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- // Copyright (c) 2015 The Chromium Authors. All rights reserved.
- // Use of this source code is governed by a BSD-style license that can be
- // found in the LICENSE file.
- #include "media/capture/content/video_capture_oracle.h"
- #include <algorithm>
- #include <limits>
- #include <utility>
- #include "base/callback.h"
- #include "base/compiler_specific.h"
- #include "base/format_macros.h"
- #include "base/logging.h"
- #include "base/numerics/safe_conversions.h"
- #include "base/strings/stringprintf.h"
- namespace media {
- namespace {
- // When a non-compositor event arrives after animation has halted, this
- // controls how much time must elapse before deciding to allow a capture.
- constexpr auto kAnimationHaltPeriodBeforeCaptureAllowed =
- base::Milliseconds(250);
- // When estimating frame durations, this is the hard upper-bound on the
- // estimate.
- constexpr auto kUpperBoundsDurationEstimate = base::Seconds(1);
- // The half-life of data points provided to the accumulator used when evaluating
- // the recent utilization of the buffer pool. This value is based on a
- // simulation, and reacts quickly to change to avoid depleting the buffer pool
- // (which would cause hard frame drops).
- constexpr auto kBufferUtilizationEvaluationInterval = base::Milliseconds(200);
- // The half-life of data points provided to the accumulator used when evaluating
- // the recent resource utilization of the consumer. The trade-off made here is
- // reaction time versus over-reacting to outlier data points.
- constexpr auto kConsumerCapabilityEvaluationInterval = base::Seconds(1);
- // The maximum amount of time that may elapse without a feedback update. Any
- // longer, and currently-accumulated feedback is not considered recent enough to
- // base decisions off of. This prevents changes to the capture size when there
- // is an unexpected pause in events.
- constexpr auto kMaxTimeSinceLastFeedbackUpdate = base::Seconds(1);
- // The amount of additional time, since content animation was last detected, to
- // continue being extra-careful about increasing the capture size. This is used
- // to prevent breif periods of non-animating content from throwing off the
- // heuristics that decide whether to increase the capture size.
- constexpr auto kDebouncingPeriodForAnimatedContent = base::Seconds(3);
- // When content is animating, this is the length of time the system must be
- // contiguously under-utilized before increasing the capture size.
- constexpr auto kProvingPeriodForAnimatedContent = base::Seconds(30);
- // Given the amount of time between frames, compare to the expected amount of
- // time between frames at |frame_rate| and return the fractional difference.
- double FractionFromExpectedFrameRate(base::TimeDelta delta, int frame_rate) {
- DCHECK_GT(frame_rate, 0);
- const base::TimeDelta expected_delta = base::Seconds(1) / frame_rate;
- return (delta - expected_delta) / expected_delta;
- }
- // Returns the next-higher TimeTicks value.
- base::TimeTicks JustAfter(base::TimeTicks t) {
- return t + base::Microseconds(1);
- }
- } // anonymous namespace
- // static
- constexpr base::TimeDelta VideoCaptureOracle::kDefaultMinCapturePeriod;
- // static
- constexpr base::TimeDelta VideoCaptureOracle::kDefaultMinSizeChangePeriod;
- VideoCaptureOracle::VideoCaptureOracle(bool enable_auto_throttling)
- : capture_size_throttling_mode_(
- enable_auto_throttling ? kThrottlingEnabled : kThrottlingDisabled),
- min_size_change_period_(kDefaultMinSizeChangePeriod),
- next_frame_number_(0),
- last_successfully_delivered_frame_number_(-1),
- num_frames_pending_(0),
- smoothing_sampler_(kDefaultMinCapturePeriod),
- content_sampler_(kDefaultMinCapturePeriod),
- min_capture_period_(kDefaultMinCapturePeriod),
- buffer_pool_utilization_(kBufferUtilizationEvaluationInterval),
- estimated_capable_area_(kConsumerCapabilityEvaluationInterval) {
- VLOG(1) << "Capture size auto-throttling is now "
- << (enable_auto_throttling ? "enabled." : "disabled.");
- }
- VideoCaptureOracle::~VideoCaptureOracle() = default;
- void VideoCaptureOracle::SetMinCapturePeriod(base::TimeDelta period) {
- DCHECK_GT(period, base::TimeDelta());
- min_capture_period_ = period;
- smoothing_sampler_.SetMinCapturePeriod(period);
- content_sampler_.SetMinCapturePeriod(period);
- }
- void VideoCaptureOracle::SetCaptureSizeConstraints(
- const gfx::Size& min_size,
- const gfx::Size& max_size,
- bool use_fixed_aspect_ratio) {
- resolution_chooser_.SetConstraints(min_size, max_size,
- use_fixed_aspect_ratio);
- }
- void VideoCaptureOracle::SetAutoThrottlingEnabled(bool enabled) {
- const bool was_enabled =
- (capture_size_throttling_mode_ != kThrottlingDisabled);
- if (was_enabled == enabled)
- return;
- capture_size_throttling_mode_ =
- enabled ? kThrottlingEnabled : kThrottlingDisabled;
- VLOG(1) << "Capture size auto-throttling is now "
- << (enabled ? "enabled." : "disabled.");
- // When not auto-throttling, have the CaptureResolutionChooser target the max
- // resolution within constraints.
