packet_sequencer.h (2951B)
1 /* 2 * Copyright (c) 2021 The WebRTC project authors. All Rights Reserved. 3 * 4 * Use of this source code is governed by a BSD-style license 5 * that can be found in the LICENSE file in the root of the source 6 * tree. An additional intellectual property rights grant can be found 7 * in the file PATENTS. All contributing project authors may 8 * be found in the AUTHORS file in the root of the source tree. 9 */ 10 11 #ifndef MODULES_RTP_RTCP_SOURCE_PACKET_SEQUENCER_H_ 12 #define MODULES_RTP_RTCP_SOURCE_PACKET_SEQUENCER_H_ 13 14 #include <cstdint> 15 #include <optional> 16 17 #include "api/units/timestamp.h" 18 #include "modules/rtp_rtcp/include/rtp_rtcp_defines.h" 19 #include "modules/rtp_rtcp/source/rtp_packet_to_send.h" 20 #include "system_wrappers/include/clock.h" 21 22 namespace webrtc { 23 24 // Helper class used to assign RTP sequence numbers and populate some fields for 25 // padding packets based on the last sequenced packets. 26 // This class is not thread safe, the caller must provide that. 27 class PacketSequencer { 28 public: 29 // If `require_marker_before_media_padding_` is true, padding packets on the 30 // media ssrc is not allowed unless the last sequenced media packet had the 31 // marker bit set (i.e. don't insert padding packets between the first and 32 // last packets of a video frame). 33 // Packets with unknown SSRCs will be ignored. 34 PacketSequencer(uint32_t media_ssrc, 35 std::optional<uint32_t> rtx_ssrc, 36 bool require_marker_before_media_padding, 37 Clock* clock); 38 39 // Assigns sequence number, and in the case of non-RTX padding also timestamps 40 // and payload type. 41 void Sequence(RtpPacketToSend& packet); 42 43 void set_media_sequence_number(uint16_t sequence_number) { 44 media_sequence_number_ = sequence_number; 45 } 46 void set_rtx_sequence_number(uint16_t sequence_number) { 47 rtx_sequence_number_ = sequence_number; 48 } 49 50 void SetRtpState(const RtpState& state); 51 void PopulateRtpState(RtpState& state) const; 52 53 uint16_t media_sequence_number() const { return media_sequence_number_; } 54 uint16_t rtx_sequence_number() const { return rtx_sequence_number_; } 55 56 // Checks whether it is allowed to send padding on the media SSRC at this 57 // time, e.g. that we don't send padding in the middle of a video frame. 58 bool CanSendPaddingOnMediaSsrc() const; 59 60 private: 61 void UpdateLastPacketState(const RtpPacketToSend& packet); 62 void PopulatePaddingFields(RtpPacketToSend& packet); 63 64 const uint32_t media_ssrc_; 65 const std::optional<uint32_t> rtx_ssrc_; 66 const bool require_marker_before_media_padding_; 67 Clock* const clock_; 68 69 uint16_t media_sequence_number_; 70 uint16_t rtx_sequence_number_; 71 72 int8_t last_payload_type_; 73 uint32_t last_rtp_timestamp_; 74 Timestamp last_capture_time_ = Timestamp::MinusInfinity(); 75 Timestamp last_timestamp_time_ = Timestamp::MinusInfinity(); 76 bool last_packet_marker_bit_; 77 }; 78 79 } // namespace webrtc 80 81 #endif // MODULES_RTP_RTCP_SOURCE_PACKET_SEQUENCER_H_