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/*
* Copyright (c) 2019 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.
*/
#ifndef MODULES_VIDEO_CODING_LOSS_NOTIFICATION_CONTROLLER_H_
#define MODULES_VIDEO_CODING_LOSS_NOTIFICATION_CONTROLLER_H_
#include <stdint.h>
#include <set>
#include "absl/types/optional.h"
#include "api/array_view.h"
#include "api/sequence_checker.h"
#include "modules/include/module_common_types.h"
#include "rtc_base/system/no_unique_address.h"
namespace webrtc {
class LossNotificationController {
public:
struct FrameDetails {
bool is_keyframe;
int64_t frame_id;
rtc::ArrayView<const int64_t> frame_dependencies;
};
LossNotificationController(KeyFrameRequestSender* key_frame_request_sender,
LossNotificationSender* loss_notification_sender);
~LossNotificationController();
// An RTP packet was received from the network.
// `frame` is non-null iff the packet is the first packet in the frame.
void OnReceivedPacket(uint16_t rtp_seq_num, const FrameDetails* frame);
// A frame was assembled from packets previously received.
// (Should be called even if the frame was composed of a single packet.)
void OnAssembledFrame(uint16_t first_seq_num,
int64_t frame_id,
bool discardable,
rtc::ArrayView<const int64_t> frame_dependencies);
private:
void DiscardOldInformation();
bool AllDependenciesDecodable(
rtc::ArrayView<const int64_t> frame_dependencies) const;
// When the loss of a packet or the non-decodability of a frame is detected,
// produces a key frame request or a loss notification.
// 1. `last_received_seq_num` is the last received sequence number.
// 2. `decodability_flag` refers to the frame associated with the last packet.
// It is set to `true` if and only if all of that frame's dependencies are
// known to be decodable, and the frame itself is not yet known to be
// unassemblable (i.e. no earlier parts of it were lost).
// Clarifications:
// a. In a multi-packet frame, the first packet reveals the frame's
// dependencies, but it is not yet known whether all parts of the
// current frame will be received.
// b. In a multi-packet frame, if the first packet is missed, the
// dependencies are unknown, but it is known that the frame itself
// is unassemblable.
void HandleLoss(uint16_t last_received_seq_num, bool decodability_flag);
KeyFrameRequestSender* const key_frame_request_sender_
RTC_GUARDED_BY(sequence_checker_);
LossNotificationSender* const loss_notification_sender_
RTC_GUARDED_BY(sequence_checker_);
// Tracked to avoid processing repeated frames (buggy/malicious remote).
absl::optional<int64_t> last_received_frame_id_
RTC_GUARDED_BY(sequence_checker_);
// Tracked to avoid processing repeated packets.
absl::optional<uint16_t> last_received_seq_num_
RTC_GUARDED_BY(sequence_checker_);
// Tracked in order to correctly report the potential-decodability of
// multi-packet frames.
bool current_frame_potentially_decodable_ RTC_GUARDED_BY(sequence_checker_);
// Loss notifications contain the sequence number of the first packet of
// the last decodable-and-non-discardable frame. Since this is a bit of
// a mouthful, last_decodable_non_discardable_.first_seq_num is used,
// which hopefully is a bit easier for human beings to parse
// than `first_seq_num_of_last_decodable_non_discardable_`.
struct FrameInfo {
explicit FrameInfo(uint16_t first_seq_num) : first_seq_num(first_seq_num) {}
uint16_t first_seq_num;
};
absl::optional<FrameInfo> last_decodable_non_discardable_
RTC_GUARDED_BY(sequence_checker_);
// Track which frames are decodable. Later frames are also decodable if
// all of their dependencies can be found in this container.
// (Naturally, later frames must also be assemblable to be decodable.)
std::set<int64_t> decodable_frame_ids_ RTC_GUARDED_BY(sequence_checker_);
RTC_NO_UNIQUE_ADDRESS SequenceChecker sequence_checker_;
};
} // namespace webrtc
#endif // MODULES_VIDEO_CODING_LOSS_NOTIFICATION_CONTROLLER_H_
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