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Add max pre-decode queue size threshold for pacing

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When pacing is enabled for the low latency rendering path,
frames are sent to the decoder in regular intervals. In case of a
jitter, these frames intervals could add up to create a large latency.
Hence, disable frame pacing if the pre-decode queue grows beyond the
threshold. The threshold for when to disable frame pacing is set
through a field trial. The default value is high enough so that
the behavior is not changed unless the field trial is specified.

Bug: chromium:1237402
Change-Id: I901fd579f68da286eca3d654118f60d3c55e21ce
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/228241
Reviewed-by: Ilya Nikolaevskiy <ilnik@webrtc.org>
Commit-Queue: Johannes Kron <kron@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#34705}
This commit is contained in:
Johannes Kron
2021-08-10 16:56:12 +02:00
committed by WebRTC LUCI CQ
parent 5653c95ca2
commit 2ddc39e2b9
7 changed files with 119 additions and 28 deletions
Download Patch File Download Diff File Expand all files Collapse all files

99
modules/video_coding/timing_unittest.cc
View File

@ -36,7 +36,7 @@ TEST(ReceiverTimingTest, JitterDelay) {
timing.set_render_delay(0);
uint32_t wait_time_ms = timing.MaxWaitingTime(
timing.RenderTimeMs(timestamp, clock.TimeInMilliseconds()),
clock.TimeInMilliseconds());
clock.TimeInMilliseconds(), /*too_many_frames_queued=*/false);
// First update initializes the render time. Since we have no decode delay
// we get wait_time_ms = renderTime - now - renderDelay = jitter.
EXPECT_EQ(jitter_delay_ms, wait_time_ms);
@ -48,7 +48,7 @@ TEST(ReceiverTimingTest, JitterDelay) {
timing.UpdateCurrentDelay(timestamp);
wait_time_ms = timing.MaxWaitingTime(
timing.RenderTimeMs(timestamp, clock.TimeInMilliseconds()),
clock.TimeInMilliseconds());
clock.TimeInMilliseconds(), /*too_many_frames_queued=*/false);
// Since we gradually increase the delay we only get 100 ms every second.
EXPECT_EQ(jitter_delay_ms - 10, wait_time_ms);
@ -57,7 +57,7 @@ TEST(ReceiverTimingTest, JitterDelay) {
timing.UpdateCurrentDelay(timestamp);
wait_time_ms = timing.MaxWaitingTime(
timing.RenderTimeMs(timestamp, clock.TimeInMilliseconds()),
clock.TimeInMilliseconds());
clock.TimeInMilliseconds(), /*too_many_frames_queued=*/false);
EXPECT_EQ(jitter_delay_ms, wait_time_ms);
// Insert frames without jitter, verify that this gives the exact wait time.
@ -70,7 +70,7 @@ TEST(ReceiverTimingTest, JitterDelay) {
timing.UpdateCurrentDelay(timestamp);
wait_time_ms = timing.MaxWaitingTime(
timing.RenderTimeMs(timestamp, clock.TimeInMilliseconds()),
clock.TimeInMilliseconds());
clock.TimeInMilliseconds(), /*too_many_frames_queued=*/false);
EXPECT_EQ(jitter_delay_ms, wait_time_ms);
// Add decode time estimates for 1 second.
@ -85,7 +85,7 @@ TEST(ReceiverTimingTest, JitterDelay) {
timing.UpdateCurrentDelay(timestamp);
wait_time_ms = timing.MaxWaitingTime(
timing.RenderTimeMs(timestamp, clock.TimeInMilliseconds()),
clock.TimeInMilliseconds());
clock.TimeInMilliseconds(), /*too_many_frames_queued=*/false);
EXPECT_EQ(jitter_delay_ms, wait_time_ms);
const int kMinTotalDelayMs = 200;
@ -97,7 +97,7 @@ TEST(ReceiverTimingTest, JitterDelay) {
timing.set_render_delay(kRenderDelayMs);
wait_time_ms = timing.MaxWaitingTime(
timing.RenderTimeMs(timestamp, clock.TimeInMilliseconds()),
clock.TimeInMilliseconds());
clock.TimeInMilliseconds(), /*too_many_frames_queued=*/false);
// We should at least have kMinTotalDelayMs - decodeTime (10) - renderTime
// (10) to wait.