- if (!enabled)
- resolution_chooser_.SetTargetFrameArea(std::numeric_limits<int>::max());
- if (next_frame_number_ > 0)
- CommitCaptureSizeAndReset(GetFrameTimestamp(next_frame_number_ - 1));
- }
- void VideoCaptureOracle::SetSourceSize(const gfx::Size& source_size) {
- resolution_chooser_.SetSourceSize(source_size);
- // If the |resolution_chooser_| computed a new capture size, that will become
- // visible via a future call to ObserveEventAndDecideCapture().
- source_size_change_time_ = (next_frame_number_ == 0) ?
- base::TimeTicks() : GetFrameTimestamp(next_frame_number_ - 1);
- }
- bool VideoCaptureOracle::ObserveEventAndDecideCapture(
- Event event,
- const gfx::Rect& damage_rect,
- base::TimeTicks event_time) {
- DCHECK_GE(event, 0);
- DCHECK_LT(event, kNumEvents);
- if (event_time < last_event_time_[event]) {
- LOG(WARNING) << "Event time is not monotonically non-decreasing. "
- << "Deciding not to capture this frame.";
- return false;
- }
- last_event_time_[event] = event_time;
- bool should_sample = false;
- duration_of_next_frame_ = base::TimeDelta();
- switch (event) {
- // Refresh demands get the same priority as compositor updates.
- case kRefreshDemand:
- [[fallthrough]];
- case kCompositorUpdate: {
- smoothing_sampler_.ConsiderPresentationEvent(event_time);
- const bool had_proposal = content_sampler_.HasProposal();
- content_sampler_.ConsiderPresentationEvent(damage_rect, event_time);
- if (content_sampler_.HasProposal()) {
- VLOG_IF(1, !had_proposal) << "Content sampler now detects animation.";
- should_sample = content_sampler_.ShouldSample();
- if (should_sample) {
- event_time = content_sampler_.frame_timestamp();
- duration_of_next_frame_ = content_sampler_.sampling_period();
- }
- last_time_animation_was_detected_ = event_time;
- } else {
- VLOG_IF(1, had_proposal) << "Content sampler detects animation ended.";
- should_sample = smoothing_sampler_.ShouldSample();
- }
- break;
- }
- case kRefreshRequest:
- // Only allow non-compositor samplings when content has not recently been
- // animating, and only if there are no samplings currently in progress.
- if (num_frames_pending_ == 0) {
- if (!content_sampler_.HasProposal() ||
- ((event_time - last_time_animation_was_detected_) >
- kAnimationHaltPeriodBeforeCaptureAllowed)) {
- smoothing_sampler_.ConsiderPresentationEvent(event_time);
- should_sample = smoothing_sampler_.ShouldSample();
- }
- }
- break;
- case kNumEvents:
- NOTREACHED();
- break;
- }
- if (!should_sample)
- return false;
- // If the exact duration of the next frame has not been determined, estimate
- // it using the difference between the current and last frame.
- if (duration_of_next_frame_.is_zero()) {
- if (next_frame_number_ > 0) {
- duration_of_next_frame_ =
- event_time - GetFrameTimestamp(next_frame_number_ - 1);
- }
- duration_of_next_frame_ = std::max(
- std::min(duration_of_next_frame_, kUpperBoundsDurationEstimate),
- min_capture_period());
- }
- // Update |capture_size_| and reset all feedback signal accumulators if
- // either: 1) this is the first frame; or 2) |resolution_chooser_| has an
- // updated capture size and sufficient time has passed since the last size
- // change.
