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/*
* Copyright (c) 2022 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_mode_util.h"
#include <array>
#include <cstddef>
#include <optional>
#include <type_traits>
#include "absl/algorithm/container.h"
#include "absl/strings/string_view.h"
#include "api/video_codecs/scalability_mode.h"
#include "api/video_codecs/video_codec.h"
#include "rtc_base/checks.h"
namespace webrtc {
namespace {
struct ScalabilityModeParameters {
const ScalabilityMode scalability_mode;
const absl::string_view name;
const int num_spatial_layers;
const int num_temporal_layers;
const InterLayerPredMode inter_layer_pred;
const std::optional<ScalabilityModeResolutionRatio> ratio =
ScalabilityModeResolutionRatio::kTwoToOne;
const bool shift = false;
};
constexpr size_t kNumScalabilityModes =
static_cast<size_t>(ScalabilityMode::kS3T3h) + 1;
constexpr ScalabilityModeParameters kScalabilityModeParams[] = {
ScalabilityModeParameters{.scalability_mode = ScalabilityMode::kL1T1,
.name = "L1T1",
.num_spatial_layers = 1,
.num_temporal_layers = 1,
.inter_layer_pred = InterLayerPredMode::kOff,
.ratio = std::nullopt},
ScalabilityModeParameters{.scalability_mode = ScalabilityMode::kL1T2,
.name = "L1T2",
.num_spatial_layers = 1,
.num_temporal_layers = 2,
.inter_layer_pred = InterLayerPredMode::kOff,
.ratio = std::nullopt},
ScalabilityModeParameters{.scalability_mode = ScalabilityMode::kL1T3,
.name = "L1T3",
.num_spatial_layers = 1,
.num_temporal_layers = 3,
.inter_layer_pred = InterLayerPredMode::kOff,
.ratio = std::nullopt},
ScalabilityModeParameters{
.scalability_mode = ScalabilityMode::kL2T1,
.name = "L2T1",
.num_spatial_layers = 2,
.num_temporal_layers = 1,
.inter_layer_pred = InterLayerPredMode::kOn,
},
ScalabilityModeParameters{
.scalability_mode = ScalabilityMode::kL2T1h,
.name = "L2T1h",
.num_spatial_layers = 2,
.num_temporal_layers = 1,
.inter_layer_pred = InterLayerPredMode::kOn,
.ratio = ScalabilityModeResolutionRatio::kThreeToTwo,
},
ScalabilityModeParameters{
.scalability_mode = ScalabilityMode::kL2T1_KEY,
.name = "L2T1_KEY",
.num_spatial_layers = 2,
.num_temporal_layers = 1,
.inter_layer_pred = InterLayerPredMode::kOnKeyPic,
},
ScalabilityModeParameters{
.scalability_mode = ScalabilityMode::kL2T2,
.name = "L2T2",
.num_spatial_layers = 2,
.num_temporal_layers = 2,
.inter_layer_pred = InterLayerPredMode::kOn,
},
ScalabilityModeParameters{
.scalability_mode = ScalabilityMode::kL2T2h,
.name = "L2T2h",
.num_spatial_layers = 2,
.num_temporal_layers = 2,
.inter_layer_pred = InterLayerPredMode::kOn,
.ratio = ScalabilityModeResolutionRatio::kThreeToTwo,
},
ScalabilityModeParameters{
.scalability_mode = ScalabilityMode::kL2T2_KEY,
.name = "L2T2_KEY",
.num_spatial_layers = 2,
.num_temporal_layers = 2,
.inter_layer_pred = InterLayerPredMode::kOnKeyPic,
},
ScalabilityModeParameters{
.scalability_mode = ScalabilityMode::kL2T2_KEY_SHIFT,
.name = "L2T2_KEY_SHIFT",
.num_spatial_layers = 2,
.num_temporal_layers = 2,
.inter_layer_pred = InterLayerPredMode::kOnKeyPic,
.shift = true},
ScalabilityModeParameters{
.scalability_mode = ScalabilityMode::kL2T3,
.name = "L2T3",
.num_spatial_layers = 2,
.num_temporal_layers = 3,
.inter_layer_pred = InterLayerPredMode::kOn,
},
ScalabilityModeParameters{
.scalability_mode = ScalabilityMode::kL2T3h,
.name = "L2T3h",
.num_spatial_layers = 2,
.num_temporal_layers = 3,
.inter_layer_pred = InterLayerPredMode::kOn,
