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/* Copyright (c) 2015 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 <algorithm>
#include "webrtc/modules/video_coding/codecs/vp9/screenshare_layers.h"
#include "webrtc/base/checks.h"
namespace webrtc {
ScreenshareLayersVP9::ScreenshareLayersVP9(uint8_t num_layers)
: num_layers_(num_layers),
start_layer_(0),
last_timestamp_(0),
timestamp_initialized_(false) {
RTC_DCHECK_GT(num_layers, 0);
RTC_DCHECK_LE(num_layers, kMaxVp9NumberOfSpatialLayers);
memset(bits_used_, 0, sizeof(bits_used_));
memset(threshold_kbps_, 0, sizeof(threshold_kbps_));
}
uint8_t ScreenshareLayersVP9::GetStartLayer() const {
return start_layer_;
}
void ScreenshareLayersVP9::ConfigureBitrate(int threshold_kbps,
uint8_t layer_id) {
// The upper layer is always the layer we spill frames
// to when the bitrate becomes to high, therefore setting
// a max limit is not allowed. The top layer bitrate is
// never used either so configuring it makes no difference.
RTC_DCHECK_LT(layer_id, num_layers_ - 1);
threshold_kbps_[layer_id] = threshold_kbps;
}
void ScreenshareLayersVP9::LayerFrameEncoded(unsigned int size_bytes,
uint8_t layer_id) {
RTC_DCHECK_LT(layer_id, num_layers_);
bits_used_[layer_id] += size_bytes * 8;
}
VP9EncoderImpl::SuperFrameRefSettings
ScreenshareLayersVP9::GetSuperFrameSettings(uint32_t timestamp,
bool is_keyframe) {
VP9EncoderImpl::SuperFrameRefSettings settings;
if (!timestamp_initialized_) {
last_timestamp_ = timestamp;
timestamp_initialized_ = true;
}
float time_diff = (timestamp - last_timestamp_) / 90.f;
float total_bits_used = 0;
float total_threshold_kbps = 0;
start_layer_ = 0;
// Up to (num_layers - 1) because we only have
// (num_layers - 1) thresholds to check.
for (int layer_id = 0; layer_id < num_layers_ - 1; ++layer_id) {
bits_used_[layer_id] = std::max(
0.f, bits_used_[layer_id] - time_diff * threshold_kbps_[layer_id]);
total_bits_used += bits_used_[layer_id];
total_threshold_kbps += threshold_kbps_[layer_id];
// If this is a keyframe then there should be no
// references to any previous frames.
if (!is_keyframe) {
settings.layer[layer_id].ref_buf1 = layer_id;
if (total_bits_used > total_threshold_kbps * 1000)
start_layer_ = layer_id + 1;
}
settings.layer[layer_id].upd_buf = layer_id;
}
// Since the above loop does not iterate over the last layer
// the reference of the last layer has to be set after the loop,
// and if this is a keyframe there should be no references to
// any previous frames.
if (!is_keyframe)
settings.layer[num_layers_ - 1].ref_buf1 = num_layers_ - 1;
settings.layer[num_layers_ - 1].upd_buf = num_layers_ - 1;
settings.is_keyframe = is_keyframe;
settings.start_layer = start_layer_;
settings.stop_layer = num_layers_ - 1;
last_timestamp_ = timestamp;
return settings;
}
} // namespace webrtc
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