- if (next_frame_number_ == 0) {
- CommitCaptureSizeAndReset(event_time - duration_of_next_frame_);
- } else if (capture_size_ != resolution_chooser_.capture_size()) {
- const base::TimeDelta time_since_last_change =
- event_time - buffer_pool_utilization_.reset_time();
- if (time_since_last_change >= min_size_change_period_ ||
- capture_size_throttling_mode_ != kThrottlingActive) {
- // Unless autothrottling has become active resolution should be changed
- // ASAP.
- CommitCaptureSizeAndReset(GetFrameTimestamp(next_frame_number_ - 1));
- }
- }
- SetFrameTimestamp(next_frame_number_, event_time);
- return true;
- }
- void VideoCaptureOracle::RecordCapture(double pool_utilization) {
- DCHECK(std::isfinite(pool_utilization) && pool_utilization >= 0.0);
- smoothing_sampler_.RecordSample();
- const base::TimeTicks timestamp = GetFrameTimestamp(next_frame_number_);
- content_sampler_.RecordSample(timestamp);
- if (capture_size_throttling_mode_ == kThrottlingActive) {
- buffer_pool_utilization_.Update(pool_utilization, timestamp);
- AnalyzeAndAdjust(timestamp);
- }
- num_frames_pending_++;
- next_frame_number_++;
- }
- void VideoCaptureOracle::RecordWillNotCapture(double pool_utilization) {
- VLOG(1) << "Client rejects proposal to capture frame (at #"
- << next_frame_number_ << ").";
- if (capture_size_throttling_mode_ == kThrottlingActive) {
- DCHECK(std::isfinite(pool_utilization) && pool_utilization >= 0.0);
- const base::TimeTicks timestamp = GetFrameTimestamp(next_frame_number_);
- buffer_pool_utilization_.Update(pool_utilization, timestamp);
- AnalyzeAndAdjust(timestamp);
- }
- // Note: Do not advance |next_frame_number_| since it will be re-used for the
- // next capture proposal.
- }
- bool VideoCaptureOracle::CompleteCapture(int frame_number,
- bool capture_was_successful,
- base::TimeTicks* frame_timestamp) {
- num_frames_pending_--;
- DCHECK_GE(num_frames_pending_, 0);
- // Drop frame if previously delivered frame number is higher.
- if (last_successfully_delivered_frame_number_ > frame_number) {
- LOG_IF(WARNING, capture_was_successful)
- << "Out of order frame delivery detected (have #" << frame_number
- << ", last was #" << last_successfully_delivered_frame_number_
- << "). Dropping frame.";
- return false;
- }
- if (!IsFrameInRecentHistory(frame_number)) {
- LOG(WARNING) << "Very old capture being ignored: frame #" << frame_number;
- return false;
- }
- if (!capture_was_successful) {
- VLOG(2) << "Capture of frame #" << frame_number << " was not successful.";
- return false;
- }
- DCHECK_NE(last_successfully_delivered_frame_number_, frame_number);
- last_successfully_delivered_frame_number_ = frame_number;
- *frame_timestamp = GetFrameTimestamp(frame_number);
- // If enabled, log a measurement of how this frame timestamp has incremented
- // in relation to an ideal increment.
- if (VLOG_IS_ON(3) && frame_number > 0) {
- const base::TimeDelta delta =
- *frame_timestamp - GetFrameTimestamp(frame_number - 1);
- if (content_sampler_.HasProposal()) {
- const double estimated_frame_rate =
- 1000000.0 / content_sampler_.detected_period().InMicroseconds();
- const int rounded_frame_rate =
- static_cast<int>(estimated_frame_rate + 0.5);
- VLOG_STREAM(3) << base::StringPrintf(
- "Captured #%d: delta=%" PRId64
- " usec"
- ", now locked into {%s}, %+0.1f%% slower than %d FPS",
- frame_number, delta.InMicroseconds(),
- content_sampler_.detected_region().ToString().c_str(),
- 100.0 * FractionFromExpectedFrameRate(delta, rounded_frame_rate),
- rounded_frame_rate);
- } else {
- VLOG_STREAM(3) << base::StringPrintf(
- "Captured #%d: delta=%" PRId64
- " usec"
- ", d/30fps=%+0.1f%%, d/25fps=%+0.1f%%, d/24fps=%+0.1f%%",
- frame_number, delta.InMicroseconds(),
- 100.0 * FractionFromExpectedFrameRate(delta, 30),
- 100.0 * FractionFromExpectedFrameRate(delta, 25),
- 100.0 * FractionFromExpectedFrameRate(delta, 24));
- }
- }
- return true;
- }
- void VideoCaptureOracle::CancelAllCaptures() {
- // The following is the desired behavior:
- //
- // for (int i = num_frames_pending_; i > 0; --i) {
- // CompleteCapture(next_frame_number_ - i, false, nullptr);
- // --num_frames_pending_;
- // }
- //
- // ...which simplifies to:
- num_frames_pending_ = 0;
- }
- void VideoCaptureOracle::RecordConsumerFeedback(
- int frame_number,
- const media::VideoCaptureFeedback& feedback) {
- // Max frame-rate constraint.
