Buffer0 keeps latest S0T0 frame,
// Buffer1 keeps latest S1T0 frame.
switch (next_pattern_) {
case kKey:
if (DecodeTargetIsActive(/*sid=*/0, /*tid=*/0)) {
configs.emplace_back();
configs.back().S(0).T(0).Update(0).Keyframe();
}
if (DecodeTargetIsActive(/*sid=*/1, /*tid=*/0)) {
configs.emplace_back();
configs.back().S(1).T(0).Update(1);
if (DecodeTargetIsActive(/*sid=*/0, /*tid=*/0)) {
configs.back().Reference(0);
} else {
configs.back().Keyframe();
}
}
next_pattern_ = kDelta0;
break;
case kDelta0:
if (DecodeTargetIsActive(/*sid=*/0, /*tid=*/0)) {
configs.emplace_back();
configs.back().S(0).T(0).ReferenceAndUpdate(0);
}
if (DecodeTargetIsActive(/*sid=*/1, /*tid=*/1)) {
configs.emplace_back();
configs.back().S(1).T(1).Reference(1);
}
if (configs.empty() && DecodeTargetIsActive(/*sid=*/1, /*tid=*/0)) {
configs.emplace_back();
configs.back().S(1).T(0).ReferenceAndUpdate(1);
}
next_pattern_ = kDelta1;
break;
case kDelta1:
if (DecodeTargetIsActive(/*sid=*/0, /*tid=*/1)) {
configs.emplace_back();
configs.back().S(0).T(1).Reference(0);
}
if (DecodeTargetIsActive(/*sid=*/1, /*tid=*/0)) {
configs.emplace_back();
configs.back().S(1).T(0).ReferenceAndUpdate(1);
}
if (configs.empty() && DecodeTargetIsActive(/*sid=*/0, /*tid=*/0)) {
configs.emplace_back();
configs.back().S(0).T(0).ReferenceAndUpdate(0);
}
next_pattern_ = kDelta0;
break;
}
RTC_DCHECK(!configs.empty() || active_decode_targets_.none());
return configs;
}
GenericFrameInfo ScalabilityStructureL2T2KeyShift::OnEncodeDone(
const LayerFrameConfig& config) {
GenericFrameInfo frame_info;
frame_info.spatial_id = config.SpatialId();
frame_info.temporal_id = config.TemporalId();
frame_info.encoder_buffers = config.Buffers();
for (int sid = 0; sid < kNumSpatialLayers; ++sid) {
for (int tid = 0; tid < kNumTemporalLayers; ++tid) {
frame_info.decode_target_indications.push_back(Dti(sid, tid, config));
}
}
if (config.IsKeyframe()) {
frame_info.part_of_chain = {true, true};
} else if (config.TemporalId() == 0) {
frame_info.part_of_chain = {config.SpatialId() == 0,
config.SpatialId() == 1};
} else {
frame_info.part_of_chain = {false, false};
}
return frame_info;
}
void ScalabilityStructureL2T2KeyShift::OnRatesUpdated(
const VideoBitrateAllocation& bitrates) {
for (int sid = 0; sid < kNumSpatialLayers; ++sid) {
// Enable/disable spatial layers independetely.
bool active = bitrates.GetBitrate(sid, /*tid=*/0) > 0;
if (!DecodeTargetIsActive(sid, /*tid=*/0) && active) {
// Key frame is required to reenable any spatial layer.
next_pattern_ = kKey;
}
SetDecodeTargetIsActive(sid, /*tid=*/0, active);
SetDecodeTargetIsActive(sid, /*tid=*/1,
active && bitrates.GetBitrate(sid, /*tid=*/1) > 0);
}
}
} // namespace webrtc