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/*
* Copyright (c) 2012 The WebRTC project authors. All Rights Reserved.
*
* Use of this source code is governed by a BSD-style license
* that can be found in the LICENSE file in the root of the source
* tree. An additional intellectual property rights grant can be found
* in the file PATENTS. All contributing project authors may
* be found in the AUTHORS file in the root of the source tree.
*/
#include "video/encoder_rtcp_feedback.h"
#include <algorithm>
#include <utility>
#include "absl/types/optional.h"
#include "api/video_codecs/video_encoder.h"
#include "rtc_base/checks.h"
#include "rtc_base/experiments/keyframe_interval_settings.h"
namespace webrtc {
namespace {
constexpr int kMinKeyframeSendIntervalMs = 300;
} // namespace
EncoderRtcpFeedback::EncoderRtcpFeedback(
Clock* clock,
const std::vector<uint32_t>& ssrcs,
VideoStreamEncoderInterface* encoder,
std::function<std::vector<RtpSequenceNumberMap::Info>(
uint32_t ssrc,
const std::vector<uint16_t>& seq_nums)> get_packet_infos)
: clock_(clock),
ssrcs_(ssrcs),
get_packet_infos_(std::move(get_packet_infos)),
video_stream_encoder_(encoder),
time_last_packet_delivery_queue_(Timestamp::Zero()),
min_keyframe_send_interval_(
TimeDelta::Millis(KeyframeIntervalSettings::ParseFromFieldTrials()
.MinKeyframeSendIntervalMs()
.value_or(kMinKeyframeSendIntervalMs))) {
RTC_DCHECK(!ssrcs.empty());
packet_delivery_queue_.Detach();
}
// Called via Call::DeliverRtcp.
void EncoderRtcpFeedback::OnReceivedIntraFrameRequest(uint32_t ssrc) {
RTC_DCHECK_RUN_ON(&packet_delivery_queue_);
RTC_DCHECK(std::find(ssrcs_.begin(), ssrcs_.end(), ssrc) != ssrcs_.end());
const Timestamp now = clock_->CurrentTime();
if (time_last_packet_delivery_queue_ + min_keyframe_send_interval_ > now)
return;
time_last_packet_delivery_queue_ = now;
// Always produce key frame for all streams.
video_stream_encoder_->SendKeyFrame();
}
void EncoderRtcpFeedback::OnReceivedLossNotification(
uint32_t ssrc,
uint16_t seq_num_of_last_decodable,
uint16_t seq_num_of_last_received,
bool decodability_flag) {
RTC_DCHECK(get_packet_infos_) << "Object initialization incomplete.";
const std::vector<uint16_t> seq_nums = {seq_num_of_last_decodable,
seq_num_of_last_received};
const std::vector<RtpSequenceNumberMap::Info> infos =
get_packet_infos_(ssrc, seq_nums);
if (infos.empty()) {
return;
}
RTC_DCHECK_EQ(infos.size(), 2u);
const RtpSequenceNumberMap::Info& last_decodable = infos[0];
const RtpSequenceNumberMap::Info& last_received = infos[1];
VideoEncoder::LossNotification loss_notification;
loss_notification.timestamp_of_last_decodable = last_decodable.timestamp;
loss_notification.timestamp_of_last_received = last_received.timestamp;
// Deduce decodability of the last received frame and of its dependencies.
if (last_received.is_first && last_received.is_last) {
// The frame consists of a single packet, and that packet has evidently
// been received in full; the frame is therefore assemblable.
// In this case, the decodability of the dependencies is communicated by
// the decodability flag, and the frame itself is decodable if and only
// if they are decodable.
loss_notification.dependencies_of_last_received_decodable =
decodability_flag;
loss_notification.last_received_decodable = decodability_flag;
} else if (last_received.is_first && !last_received.is_last) {
// In this case, the decodability flag communicates the decodability of
// the dependencies. If any is undecodable, we also know that the frame
// itself will not be decodable; if all are decodable, the frame's own
// decodability will remain unknown, as not all of its packets have
// been received.
loss_notification.dependencies_of_last_received_decodable =
decodability_flag;
loss_notification.last_received_decodable =
!decodability_flag ? absl::make_optional(false) : absl::nullopt;
} else if (!last_received.is_first && last_received.is_last) {
if (decodability_flag) {
// The frame has been received in full, and found to be decodable.
// (Messages of this type are not sent by WebRTC at the moment, but are
// theoretically possible, for example for serving as acks.)
loss_notification.dependencies_of_last_received_decodable = true;
loss_notification.last_received_decodable = true;
} else {
// It is impossible to tell whether some dependencies were undecodable,
// or whether the frame was unassemblable, but in either case, the frame
// itself was undecodable.
loss_notification.dependencies_of_last_received_decodable = absl::nullopt;
loss_notification.last_received_decodable = false;
}
} else { // !last_received.is_first && !last_received.is_last
if (decodability_flag) {
// The frame has not yet been received in full, but no gaps have
// been encountered so far, and the dependencies were all decodable.
// (Messages of this type are not sent by WebRTC at the moment, but are
// theoretically possible, for example for serving as acks.)
loss_notification.dependencies_of_last_received_decodable = true;
loss_notification.last_received_decodable = absl::nullopt;
} else {
// It is impossible to tell whether some dependencies were undecodable,
// or whether the frame was unassemblable, but in either case, the frame
// itself was undecodable.
loss_notification.dependencies_of_last_received_decodable = absl::nullopt;
loss_notification.last_received_decodable = false;
}
}
video_stream_encoder_->OnLossNotification(loss_notification);
}
} // namespace webrtc
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