- base::TimeDelta period;
- if (std::isfinite(feedback.max_framerate_fps) &&
- feedback.max_framerate_fps > 0.0) {
- period =
- std::max(min_capture_period_, base::Hertz(feedback.max_framerate_fps));
- } else {
- period = min_capture_period_;
- }
- smoothing_sampler_.SetMinCapturePeriod(period);
- content_sampler_.SetMinCapturePeriod(period);
- // Max pixels constraint. Only respected if auto-throttling is off because
- // consumers could just rescale the image.
- if (capture_size_throttling_mode_ != kThrottlingActive) {
- int limit;
- if (feedback.max_pixels < std::numeric_limits<int>::max()) {
- // +1 so that |FindSmallerFrameSize| could return exact |max_pixels| size.
- limit = feedback.max_pixels + 1;
- } else {
- limit = std::numeric_limits<int>::max();
- }
- int area = resolution_chooser_.FindSmallerFrameSize(limit, 1).GetArea();
- resolution_chooser_.SetTargetFrameArea(area);
- }
- // resource_utilization feedback.
- if (capture_size_throttling_mode_ == kThrottlingDisabled)
- return;
- if (!std::isfinite(feedback.resource_utilization)) {
- LOG(DFATAL) << "Non-finite utilization provided by consumer for frame #"
- << frame_number << ": " << feedback.resource_utilization;
- return;
- }
- if (feedback.resource_utilization <= 0.0)
- return; // Non-positive values are normal, meaning N/A.
- if (capture_size_throttling_mode_ != kThrottlingActive) {
- VLOG(1) << "Received consumer feedback at frame #" << frame_number
- << "; activating capture size auto-throttling.";
- capture_size_throttling_mode_ = kThrottlingActive;
- }
- if (!IsFrameInRecentHistory(frame_number)) {
- VLOG(1) << "Very old frame feedback being ignored: frame #" << frame_number;
- return;
- }
- const base::TimeTicks timestamp = GetFrameTimestamp(frame_number);
- // Translate the utilization metric to be in terms of the capable frame area
- // and update the feedback accumulators. Research suggests utilization is at
- // most linearly proportional to area, and typically is sublinear. Either
- // way, the end-to-end system should converge to the right place using the
- // more-conservative assumption (linear).
- const int area_at_full_utilization = base::saturated_cast<int>(
- capture_size_.GetArea() / feedback.resource_utilization);
- estimated_capable_area_.Update(area_at_full_utilization, timestamp);
- }
- void VideoCaptureOracle::SetMinSizeChangePeriod(base::TimeDelta period) {
- min_size_change_period_ = period;
- }
- gfx::Size VideoCaptureOracle::capture_size() const {
- return capture_size_;
- }
- // static
- const char* VideoCaptureOracle::EventAsString(Event event) {
- switch (event) {
- case kCompositorUpdate:
- return "compositor";
- case kRefreshRequest:
- return "refresh";
- case kRefreshDemand:
- return "demand";
- case kNumEvents:
- break;
- }
- NOTREACHED();
- return "unknown";
- }
- base::TimeTicks VideoCaptureOracle::GetFrameTimestamp(int frame_number) const {
- DCHECK(IsFrameInRecentHistory(frame_number));
- return frame_timestamps_[frame_number % kMaxFrameTimestamps];
- }
- void VideoCaptureOracle::SetFrameTimestamp(int frame_number,
- base::TimeTicks timestamp) {
- DCHECK(IsFrameInRecentHistory(frame_number));
- frame_timestamps_[frame_number % kMaxFrameTimestamps] = timestamp;
- }
- NOINLINE bool VideoCaptureOracle::IsFrameInRecentHistory(
- int frame_number) const {
- // Adding (next_frame_number_ >= 0) helps the compiler deduce that there
- // is no possibility of overflow here. NOINLINE is also required to ensure the
- // compiler can make this deduction (some compilers fail to otherwise...).
