mirror of
https://github.com/livekit/livekit.git
synced 2026-10-07 12:01:00 +00:00
David Chen
195adeb38c
Implements FlexFEC-03 (RFC 8627) end to end in the SFU, in both directions: - Upstream: decode FlexFEC repair packets from publishers and recover lost media in the receive buffer before forwarding (pkg/sfu/flexfec/decoder.go, pkg/sfu/buffer). Recovered packets are surfaced via Prometheus counters. - Downstream: generate FlexFEC for subscribers off the downtrack, paced alongside media (pkg/sfu/downtrack_fec.go, pkg/sfu/pacer). - Negotiation: advertise and match flexfec-03 in the media engine and transport SDP, gated by new config knobs (pkg/rtc, pkg/config, config-sample.yaml). - Telemetry: livekit_fec_* metrics for sent/received/recovered packets (pkg/telemetry/prometheus/packets.go). Tests: unit coverage for the decoder, buffer recovery, downtrack generation, and transport negotiation, plus an end-to-end integration test and the test-client support it needs (test/flexfec_test.go, test/client).
126 lines
3.3 KiB
Go
126 lines
3.3 KiB
Go
// Copyright 2026 LiveKit, Inc.
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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package rtc
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import (
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"testing"
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"github.com/pion/sdp/v3"
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"github.com/pion/webrtc/v4"
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"github.com/stretchr/testify/assert"
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"github.com/stretchr/testify/require"
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"github.com/livekit/protocol/livekit"
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"github.com/livekit/protocol/logger"
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)
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func TestFECPairsFromSDP(t *testing.T) {
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offer := `v=0
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o=- 8541913762120318441 2 IN IP4 127.0.0.1
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s=-
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t=0 0
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m=video 9 UDP/TLS/RTP/SAVPF 96 97 115
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c=IN IP4 0.0.0.0
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a=mid:0
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a=sendonly
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a=rtpmap:96 VP8/90000
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a=rtpmap:97 rtx/90000
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a=fmtp:97 apt=96
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a=rtpmap:115 flexfec-03/90000
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a=fmtp:115 repair-window=10000000
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a=ssrc-group:FID 1111 2222
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a=ssrc-group:FEC-FR 1111 3333
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a=ssrc:1111 cname:test
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a=ssrc:2222 cname:test
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a=ssrc:3333 cname:test
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`
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parsed := &sdp.SessionDescription{}
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require.NoError(t, parsed.Unmarshal([]byte(offer)))
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fecPairs := fecPairsFromSDP(parsed, logger.GetLogger())
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require.Len(t, fecPairs, 1)
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assert.Equal(t, uint32(1111), fecPairs[uint32(3333)])
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// FID pairs are not picked up as FEC
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rtxPairs := nonSimulcastRTXRepairsFromSDP(parsed, logger.GetLogger())
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require.Len(t, rtxPairs, 1)
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assert.Equal(t, uint32(1111), rtxPairs[uint32(2222)])
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}
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func TestFECPairsFromSDPNoGroups(t *testing.T) {
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offer := `v=0
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o=- 8541913762120318441 2 IN IP4 127.0.0.1
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s=-
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t=0 0
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m=video 9 UDP/TLS/RTP/SAVPF 96
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c=IN IP4 0.0.0.0
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a=mid:0
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a=sendonly
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a=rtpmap:96 VP8/90000
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a=ssrc:1111 cname:test
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`
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parsed := &sdp.SessionDescription{}
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require.NoError(t, parsed.Unmarshal([]byte(offer)))
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assert.Empty(t, fecPairsFromSDP(parsed, logger.GetLogger()))
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}
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func TestFlexFECPayloadTypeValidation(t *testing.T) {
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assert.NoError(t, validateFlexFECPayloadType(115))
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// VP8 payload type
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assert.Error(t, validateFlexFECPayloadType(96))
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// RTX slot of VP8 (pt+1)
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assert.Error(t, validateFlexFECPayloadType(97))
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// opus
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assert.Error(t, validateFlexFECPayloadType(111))
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}
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func TestMediaEngineRegistersFlexFEC(t *testing.T) {
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enabledCodecs := []*livekit.Codec{
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{Mime: "video/VP8"},
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{Mime: "video/rtx"},
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}
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for _, enabled := range []bool{false, true} {
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me, err := createMediaEngine(enabledCodecs, DirectionConfig{
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FlexFEC: FlexFECDirectionConfig{
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Enabled: enabled,
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PayloadType: 115,
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},
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RTCPFeedback: RTCPFeedbackConfig{
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Video: []webrtc.RTCPFeedback{{Type: webrtc.TypeRTCPFBTransportCC}},
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},
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}, false)
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require.NoError(t, err)
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// drive codec registration into negotiated form via an SDP round trip
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// is heavyweight, instead check via filterCodecs retention behavior
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flexfecParams := flexFECCodecParameters(115)
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filtered := filterCodecs(
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[]webrtc.RTPCodecParameters{flexfecParams},
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enabledCodecs,
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RTCPFeedbackConfig{},
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false,
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enabled,
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)
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if enabled {
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require.Len(t, filtered, 1)
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assert.Equal(t, webrtc.MimeTypeFlexFEC03, filtered[0].MimeType)
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} else {
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assert.Empty(t, filtered)
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}
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_ = me
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}
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}
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