enable red by default (#940)

* enable red by default

* fix test case

pkg/config/config.go

@@ -235,6 +235,7 @@ func NewConfig(confString string, c *cli.Context) (*Config, error) {
 			AutoCreate: true,
 			EnabledCodecs: []CodecSpec{
 				{Mime: webrtc.MimeTypeOpus},
+				{Mime: "audio/red"},
 				{Mime: webrtc.MimeTypeVP8},
 				{Mime: webrtc.MimeTypeH264},
 				// {Mime: webrtc.MimeTypeAV1},

pkg/rtc/clientinfo.go

@@ -7,5 +7,5 @@ type ClientInfo struct {
 }
 
 func (c ClientInfo) SupportsAudioRED() bool {
-	return c.ClientInfo.Browser != "firefox" && c.ClientInfo.Browser != "safari"
+	return c.ClientInfo != nil && c.ClientInfo.Browser != "firefox" && c.ClientInfo.Browser != "safari"
 }

pkg/rtc/mediaengine.go

@@ -6,6 +6,7 @@ import (
 
 	"github.com/pion/webrtc/v3"
 
+	"github.com/livekit/livekit-server/pkg/sfu"
 	"github.com/livekit/protocol/livekit"
 )
 
@@ -24,7 +25,7 @@ func registerCodecs(me *webrtc.MediaEngine, codecs []*livekit.Codec, rtcpFeedbac
 			return err
 		}
 	}
-	redCodec := webrtc.RTPCodecCapability{MimeType: "audio/red", ClockRate: 48000, Channels: 2}
+	redCodec := webrtc.RTPCodecCapability{MimeType: sfu.MimeTypeAudioRed, ClockRate: 48000, Channels: 2}
 	if opusPayload != 0 && isCodecEnabled(codecs, redCodec) {
 		redCodec.SDPFmtpLine = fmt.Sprintf("%d/%d", opusPayload, opusPayload)
 		if err := me.RegisterCodec(webrtc.RTPCodecParameters{

pkg/rtc/participant_internal_test.go

@@ -434,6 +434,7 @@ type participantOpts struct {
 	protocolVersion types.ProtocolVersion
 	publisher       bool
 	clientConf      *livekit.ClientConfiguration
+	clientInfo      *livekit.ClientInfo
 }
 
 func newParticipantForTestWithOpts(identity livekit.ParticipantIdentity, opts *participantOpts) *ParticipantImpl {
@@ -477,6 +478,7 @@ func newParticipantForTestWithOpts(identity livekit.ParticipantIdentity, opts *p
 		Grants:            grants,
 		EnabledCodecs:     enabledCodecs,
 		ClientConf:        opts.clientConf,
+		ClientInfo:        ClientInfo{ClientInfo: opts.clientInfo},
 	})
 	p.isPublisher.Store(opts.publisher)
 

pkg/sfu/redprimaryreceiver.go

@@ -84,6 +84,10 @@ func (r *RedPrimaryReceiver) DeleteDownTrack(subscriberID livekit.ParticipantID)
 	r.downTrackSpreader.Free(subscriberID)
 }
 
+func (r *RedPrimaryReceiver) CanClose() bool {
+	return r.closed.Load() || r.downTrackSpreader.DownTrackCount() == 0
+}
+
 func (r *RedPrimaryReceiver) Close() {
 	r.closed.Store(true)
 	for _, dt := range r.downTrackSpreader.ResetAndGetDownTracks() {