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