.ratio = ScalabilityModeResolutionRatio::kThreeToTwo,
},
ScalabilityModeParameters{
.scalability_mode = ScalabilityMode::kL2T3_KEY,
.name = "L2T3_KEY",
.num_spatial_layers = 2,
.num_temporal_layers = 3,
.inter_layer_pred = InterLayerPredMode::kOnKeyPic,
},
ScalabilityModeParameters{
.scalability_mode = ScalabilityMode::kL3T1,
.name = "L3T1",
.num_spatial_layers = 3,
.num_temporal_layers = 1,
.inter_layer_pred = InterLayerPredMode::kOn,
},
ScalabilityModeParameters{
.scalability_mode = ScalabilityMode::kL3T1h,
.name = "L3T1h",
.num_spatial_layers = 3,
.num_temporal_layers = 1,
.inter_layer_pred = InterLayerPredMode::kOn,
.ratio = ScalabilityModeResolutionRatio::kThreeToTwo,
},
ScalabilityModeParameters{
.scalability_mode = ScalabilityMode::kL3T1_KEY,
.name = "L3T1_KEY",
.num_spatial_layers = 3,
.num_temporal_layers = 1,
.inter_layer_pred = InterLayerPredMode::kOnKeyPic,
},
ScalabilityModeParameters{
.scalability_mode = ScalabilityMode::kL3T2,
.name = "L3T2",
.num_spatial_layers = 3,
.num_temporal_layers = 2,
.inter_layer_pred = InterLayerPredMode::kOn,
},
ScalabilityModeParameters{
.scalability_mode = ScalabilityMode::kL3T2h,
.name = "L3T2h",
.num_spatial_layers = 3,
.num_temporal_layers = 2,
.inter_layer_pred = InterLayerPredMode::kOn,
.ratio = ScalabilityModeResolutionRatio::kThreeToTwo,
},
ScalabilityModeParameters{
.scalability_mode = ScalabilityMode::kL3T2_KEY,
.name = "L3T2_KEY",
.num_spatial_layers = 3,
.num_temporal_layers = 2,
.inter_layer_pred = InterLayerPredMode::kOnKeyPic,
},
ScalabilityModeParameters{
.scalability_mode = ScalabilityMode::kL3T3,
.name = "L3T3",
.num_spatial_layers = 3,
.num_temporal_layers = 3,
.inter_layer_pred = InterLayerPredMode::kOn,
},
ScalabilityModeParameters{
.scalability_mode = ScalabilityMode::kL3T3h,
.name = "L3T3h",
.num_spatial_layers = 3,
.num_temporal_layers = 3,
.inter_layer_pred = InterLayerPredMode::kOn,
.ratio = ScalabilityModeResolutionRatio::kThreeToTwo,
},
ScalabilityModeParameters{
.scalability_mode = ScalabilityMode::kL3T3_KEY,
.name = "L3T3_KEY",
.num_spatial_layers = 3,
.num_temporal_layers = 3,
.inter_layer_pred = InterLayerPredMode::kOnKeyPic,
},
ScalabilityModeParameters{
.scalability_mode = ScalabilityMode::kS2T1,
.name = "S2T1",
.num_spatial_layers = 2,
.num_temporal_layers = 1,
.inter_layer_pred = InterLayerPredMode::kOff,
},
ScalabilityModeParameters{
.scalability_mode = ScalabilityMode::kS2T1h,
.name = "S2T1h",
.num_spatial_layers = 2,
.num_temporal_layers = 1,
.inter_layer_pred = InterLayerPredMode::kOff,
.ratio = ScalabilityModeResolutionRatio::kThreeToTwo,
},
ScalabilityModeParameters{
.scalability_mode = ScalabilityMode::kS2T2,
.name = "S2T2",
.num_spatial_layers = 2,
.num_temporal_layers = 2,
.inter_layer_pred = InterLayerPredMode::kOff,
},
ScalabilityModeParameters{
.scalability_mode = ScalabilityMode::kS2T2h,
.name = "S2T2h",
.num_spatial_layers = 2,
.num_temporal_layers = 2,
.inter_layer_pred = InterLayerPredMode::kOff,
.ratio = ScalabilityModeResolutionRatio::kThreeToTwo,
},
ScalabilityModeParameters{
.scalability_mode = ScalabilityMode::kS2T3,
.name = "S2T3",
.num_spatial_layers = 2,
.num_temporal_layers = 3,
.inter_layer_pred = InterLayerPredMode::kOff,
},
ScalabilityModeParameters{
.scalability_mode = ScalabilityMode::kS2T3h,
.name = "S2T3h",
.num_spatial_layers = 2,
.num_temporal_layers = 3,
.inter_layer_pred = InterLayerPredMode::kOff,
.ratio = ScalabilityModeResolutionRatio::kThreeToTwo,
},
