1 /* Copyright (c) 2015 The WebRTC project authors. All Rights Reserved.
2 *
3 * Use of this source code is governed by a BSD-style license
4 * that can be found in the LICENSE file in the root of the source
5 * tree. An additional intellectual property rights grant can be found
6 * in the file PATENTS. All contributing project authors may
7 * be found in the AUTHORS file in the root of the source tree.
8 */
9
10 #include <algorithm>
11 #include "webrtc/modules/video_coding/codecs/vp9/screenshare_layers.h"
12 #include "webrtc/base/checks.h"
13
14 namespace webrtc {
15
ScreenshareLayersVP9(uint8_t num_layers)16 ScreenshareLayersVP9::ScreenshareLayersVP9(uint8_t num_layers)
17 : num_layers_(num_layers),
18 start_layer_(0),
19 last_timestamp_(0),
20 timestamp_initialized_(false) {
21 RTC_DCHECK_GT(num_layers, 0);
22 RTC_DCHECK_LE(num_layers, kMaxVp9NumberOfSpatialLayers);
23 memset(bits_used_, 0, sizeof(bits_used_));
24 memset(threshold_kbps_, 0, sizeof(threshold_kbps_));
25 }
26
GetStartLayer() const27 uint8_t ScreenshareLayersVP9::GetStartLayer() const {
28 return start_layer_;
29 }
30
ConfigureBitrate(int threshold_kbps,uint8_t layer_id)31 void ScreenshareLayersVP9::ConfigureBitrate(int threshold_kbps,
32 uint8_t layer_id) {
33 // The upper layer is always the layer we spill frames
34 // to when the bitrate becomes to high, therefore setting
35 // a max limit is not allowed. The top layer bitrate is
36 // never used either so configuring it makes no difference.
37 RTC_DCHECK_LT(layer_id, num_layers_ - 1);
38 threshold_kbps_[layer_id] = threshold_kbps;
39 }
40
LayerFrameEncoded(unsigned int size_bytes,uint8_t layer_id)41 void ScreenshareLayersVP9::LayerFrameEncoded(unsigned int size_bytes,
42 uint8_t layer_id) {
43 RTC_DCHECK_LT(layer_id, num_layers_);
44 bits_used_[layer_id] += size_bytes * 8;
45 }
46
47 VP9EncoderImpl::SuperFrameRefSettings
GetSuperFrameSettings(uint32_t timestamp,bool is_keyframe)48 ScreenshareLayersVP9::GetSuperFrameSettings(uint32_t timestamp,
49 bool is_keyframe) {
50 VP9EncoderImpl::SuperFrameRefSettings settings;
51 if (!timestamp_initialized_) {
52 last_timestamp_ = timestamp;
53 timestamp_initialized_ = true;
54 }
55 float time_diff = (timestamp - last_timestamp_) / 90.f;
56 float total_bits_used = 0;
57 float total_threshold_kbps = 0;
58 start_layer_ = 0;
59
60 // Up to (num_layers - 1) because we only have
61 // (num_layers - 1) thresholds to check.
62 for (int layer_id = 0; layer_id < num_layers_ - 1; ++layer_id) {
63 bits_used_[layer_id] = std::max(
64 0.f, bits_used_[layer_id] - time_diff * threshold_kbps_[layer_id]);
65 total_bits_used += bits_used_[layer_id];
66 total_threshold_kbps += threshold_kbps_[layer_id];
67
68 // If this is a keyframe then there should be no
69 // references to any previous frames.
70 if (!is_keyframe) {
71 settings.layer[layer_id].ref_buf1 = layer_id;
72 if (total_bits_used > total_threshold_kbps * 1000)
73 start_layer_ = layer_id + 1;
74 }
75
76 settings.layer[layer_id].upd_buf = layer_id;
77 }
78 // Since the above loop does not iterate over the last layer
79 // the reference of the last layer has to be set after the loop,
80 // and if this is a keyframe there should be no references to
81 // any previous frames.
82 if (!is_keyframe)
83 settings.layer[num_layers_ - 1].ref_buf1 = num_layers_ - 1;
84
85 settings.layer[num_layers_ - 1].upd_buf = num_layers_ - 1;
86 settings.is_keyframe = is_keyframe;
87 settings.start_layer = start_layer_;
88 settings.stop_layer = num_layers_ - 1;
89 last_timestamp_ = timestamp;
90 return settings;
91 }
92
93 } // namespace webrtc
94