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// Copyright 2020 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 "cast/streaming/capture_recommendations.h"
#include <algorithm>
#include <utility>
#include "cast/streaming/answer_messages.h"
#include "util/osp_logging.h"
namespace openscreen {
namespace cast {
namespace capture_recommendations {
namespace {
void ApplyDisplay(const DisplayDescription& description,
Recommendations* recommendations) {
recommendations->video.supports_scaling =
(description.aspect_ratio_constraint &&
(description.aspect_ratio_constraint.value() ==
AspectRatioConstraint::kVariable));
// We should never exceed the display's resolution, since it will always
// force scaling.
if (description.dimensions) {
recommendations->video.maximum = description.dimensions.value();
recommendations->video.bit_rate_limits.maximum =
recommendations->video.maximum.effective_bit_rate();
if (recommendations->video.maximum.width <
recommendations->video.minimum.width) {
recommendations->video.minimum =
recommendations->video.maximum.ToResolution();
}
}
// If the receiver gives us an aspect ratio that doesn't match the display
// resolution they give us, the behavior is undefined from the spec.
// Here we prioritize the aspect ratio, and the receiver can scale the frame
// as they wish.
double aspect_ratio = 0.0;
if (description.aspect_ratio) {
aspect_ratio = static_cast<double>(description.aspect_ratio->width) /
description.aspect_ratio->height;
recommendations->video.maximum.width =
recommendations->video.maximum.height * aspect_ratio;
} else if (description.dimensions) {
aspect_ratio = static_cast<double>(description.dimensions->width) /
description.dimensions->height;
} else {
return;
}
recommendations->video.minimum.width =
recommendations->video.minimum.height * aspect_ratio;
}
void ApplyConstraints(const Constraints& constraints,
Recommendations* recommendations) {
// Audio has no fields in the display description, so we can safely
// ignore the current recommendations when setting values here.
if (constraints.audio.max_delay.has_value()) {
recommendations->audio.max_delay = constraints.audio.max_delay.value();
}
recommendations->audio.max_channels = constraints.audio.max_channels;
recommendations->audio.max_sample_rate = constraints.audio.max_sample_rate;
recommendations->audio.bit_rate_limits = BitRateLimits{
std::max(constraints.audio.min_bit_rate, kDefaultAudioMinBitRate),
std::max(constraints.audio.max_bit_rate, kDefaultAudioMinBitRate)};
// With video, we take the intersection of values of the constraints and
// the display description.
if (constraints.video.max_delay.has_value()) {
recommendations->video.max_delay = constraints.video.max_delay.value();
}
if (constraints.video.max_pixels_per_second.has_value()) {
recommendations->video.max_pixels_per_second =
constraints.video.max_pixels_per_second.value();
}
recommendations->video.bit_rate_limits =
BitRateLimits{std::max(constraints.video.min_bit_rate,
recommendations->video.bit_rate_limits.minimum),
std::min(constraints.video.max_bit_rate,
recommendations->video.bit_rate_limits.maximum)};
Dimensions dimensions = constraints.video.max_dimensions;
if (dimensions.width <= kDefaultMinResolution.width) {
recommendations->video.maximum = {kDefaultMinResolution.width,
kDefaultMinResolution.height,
kDefaultFrameRate};
} else if (dimensions.width < recommendations->video.maximum.width) {
recommendations->video.maximum = std::move(dimensions);
}
if (constraints.video.min_resolution) {
const Resolution& min = constraints.video.min_resolution->ToResolution();
if (kDefaultMinResolution.width < min.width) {
recommendations->video.minimum = std::move(min);
}
}
}
} // namespace
bool BitRateLimits::operator==(const BitRateLimits& other) const {
return std::tie(minimum, maximum) == std::tie(other.minimum, other.maximum);
}
bool Audio::operator==(const Audio& other) const {
return std::tie(bit_rate_limits, max_delay, max_channels, max_sample_rate) ==
std::tie(other.bit_rate_limits, other.max_delay, other.max_channels,
other.max_sample_rate);
}
bool Video::operator==(const Video& other) const {
return std::tie(bit_rate_limits, minimum, maximum, supports_scaling,
max_delay, max_pixels_per_second) ==
std::tie(other.bit_rate_limits, other.minimum, other.maximum,
other.supports_scaling, other.max_delay,
other.max_pixels_per_second);
}
bool Recommendations::operator==(const Recommendations& other) const {
return std::tie(audio, video) == std::tie(other.audio, other.video);
}
Recommendations GetRecommendations(const Answer& answer) {
Recommendations recommendations;
if (answer.display.has_value() && answer.display->IsValid()) {
ApplyDisplay(answer.display.value(), &recommendations);
}
if (answer.constraints.has_value() && answer.constraints->IsValid()) {
ApplyConstraints(answer.constraints.value(), &recommendations);
}
return recommendations;
}
} // namespace capture_recommendations
} // namespace cast
} // namespace openscreen
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