ScalabilityModeParameters{
.scalability_mode = ScalabilityMode::kS3T1,
.name = "S3T1",
.num_spatial_layers = 3,
.num_temporal_layers = 1,
.inter_layer_pred = InterLayerPredMode::kOff,
},
ScalabilityModeParameters{
.scalability_mode = ScalabilityMode::kS3T1h,
.name = "S3T1h",
.num_spatial_layers = 3,
.num_temporal_layers = 1,
.inter_layer_pred = InterLayerPredMode::kOff,
.ratio = ScalabilityModeResolutionRatio::kThreeToTwo,
},
ScalabilityModeParameters{
.scalability_mode = ScalabilityMode::kS3T2,
.name = "S3T2",
.num_spatial_layers = 3,
.num_temporal_layers = 2,
.inter_layer_pred = InterLayerPredMode::kOff,
},
ScalabilityModeParameters{
.scalability_mode = ScalabilityMode::kS3T2h,
.name = "S3T2h",
.num_spatial_layers = 3,
.num_temporal_layers = 2,
.inter_layer_pred = InterLayerPredMode::kOff,
.ratio = ScalabilityModeResolutionRatio::kThreeToTwo,
},
ScalabilityModeParameters{
.scalability_mode = ScalabilityMode::kS3T3,
.name = "S3T3",
.num_spatial_layers = 3,
.num_temporal_layers = 3,
.inter_layer_pred = InterLayerPredMode::kOff,
},
ScalabilityModeParameters{
.scalability_mode = ScalabilityMode::kS3T3h,
.name = "S3T3h",
.num_spatial_layers = 3,
.num_temporal_layers = 3,
.inter_layer_pred = InterLayerPredMode::kOff,
.ratio = ScalabilityModeResolutionRatio::kThreeToTwo,
},
};
// This could be replaced with std::all_of in c++20.
constexpr bool CheckScalabilityModeParams() {
static_assert(std::size(kScalabilityModeParams) == kNumScalabilityModes);
for (size_t s = 0; s < kNumScalabilityModes; ++s) {
if (kScalabilityModeParams[s].scalability_mode !=
static_cast<ScalabilityMode>(s)) {
return false;
}
}
return true;
}
static_assert(CheckScalabilityModeParams(),
"There is a scalability mode mismatch in the array!");
constexpr auto Idx(ScalabilityMode s) {
const auto index = static_cast<std::underlying_type_t<ScalabilityMode>>(s);
RTC_CHECK_LT(index, kNumScalabilityModes);
return index;
}
} // namespace
std::optional<ScalabilityMode> MakeScalabilityMode(
int num_spatial_layers,
int num_temporal_layers,
InterLayerPredMode inter_layer_pred,
std::optional<ScalabilityModeResolutionRatio> ratio,
bool shift) {
for (const auto& candidate_mode : kScalabilityModeParams) {
if (candidate_mode.num_spatial_layers == num_spatial_layers &&
candidate_mode.num_temporal_layers == num_temporal_layers) {
if (num_spatial_layers == 1 ||
(candidate_mode.inter_layer_pred == inter_layer_pred &&
candidate_mode.ratio == ratio && candidate_mode.shift == shift)) {
return candidate_mode.scalability_mode;
}
}
}
return std::nullopt;
}
std::optional<ScalabilityMode> ScalabilityModeFromString(
absl::string_view mode_string) {
const auto it =
absl::c_find_if(kScalabilityModeParams,
[&](const ScalabilityModeParameters& candidate_mode) {
return candidate_mode.name == mode_string;
});
if (it != std::end(kScalabilityModeParams)) {
return it->scalability_mode;
}
return std::nullopt;
}
InterLayerPredMode ScalabilityModeToInterLayerPredMode(
ScalabilityMode scalability_mode) {
return kScalabilityModeParams[Idx(scalability_mode)].inter_layer_pred;
}
int ScalabilityModeToNumSpatialLayers(ScalabilityMode scalability_mode) {
return kScalabilityModeParams[Idx(scalability_mode)].num_spatial_layers;
}
int ScalabilityModeToNumTemporalLayers(ScalabilityMode scalability_mode) {
return kScalabilityModeParams[Idx(scalability_mode)].num_temporal_layers;
}
std::optional<ScalabilityModeResolutionRatio> ScalabilityModeToResolutionRatio(
