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Smoother frame dropping when screenshare_layers limits fps

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Currently, when input fps is higher than the configured target fps in
screenshare_layers, we drop frames with the help of a rate tracker using
a one second sliding window. This is not optimal.
For instance, given a 5fps limit and a 30fps capturer, the window will
not be saturated until we have added the first 5 frames. Then we will
drop all frames until the oldest one drops out, at which point we can
immediately fill it's place. This results in quick 5 frame bursts every
second.

In addition to rate tracker, also set a limit on minimum interval
required between input frames, based on target frame rate.

Bug: webrtc:4172
Change-Id: I49f0abf4d549673cc6b3fafe580b529ea3feaf57
Reviewed-on: https://webrtc-review.googlesource.com/34380
Commit-Queue: Erik Språng <sprang@webrtc.org>
Reviewed-by: Ilya Nikolaevskiy <ilnik@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#21325}
This commit is contained in:
Erik Språng
2017-12-18 14:07:15 +01:00
committed by Commit Bot
parent aaedf75520
commit 28a06b16cc
2 changed files with 44 additions and 18 deletions
Download Patch File Download Diff File Expand all files Collapse all files

36
modules/video_coding/codecs/vp8/screenshare_layers_unittest.cc
View File

@ -442,7 +442,12 @@ TEST_F(ScreenshareLayerTest, RespectsMaxIntervalBetweenFrames) {
ASSERT_GT(kStartTimestamp + 90 * (kLargeFrameSizeBytes * 8) / kLowBitrateKbps,
kStartTimestamp + (ScreenshareLayers::kMaxFrameIntervalMs * 90));
EXPECT_TRUE(layers_->UpdateLayerConfig(kTwoSecondsLater).drop_frame);
// Expect drop one frame interval before the two second timeout. If we try
// any later, the frame will be dropped anyway by the frame rate throttling
// logic.
EXPECT_TRUE(layers_->UpdateLayerConfig(kTwoSecondsLater - kTimestampDelta5Fps)
.drop_frame);
// More than two seconds has passed since last frame, one should be emitted
// even if bitrate target is then exceeded.
EXPECT_EQ(kTl0Flags, VP8EncoderImpl::EncodeFlags(
@ -472,8 +477,6 @@ TEST_F(ScreenshareLayerTest, UpdatesHistograms) {
// Simulate one overshoot.
layers_->FrameEncoded(0, 0);
overshoot = true;
flags =
VP8EncoderImpl::EncodeFlags(layers_->UpdateLayerConfig(timestamp));
}
if (flags == kTl0Flags) {
@ -589,13 +592,6 @@ TEST_F(ScreenshareLayerTest, 2LayersSyncAtOvershootDrop) {
// Simulate overshoot of this frame.
layers_->FrameEncoded(0, -1);
// Reencode, frame config, flags and codec specific info should remain the
// same as for the dropped frame.
timestamp_ -= kTimestampDelta5Fps; // Undo last timestamp increment.
TemporalLayers::FrameConfig new_tl_config =
layers_->UpdateLayerConfig(timestamp_);
EXPECT_EQ(tl_config_, new_tl_config);
config_updated_ = layers_->UpdateConfiguration(&cfg_);
EXPECT_EQ(kTl1SyncFlags, VP8EncoderImpl::EncodeFlags(tl_config_));
@ -604,4 +600,24 @@ TEST_F(ScreenshareLayerTest, 2LayersSyncAtOvershootDrop) {
EXPECT_TRUE(new_vp8_info.layerSync);
}
TEST_F(ScreenshareLayerTest, DropOnTooShortFrameInterval) {
// Run grace period so we have existing frames in both TL0 and Tl1.
EXPECT_TRUE(RunGracePeriod());
// Add a large gap, so there's plenty of room in the rate tracker.
timestamp_ += kTimestampDelta5Fps * 3;
EXPECT_FALSE(layers_->UpdateLayerConfig(timestamp_).drop_frame);
layers_->FrameEncoded(frame_size_, kDefaultQp);
// Frame interval below 90% if desired time is not allowed, try inserting
// frame just before this limit.
const int64_t kMinFrameInterval = (kTimestampDelta5Fps * 9) / 10;
timestamp_ += kMinFrameInterval - 90;
EXPECT_TRUE(layers_->UpdateLayerConfig(timestamp_).drop_frame);
// Try again at the limit, now it should pass.
timestamp_ += 90;
EXPECT_FALSE(layers_->UpdateLayerConfig(timestamp_).drop_frame);
}
} // namespace webrtc