- return (frame_number >= 0 && next_frame_number_ >= 0 &&
- frame_number <= next_frame_number_ &&
- (next_frame_number_ - frame_number) < kMaxFrameTimestamps);
- }
- void VideoCaptureOracle::CommitCaptureSizeAndReset(
- base::TimeTicks last_frame_time) {
- capture_size_ = resolution_chooser_.capture_size();
- VLOG(2) << "Now proposing a capture size of " << capture_size_.ToString();
- // Reset each short-term feedback accumulator with a stable-state starting
- // value.
- const base::TimeTicks ignore_before_time = JustAfter(last_frame_time);
- buffer_pool_utilization_.Reset(1.0, ignore_before_time);
- estimated_capable_area_.Reset(capture_size_.GetArea(), ignore_before_time);
- }
- void VideoCaptureOracle::AnalyzeAndAdjust(const base::TimeTicks analyze_time) {
- DCHECK(capture_size_throttling_mode_ == kThrottlingActive);
- const int decreased_area = AnalyzeForDecreasedArea(analyze_time);
- if (decreased_area > 0) {
- resolution_chooser_.SetTargetFrameArea(decreased_area);
- if (!emit_log_message_cb_.is_null()) {
- emit_log_message_cb_.Run(base::StringPrintf(
- "VFC: CaptureOracle - Decreasing resolution. "
- "buffer_utilization_: %lf "
- "estimated_cappable_area: %lf "
- "capture_size: %s ",
- buffer_pool_utilization_.current(), estimated_capable_area_.current(),
- capture_size_.ToString().c_str()));
- }
- return;
- }
- const int increased_area = AnalyzeForIncreasedArea(analyze_time);
- if (increased_area > 0) {
- resolution_chooser_.SetTargetFrameArea(increased_area);
- return;
- }
- // Explicitly set the target frame area to the current capture area. This
- // cancels-out the results of a previous call to this method, where the
- // |resolution_chooser_| may have been instructed to increase or decrease the
- // capture size. Conditions may have changed since then which indicate no
- // change should be committed (via CommitCaptureSizeAndReset()).
- resolution_chooser_.SetTargetFrameArea(capture_size_.GetArea());
- }
- int VideoCaptureOracle::AnalyzeForDecreasedArea(base::TimeTicks analyze_time) {
- const int current_area = capture_size_.GetArea();
- DCHECK_GT(current_area, 0);
- // Translate the recent-average buffer pool utilization to be in terms of
- // "capable number of pixels per frame," for an apples-to-apples comparison
- // below.
- int buffer_capable_area;
- if (HasSufficientRecentFeedback(buffer_pool_utilization_, analyze_time) &&
- buffer_pool_utilization_.current() > 1.0) {
- // This calculation is hand-wavy, but seems to work well in a variety of
- // situations.
- buffer_capable_area =
- static_cast<int>(current_area / buffer_pool_utilization_.current());
- } else {
- buffer_capable_area = current_area;
- }
- int consumer_capable_area;
- if (HasSufficientRecentFeedback(estimated_capable_area_, analyze_time)) {
- consumer_capable_area =
- base::saturated_cast<int>(estimated_capable_area_.current());
- } else {
- consumer_capable_area = current_area;
- }
- // If either of the "capable areas" is less than the current capture area,
- // decrease the capture area by AT LEAST one step.
- int decreased_area = -1;
- const int capable_area = std::min(buffer_capable_area, consumer_capable_area);
- if (capable_area < current_area) {
- decreased_area = std::min(
- capable_area,
- resolution_chooser_.FindSmallerFrameSize(current_area, 1).GetArea());
- VLOG_IF(2, !start_time_of_underutilization_.is_null())
- << "Contiguous period of under-utilization ends: "
- "System is suddenly over-utilized.";
- start_time_of_underutilization_ = base::TimeTicks();
- VLOG(2) << "Proposing a "
- << (100.0 * (current_area - decreased_area) / current_area)
- << "% decrease in capture area. :-(";
- }
- // Always log the capability interpretations at verbose logging level 3. At
- // level 2, only log when when proposing a decreased area.
- VLOG(decreased_area == -1 ? 3 : 2)
- << "Capability of pool=" << (100.0 * buffer_capable_area / current_area)
- << "%, consumer=" << (100.0 * consumer_capable_area / current_area)
- << '%';
- return decreased_area;
- }
- int VideoCaptureOracle::AnalyzeForIncreasedArea(base::TimeTicks analyze_time) {
- // Compute what one step up in capture size/area would be. If the current
- // area is already at the maximum, no further analysis is necessary.