ScalabilityMode scalability_mode) {
return kScalabilityModeParams[Idx(scalability_mode)].ratio;
}
ScalabilityMode LimitNumSpatialLayers(ScalabilityMode scalability_mode,
int max_spatial_layers) {
int num_spatial_layers = ScalabilityModeToNumSpatialLayers(scalability_mode);
if (max_spatial_layers >= num_spatial_layers) {
return scalability_mode;
}
switch (scalability_mode) {
case ScalabilityMode::kL1T1:
return ScalabilityMode::kL1T1;
case ScalabilityMode::kL1T2:
return ScalabilityMode::kL1T2;
case ScalabilityMode::kL1T3:
return ScalabilityMode::kL1T3;
case ScalabilityMode::kL2T1:
return ScalabilityMode::kL1T1;
case ScalabilityMode::kL2T1h:
return ScalabilityMode::kL1T1;
case ScalabilityMode::kL2T1_KEY:
return ScalabilityMode::kL1T1;
case ScalabilityMode::kL2T2:
return ScalabilityMode::kL1T2;
case ScalabilityMode::kL2T2h:
return ScalabilityMode::kL1T2;
case ScalabilityMode::kL2T2_KEY:
return ScalabilityMode::kL1T2;
case ScalabilityMode::kL2T2_KEY_SHIFT:
return ScalabilityMode::kL1T2;
case ScalabilityMode::kL2T3:
return ScalabilityMode::kL1T3;
case ScalabilityMode::kL2T3h:
return ScalabilityMode::kL1T3;
case ScalabilityMode::kL2T3_KEY:
return ScalabilityMode::kL1T3;
case ScalabilityMode::kL3T1:
return max_spatial_layers == 2 ? ScalabilityMode::kL2T1
: ScalabilityMode::kL1T1;
case ScalabilityMode::kL3T1h:
return max_spatial_layers == 2 ? ScalabilityMode::kL2T1h
: ScalabilityMode::kL1T1;
case ScalabilityMode::kL3T1_KEY:
return max_spatial_layers == 2 ? ScalabilityMode::kL2T1_KEY
: ScalabilityMode::kL1T1;
case ScalabilityMode::kL3T2:
return max_spatial_layers == 2 ? ScalabilityMode::kL2T2
: ScalabilityMode::kL1T2;
case ScalabilityMode::kL3T2h:
return max_spatial_layers == 2 ? ScalabilityMode::kL2T2h
: ScalabilityMode::kL1T2;
case ScalabilityMode::kL3T2_KEY:
return max_spatial_layers == 2 ? ScalabilityMode::kL2T2_KEY
: ScalabilityMode::kL1T2;
case ScalabilityMode::kL3T3:
return max_spatial_layers == 2 ? ScalabilityMode::kL2T3
: ScalabilityMode::kL1T3;
case ScalabilityMode::kL3T3h:
return max_spatial_layers == 2 ? ScalabilityMode::kL2T3h
: ScalabilityMode::kL1T3;
case ScalabilityMode::kL3T3_KEY:
return max_spatial_layers == 2 ? ScalabilityMode::kL2T3_KEY
: ScalabilityMode::kL1T3;
case ScalabilityMode::kS2T1:
return ScalabilityMode::kL1T1;
case ScalabilityMode::kS2T1h:
return ScalabilityMode::kL1T1;
case ScalabilityMode::kS2T2:
return ScalabilityMode::kL1T2;
case ScalabilityMode::kS2T2h:
return ScalabilityMode::kL1T2;
case ScalabilityMode::kS2T3:
return ScalabilityMode::kL1T3;
case ScalabilityMode::kS2T3h:
return ScalabilityMode::kL1T3;
case ScalabilityMode::kS3T1:
return max_spatial_layers == 2 ? ScalabilityMode::kS2T1
: ScalabilityMode::kL1T1;
case ScalabilityMode::kS3T1h:
return max_spatial_layers == 2 ? ScalabilityMode::kS2T1h
: ScalabilityMode::kL1T1;
case ScalabilityMode::kS3T2:
return max_spatial_layers == 2 ? ScalabilityMode::kS2T2
: ScalabilityMode::kL1T2;
case ScalabilityMode::kS3T2h:
return max_spatial_layers == 2 ? ScalabilityMode::kS2T2h
: ScalabilityMode::kL1T2;
case ScalabilityMode::kS3T3:
return max_spatial_layers == 2 ? ScalabilityMode::kS2T3
: ScalabilityMode::kL1T3;
case ScalabilityMode::kS3T3h:
return max_spatial_layers == 2 ? ScalabilityMode::kS2T3h
: ScalabilityMode::kL1T3;
}
RTC_CHECK_NOTREACHED();
}
bool ScalabilityModeIsShiftMode(ScalabilityMode scalability_mode) {
return kScalabilityModeParams[Idx(scalability_mode)].shift;
}
} // namespace webrtc