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Update screen simulcast config

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Lower then bitrate so that the delta between the highest layer of the
lower stream and lowest layer of the higher stream is not too large.

BUG=webrtc:4172

This is a reland of the following CL:

Review-Url: https://codereview.webrtc.org/2791273002
Cr-Commit-Position: refs/heads/master@{#18232}
Committed: dceb42da3e

https: //codereview.webrtc.org/2883963002
Review-Url: https://codereview.webrtc.org/2966833002
Cr-Commit-Position: refs/heads/master@{#18913}
This commit is contained in:
sprang 2017-07-06 05:05:50 -07:00 committed by Commit Bot
parent 168794c43c
commit 02569adfd4
1 changed files with 66 additions and 36 deletions
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102
webrtc/media/engine/simulcast.cc
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@ -49,7 +49,7 @@ const SimulcastFormat kSimulcastFormats[] = {
{0, 0, 1, 200, 150, 30}
};
const int kDefaultScreenshareSimulcastStreams = 2;
const int kMaxScreenshareSimulcastStreams = 2;
// Multiway: Number of temporal layers for each simulcast stream, for maximum
// possible number of simulcast streams |kMaxSimulcastStreams|. The array
@ -176,8 +176,12 @@ std::vector<webrtc::VideoStream> GetSimulcastConfig(size_t max_streams,
bool is_screencast) {
size_t num_simulcast_layers;
if (is_screencast) {
num_simulcast_layers =
UseSimulcastScreenshare() ? kDefaultScreenshareSimulcastStreams : 1;
if (UseSimulcastScreenshare()) {
num_simulcast_layers =
std::min<int>(max_streams, kMaxScreenshareSimulcastStreams);
} else {
num_simulcast_layers = 1;
}
} else {
num_simulcast_layers = FindSimulcastMaxLayers(width, height);
}
@ -194,33 +198,60 @@ std::vector<webrtc::VideoStream> GetSimulcastConfig(size_t max_streams,
std::vector<webrtc::VideoStream> streams;
streams.resize(num_simulcast_layers);
if (!is_screencast) {
if (is_screencast) {
ScreenshareLayerConfig config = ScreenshareLayerConfig::GetDefault();
// For legacy screenshare in conference mode, tl0 and tl1 bitrates are
// piggybacked on the VideoCodec struct as target and max bitrates,
// respectively. See eg. webrtc::VP8EncoderImpl::SetRates().
streams[0].width = width;
streams[0].height = height;
streams[0].max_qp = max_qp;
streams[0].max_framerate = 5;
streams[0].min_bitrate_bps = kMinVideoBitrateKbps * 1000;
streams[0].target_bitrate_bps = config.tl0_bitrate_kbps * 1000;
streams[0].max_bitrate_bps = config.tl1_bitrate_kbps * 1000;
streams[0].temporal_layer_thresholds_bps.clear();
streams[0].temporal_layer_thresholds_bps.push_back(config.tl0_bitrate_kbps *
1000);
// With simulcast enabled, add another spatial layer. This one will have a
// more normal layout, with the regular 3 temporal layer pattern and no fps
// restrictions. The base simulcast stream will still use legacy setup.
if (num_simulcast_layers == kMaxScreenshareSimulcastStreams) {
// Add optional upper simulcast layer.
// Lowest temporal layers of a 3 layer setup will have 40% of the total
// bitrate allocation for that stream. Make sure the gap between the
// target of the lower stream and first temporal layer of the higher one
// is at most 2x the bitrate, so that upswitching is not hampered by
// stalled bitrate estimates.
int max_bitrate_bps = 2 * ((streams[0].target_bitrate_bps * 10) / 4);
// Cap max bitrate so it isn't overly high for the given resolution.
max_bitrate_bps = std::min<int>(
max_bitrate_bps, FindSimulcastMaxBitrateBps(width, height));
streams[1].width = width;
streams[1].height = height;
streams[1].max_qp = max_qp;
streams[1].max_framerate = max_framerate;
// Three temporal layers means two thresholds.
streams[1].temporal_layer_thresholds_bps.resize(2);
streams[1].min_bitrate_bps = streams[0].target_bitrate_bps * 2;
streams[1].target_bitrate_bps = max_bitrate_bps;
streams[1].max_bitrate_bps = max_bitrate_bps;
}
} else {
// Format width and height has to be divisible by |2 ^ number_streams - 1|.
width = NormalizeSimulcastSize(width, num_simulcast_layers);
height = NormalizeSimulcastSize(height, num_simulcast_layers);
}
// Add simulcast sub-streams from lower resolution to higher resolutions.
// Add simulcast streams, from highest resolution (|s| = number_streams -1)
// to lowest resolution at |s| = 0.
for (size_t s = num_simulcast_layers - 1;; --s) {
streams[s].width = width;
streams[s].height = height;
// TODO(pbos): Fill actual temporal-layer bitrate thresholds.
streams[s].max_qp = max_qp;
if (is_screencast && s == 0) {
ScreenshareLayerConfig config = ScreenshareLayerConfig::GetDefault();
// For legacy screenshare in conference mode, tl0 and tl1 bitrates are
// piggybacked on the VideoCodec struct as target and max bitrates,
// respectively. See eg. webrtc::VP8EncoderImpl::SetRates().
streams[s].min_bitrate_bps = kMinVideoBitrateKbps * 1000;
streams[s].target_bitrate_bps = config.tl0_bitrate_kbps * 1000;
streams[s].max_bitrate_bps = config.tl1_bitrate_kbps * 1000;
streams[s].temporal_layer_thresholds_bps.clear();
streams[s].temporal_layer_thresholds_bps.push_back(
config.tl0_bitrate_kbps * 1000);
streams[s].max_framerate = 5;
} else {
// Add simulcast sub-streams from lower resolution to higher resolutions.
// Add simulcast streams, from highest resolution (|s| = number_streams -1)
// to lowest resolution at |s| = 0.
for (size_t s = num_simulcast_layers - 1;; --s) {
streams[s].width = width;
streams[s].height = height;
// TODO(pbos): Fill actual temporal-layer bitrate thresholds.
streams[s].max_qp = max_qp;
streams[s].temporal_layer_thresholds_bps.resize(
kDefaultConferenceNumberOfTemporalLayers[s] - 1);
streams[s].max_bitrate_bps = FindSimulcastMaxBitrateBps(width, height);
@ -228,20 +259,19 @@ std::vector<webrtc::VideoStream> GetSimulcastConfig(size_t max_streams,
FindSimulcastTargetBitrateBps(width, height);
streams[s].min_bitrate_bps = FindSimulcastMinBitrateBps(width, height);
streams[s].max_framerate = max_framerate;
}
if (!is_screencast) {
width /= 2;
height /= 2;
}
if (s == 0)
break;
}
// Spend additional bits to boost the max stream.
int bitrate_left_bps = max_bitrate_bps - GetTotalMaxBitrateBps(streams);
if (bitrate_left_bps > 0) {
streams.back().max_bitrate_bps += bitrate_left_bps;
if (s == 0)
break;
}
// Spend additional bits to boost the max stream.
int bitrate_left_bps = max_bitrate_bps - GetTotalMaxBitrateBps(streams);
if (bitrate_left_bps > 0) {
streams.back().max_bitrate_bps += bitrate_left_bps;
}
}
return streams;