- const int current_area = capture_size_.GetArea();
- const int increased_area =
- resolution_chooser_.FindLargerFrameSize(current_area, 1).GetArea();
- if (increased_area <= current_area)
- return -1;
- // Determine whether the buffer pool could handle an increase in area.
- if (!HasSufficientRecentFeedback(buffer_pool_utilization_, analyze_time))
- return -1;
- if (buffer_pool_utilization_.current() > 0.0) {
- const int buffer_capable_area = base::saturated_cast<int>(
- current_area / buffer_pool_utilization_.current());
- if (buffer_capable_area < increased_area) {
- VLOG_IF(2, !start_time_of_underutilization_.is_null())
- << "Contiguous period of under-utilization ends: "
- "Buffer pool is no longer under-utilized.";
- start_time_of_underutilization_ = base::TimeTicks();
- return -1; // Buffer pool is not under-utilized.
- }
- }
- // Determine whether the consumer could handle an increase in area.
- if (HasSufficientRecentFeedback(estimated_capable_area_, analyze_time)) {
- if (estimated_capable_area_.current() < increased_area) {
- VLOG_IF(2, !start_time_of_underutilization_.is_null())
- << "Contiguous period of under-utilization ends: "
- "Consumer is no longer under-utilized.";
- start_time_of_underutilization_ = base::TimeTicks();
- return -1; // Consumer is not under-utilized.
- }
- } else if (estimated_capable_area_.update_time() ==
- estimated_capable_area_.reset_time()) {
- // The consumer does not provide any feedback. In this case, the consumer's
- // capability isn't a consideration.
- } else {
- // Consumer is providing feedback, but hasn't reported it recently. Just in
- // case it's stalled, don't make things worse by increasing the capture
- // area.
- return -1;
- }
- // At this point, the system is currently under-utilized. Reset the start
- // time if the system was not under-utilized when the last analysis was made.
- if (start_time_of_underutilization_.is_null())
- start_time_of_underutilization_ = analyze_time;
- // If the under-utilization started soon after the last source size change,
- // permit an immediate increase in the capture area. This allows the system
- // to quickly step-up to an ideal point.
- if (start_time_of_underutilization_ - source_size_change_time_ <=
- GetExplorationPeriodAfterSourceSizeChange()) {
- VLOG(2) << "Proposing a "
- << (100.0 * (increased_area - current_area) / current_area)
- << "% increase in capture area after source size change. :-)";
- return increased_area;
- }
- // While content is animating, require a "proving period" of contiguous
- // under-utilization before increasing the capture area. This will mitigate
- // the risk of frames getting dropped when the data volume increases.
- if ((analyze_time - last_time_animation_was_detected_) <
- kDebouncingPeriodForAnimatedContent) {
- if ((analyze_time - start_time_of_underutilization_) <
- kProvingPeriodForAnimatedContent) {
- // Content is animating but the system needs to be under-utilized for a
- // longer period of time.
- return -1;
- } else {
- // Content is animating and the system has been contiguously
- // under-utilized for a good long time.
- VLOG(2) << "Proposing a *cautious* "
- << (100.0 * (increased_area - current_area) / current_area)
- << "% increase in capture area while content is animating. :-)";
- // Reset the "proving period."
- start_time_of_underutilization_ = base::TimeTicks();
- return increased_area;
- }
- }
- // Content is not animating, so permit an immediate increase in the capture
- // area. This allows the system to quickly improve the quality of
- // non-animating content (frame drops are not much of a concern).
- VLOG(2) << "Proposing a "
- << (100.0 * (increased_area - current_area) / current_area)
- << "% increase in capture area for non-animating content. :-)";
- return increased_area;
- }
- base::TimeDelta
- VideoCaptureOracle::GetExplorationPeriodAfterSourceSizeChange() {
- return 3 * min_size_change_period_;
- }
- bool VideoCaptureOracle::HasSufficientRecentFeedback(
- const FeedbackSignalAccumulator<base::TimeTicks>& accumulator,
- base::TimeTicks now) {
- const base::TimeDelta amount_of_history =
- accumulator.update_time() - accumulator.reset_time();
- return (amount_of_history >= min_size_change_period_) &&
- (now - accumulator.update_time() <= kMaxTimeSinceLastFeedbackUpdate);
- }
- void VideoCaptureOracle::SetLogCallback(
- base::RepeatingCallback<void(const std::string&)> emit_log_cb) {
- emit_log_message_cb_ = std::move(emit_log_cb);
- }
- } // namespace media
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