EXPECT_EQ(kMinTotalDelayMs - kDecodeTimeMs - kRenderDelayMs, wait_time_ms);
@ -140,16 +140,26 @@ TEST(ReceiverTimingTest, MaxWaitingTimeIsZeroForZeroRenderTime) {
for (int i = 0; i < 10; ++i) {
clock.AdvanceTimeMilliseconds(kTimeDeltaMs);
int64_t now_ms = clock.TimeInMilliseconds();
EXPECT_LT(timing.MaxWaitingTime(kZeroRenderTimeMs, now_ms), 0);
EXPECT_LT(timing.MaxWaitingTime(kZeroRenderTimeMs, now_ms,
/*too_many_frames_queued=*/false),
0);
}
// Another frame submitted at the same time also returns a negative max
// waiting time.
int64_t now_ms = clock.TimeInMilliseconds();
EXPECT_LT(timing.MaxWaitingTime(kZeroRenderTimeMs, now_ms), 0);
EXPECT_LT(timing.MaxWaitingTime(kZeroRenderTimeMs, now_ms,
/*too_many_frames_queued=*/false),
0);
// MaxWaitingTime should be less than zero even if there's a burst of frames.
EXPECT_LT(timing.MaxWaitingTime(kZeroRenderTimeMs, now_ms), 0);
EXPECT_LT(timing.MaxWaitingTime(kZeroRenderTimeMs, now_ms), 0);
EXPECT_LT(timing.MaxWaitingTime(kZeroRenderTimeMs, now_ms), 0);
EXPECT_LT(timing.MaxWaitingTime(kZeroRenderTimeMs, now_ms,
/*too_many_frames_queued=*/false),
0);
EXPECT_LT(timing.MaxWaitingTime(kZeroRenderTimeMs, now_ms,
/*too_many_frames_queued=*/false),
0);
EXPECT_LT(timing.MaxWaitingTime(kZeroRenderTimeMs, now_ms,
/*too_many_frames_queued=*/false),
0);
}
TEST(ReceiverTimingTest, MaxWaitingTimeZeroDelayPacingExperiment) {
@ -168,27 +178,38 @@ TEST(ReceiverTimingTest, MaxWaitingTimeZeroDelayPacingExperiment) {
for (int i = 0; i < 10; ++i) {
clock.AdvanceTimeMilliseconds(kTimeDeltaMs);
int64_t now_ms = clock.TimeInMilliseconds();
EXPECT_EQ(timing.MaxWaitingTime(kZeroRenderTimeMs, now_ms), 0);
EXPECT_EQ(timing.MaxWaitingTime(kZeroRenderTimeMs, now_ms,
/*too_many_frames_queued=*/false),
0);
timing.SetLastDecodeScheduledTimestamp(now_ms);
}
// Another frame submitted at the same time is paced according to the field
// trial setting.
int64_t now_ms = clock.TimeInMilliseconds();
EXPECT_EQ(timing.MaxWaitingTime(kZeroRenderTimeMs, now_ms), kMinPacingMs);
EXPECT_EQ(timing.MaxWaitingTime(kZeroRenderTimeMs, now_ms,
/*too_many_frames_queued=*/false),
kMinPacingMs);
// If there's a burst of frames, the wait time is calculated based on next
// decode time.
EXPECT_EQ(timing.MaxWaitingTime(kZeroRenderTimeMs, now_ms), kMinPacingMs);
EXPECT_EQ(timing.MaxWaitingTime(kZeroRenderTimeMs, now_ms), kMinPacingMs);
EXPECT_EQ(timing.MaxWaitingTime(kZeroRenderTimeMs, now_ms,
/*too_many_frames_queued=*/false),
kMinPacingMs);
EXPECT_EQ(timing.MaxWaitingTime(kZeroRenderTimeMs, now_ms,
/*too_many_frames_queued=*/false),
kMinPacingMs);
// Allow a few ms to pass, this should be subtracted from the MaxWaitingTime.
