Method updateFromRemoteDescription

mediaengine.go:606–714

Update the MediaEngine from a remote description.

(desc sdp.SessionDescription)

// Update the MediaEngine from a remote description.
func (m *MediaEngine) updateFromRemoteDescription(desc sdp.SessionDescription) error { //nolint:cyclop,gocognit
	m.mu.Lock()
	defer m.mu.Unlock()

	for _, media := range desc.MediaDescriptions {
		var typ RTPCodecType

		switch {
		case strings.EqualFold(media.MediaName.Media, "audio"):
			typ = RTPCodecTypeAudio
		case strings.EqualFold(media.MediaName.Media, "video"):
			typ = RTPCodecTypeVideo
		}

		switch {
		case !m.negotiatedAudio && typ == RTPCodecTypeAudio:
			m.negotiatedAudio = true
		case !m.negotiatedVideo && typ == RTPCodecTypeVideo:
			m.negotiatedVideo = true
		default:
			// update header extesions from remote sdp if codec is negotiated, Firefox
			// would send updated header extension in renegotiation.
			// e.g. publish first track without simucalst ->negotiated-> publish second track with simucalst
			// then the two media secontions have different rtp header extensions in offer
			if err := m.updateHeaderExtensionFromMediaSection(media); err != nil {
				return err
			}

			if !m.negotiateMultiCodecs || (typ != RTPCodecTypeAudio && typ != RTPCodecTypeVideo) {
				continue
			}
		}

		codecs, err := codecsFromMediaDescription(media)
		if err != nil {
			return err
		}

		addIfNew := func(existingCodecs []RTPCodecParameters, codec RTPCodecParameters) []RTPCodecParameters {
			found := false
			for _, existingCodec := range existingCodecs {
				if existingCodec.PayloadType == codec.PayloadType {
					found = true

					break
				}
			}

			if !found {
				existingCodecs = append(existingCodecs, codec)
			}

			return existingCodecs
		}

		exactMatches := make([]RTPCodecParameters, 0, len(codecs))
		partialMatches := make([]RTPCodecParameters, 0, len(codecs))