s=>start\ne=>end\ns1=>operation: send rtp with TWCC header\ns2=>operation: receive rtp packet\ns3=>operation: compose TWCC feedback\ns4=>operation: send rtcp packet\ns5=>operation: receive rtcp packet\ns6=>operation: parse rtcp packet\ns7=>operation: bandwidth estimate\ns8=>operation: adjust send bitrate\n\ns->s1->s2->s3->s4->s5->s6->s7->s8->e<\/code><\/pre>\n\u4e3b\u8981\u7684\u903b\u8f91\u5728\u53d1\u9001\u65b9<\/p>\n
![\"file\"](\"https:\/\/www.fanyamin.com\/wordpress\/wp-content\/uploads\/2022\/03\/image-1647136811501.png\")
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title WebRTC congestion control v1\n\nparticipant RtpSender as sender\nparticipant CongestionController as controller\nparticipant TransportFeedbackAdpater as adapter\nparticipant AcknowledgedBitrateEstimator as ack_estimator\nparticipant ProbeController as probe_controller\nparticipant DelayBasedBwe as delay_based_bwe\nparticipant BitrateController as bitrate_controller\n\nautonumber\n\n->sender: ReceiveRtcp\n\nalt RTCP of transport feedback\n sender->controller: OnTransportFeedback(feedback)\n controller->adapter: onTransportFeedback(feedback)\nend\n\nalt currently_in_alr\n controller->ack_estimator: SetAlrEndedTimeMs(now_ms)\n controller->probe_controller: SetAlrEndedTimeMs(now_ms)\nend\n\ncontroller->ack_estimator: IncomingPacketFeedbackVector(feedback_vector)\ncontroller->ack_estimator: bitrate_bps()\ncontroller->delay_based_bwe:IncomingPacketFeedbackVector(...)\ndelay_based_bwe-->controller: result\n\nalt result.updated\n controller->bitrate_controller: OnDelayBasedBweResult(result)\n controller->controller: MaybeTriggerOnNetworkChanged()\nend\n\nalt result.recovered_from_overuse\n controller->probe_controller: RequestProbe()\nend\n\nalt in_cwnd_experiment\n controller->controller: LimitOutstandingBytes(adapter.GetOutstandingBytes())\nend<\/code><\/pre>\n![\"\"](\"https:\/\/www.fanyamin.com\/wordpress\/wp-content\/uploads\/2022\/03\/image-1647163434018.png\")
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1) \u5148\u7b97\u53cd\u9988\u786e\u8ba4\u7684\u5e26\u5bbd ack_bitrate<\/p>\n
acknowledged_bitrate_estimator_->IncomingPacketFeedbackVector(packets);<\/code><\/pre>\n2) \u518d\u7b97\u63a2\u6d4b\u7684\u5e26\u5bbd probe_bitrate<\/p>\n
probe_bitrate_estimator_->HandleProbeAndEstimateBitrate(packet);<\/code><\/pre>\n3) \u518d\u7b97\u57fa\u4e8e\u5ef6\u8fdf\u7684\u5e26\u5bbd delay_based target_bitrate<\/p>\n
NetworkControlUpdate GoogCcNetworkController::OnTransportPacketsFeedback(\n \/\/...\n result = delay_based_bwe_->IncomingPacketFeedbackVector(\n report, acknowledged_bitrate, probe_bitrate, estimate_,\n alr_start_time.has_value());\n\n}<\/code><\/pre>\n4) \u518d\u8ba1\u7b97\u57fa\u4e8e\u4e22\u5305\u7684\u5e26\u5bbd loss_based target_bitrate<\/p>\n
if (result.updated) {\n if (result.probe) {\n bandwidth_estimation_->SetSendBitrate(result.target_bitrate,\n report.feedback_time);\n }\n \/\/ Since SetSendBitrate now resets the delay-based estimate, we have to\n \/\/ call UpdateDelayBasedEstimate after SetSendBitrate.\n bandwidth_estimation_->UpdateDelayBasedEstimate(report.feedback_time,\n result.target_bitrate);\n \/\/ Update the estimate in the ProbeController, in case we want to probe.\n MaybeTriggerOnNetworkChanged(&update, report.feedback_time);\n }<\/code><\/pre>\n\u6ce8: <\/p>\n
std::unique_ptr<SendSideBandwidthEstimation> bandwidth_estimation_;<\/code><\/pre>\n1), 2) \u4e3b\u8981\u662f\u901a\u8fc7\u5b9e\u9645\u53d1\u9001\u548c\u63a5\u6536\u7684\u5b57\u8282\u6765\u8ba1\u7b97\u6d41\u91cf,\u4f30\u7b97\u5e26\u5bbd
\n3) \u901a\u8fc7\u770b\u5355\u5411\u5ef6\u8fdf\u68af\u5ea6\u7684\u53d8\u5316\u6765\u4f30\u7b97\u5e26\u5bbd, \u7efc\u5408\u8003\u8651 1) \u548c 2)
\n4) \u901a\u8fc7\u770b\u4e22\u5305\u7387\u6765\u4f30\u7b97\u5e26\u5bbd, \u4e5f\u8981\u7efc\u5408\u8003\u8651 3)<\/p>\n
Delay<\/h1>\n","protected":false},"excerpt":{"rendered":"
\u603b\u4f53\u6d41\u7a0b \u5f53\u6536\u5230 Transport Wide CC RTCP report \u65f6\u5019 \uff0c\u4f1a\u56de\u8c03 OnTransportPacketsFeedback \u65b9\u6cd5 s=>start e=>end s1=>operation: send rtp with TWCC header s2=>operation: receive rtp packet s3=>operation: compose TWCC feedback s4=>operation: send rtcp packet s5=>operation: receive rtcp packet s6=>operation: parse rtcp packet s7=>operation: bandwidth estimate s8=>operation: adjust send bitrate s->s1->s2->s3->s4->s5->s6->s7->s8->e \u4e3b\u8981\u7684\u903b\u8f91\u5728\u53d1\u9001\u65b9 title WebRTC congestion control v1 participant RtpSender […] →Read more<\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[15],"tags":[],"class_list":["post-503","post","type-post","status-publish","format-standard","hentry","category-webrtc"],"_links":{"self":[{"href":"https:\/\/www.fanyamin.com\/wordpress\/index.php?rest_route=\/wp\/v2\/posts\/503"}],"collection":[{"href":"https:\/\/www.fanyamin.com\/wordpress\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.fanyamin.com\/wordpress\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.fanyamin.com\/wordpress\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.fanyamin.com\/wordpress\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=503"}],"version-history":[{"count":14,"href":"https:\/\/www.fanyamin.com\/wordpress\/index.php?rest_route=\/wp\/v2\/posts\/503\/revisions"}],"predecessor-version":[{"id":604,"href":"https:\/\/www.fanyamin.com\/wordpress\/index.php?rest_route=\/wp\/v2\/posts\/503\/revisions\/604"}],"wp:attachment":[{"href":"https:\/\/www.fanyamin.com\/wordpress\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=503"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.fanyamin.com\/wordpress\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=503"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.fanyamin.com\/wordpress\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=503"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}