constexpr int64_t kTwoMs = 2;
clock.AdvanceTimeMilliseconds(kTwoMs);
now_ms = clock.TimeInMilliseconds();
EXPECT_EQ(timing.MaxWaitingTime(kZeroRenderTimeMs, now_ms),
EXPECT_EQ(timing.MaxWaitingTime(kZeroRenderTimeMs, now_ms,
/*too_many_frames_queued=*/false),
kMinPacingMs - kTwoMs);
// A frame is decoded at the current time, the wait time should be restored to
// pacing delay.
timing.SetLastDecodeScheduledTimestamp(now_ms);
EXPECT_EQ(timing.MaxWaitingTime(kZeroRenderTimeMs, now_ms), kMinPacingMs);
EXPECT_EQ(timing.MaxWaitingTime(kZeroRenderTimeMs, now_ms,
/*too_many_frames_queued=*/false),
kMinPacingMs);
}
TEST(ReceiverTimingTest, DefaultMaxWaitingTimeUnaffectedByPacingExperiment) {
@ -206,16 +227,56 @@ TEST(ReceiverTimingTest, DefaultMaxWaitingTimeUnaffectedByPacingExperiment) {
int64_t render_time_ms = now_ms + 30;
// Estimate the internal processing delay from the first frame.
int64_t estimated_processing_delay =
(render_time_ms - now_ms) - timing.MaxWaitingTime(render_time_ms, now_ms);
(render_time_ms - now_ms) -
timing.MaxWaitingTime(render_time_ms, now_ms,
/*too_many_frames_queued=*/false);
EXPECT_GT(estimated_processing_delay, 0);
// Any other frame submitted at the same time should be scheduled according to
// its render time.
for (int i = 0; i < 5; ++i) {
render_time_ms += kTimeDeltaMs;
EXPECT_EQ(timing.MaxWaitingTime(render_time_ms, now_ms),
EXPECT_EQ(timing.MaxWaitingTime(render_time_ms, now_ms,
/*too_many_frames_queued=*/false),
render_time_ms - now_ms - estimated_processing_delay);
}
}
TEST(ReceiverTiminTest, MaxWaitingTimeReturnsZeroIfTooManyFramesQueuedIsTrue) {
// The minimum pacing is enabled by a field trial and active if the RTP
// playout delay header extension is set to min==0.
constexpr int64_t kMinPacingMs = 3;
test::ScopedFieldTrials override_field_trials(
"WebRTC-ZeroPlayoutDelay/min_pacing:3ms/");
constexpr int64_t kStartTimeUs = 3.15e13; // About one year in us.
constexpr int64_t kTimeDeltaMs = 1000.0 / 60.0;
constexpr int64_t kZeroRenderTimeMs = 0;
SimulatedClock clock(kStartTimeUs);
VCMTiming timing(&clock);
timing.Reset();
// MaxWaitingTime() returns zero for evenly spaced video frames.
for (int i = 0; i < 10; ++i) {
clock.AdvanceTimeMilliseconds(kTimeDeltaMs);
int64_t now_ms = clock.TimeInMilliseconds();
EXPECT_EQ(timing.MaxWaitingTime(kZeroRenderTimeMs, now_ms,
/*too_many_frames_queued=*/false),
0);
timing.SetLastDecodeScheduledTimestamp(now_ms);
}
// Another frame submitted at the same time is paced according to the field
// trial setting.
int64_t now_ms = clock.TimeInMilliseconds();
EXPECT_EQ(timing.MaxWaitingTime(kZeroRenderTimeMs, now_ms,
/*too_many_frames_queued=*/false),
kMinPacingMs);
// MaxWaitingTime returns 0 even if there's a burst of frames if
// too_many_frames_queued is set to true.
EXPECT_EQ(timing.MaxWaitingTime(kZeroRenderTimeMs, now_ms,
/*too_many_frames_queued=*/true),
0);
EXPECT_EQ(timing.MaxWaitingTime(kZeroRenderTimeMs, now_ms,
/*too_many_frames_queued=*/true),
0);
}
} // namespace webrtc