Javascript WebRTC-如何区分通过同一连接发送的两个MediaStreamTrack？

我想使用WebRTC将两个视频流从Peer1发送到Peer2：以前后摄像头为例

从概念上讲，Peer2如何知道哪个流来自哪个摄像头

提到所有的

MediaStream

和

MediaStreamTrack

字段都是只读的，所以我不能直接向它们附加任何信息。我不能通过信令通道发送像

{“stream1 id”：“camera”，“stream2 id”：“screenshare”}

这样的字典，因为Peer2将为每个流和磁道生成自己的id。

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因此，在浏览器支持自定义

msid

之前，似乎无法完成此操作。

msid已经受支持-只需读取发送方上每个流的

msid

，然后通过您提到的信令通道发送它们。@xdumaine哪里有msid可用？我不认为它是作为getUserMedia结果创建的流的属性。

In the RTP specification, media streams are identified using the SSRC
field.  Streams are grouped into RTP Sessions, and also carry a
CNAME.  Neither CNAME nor RTP session correspond to a MediaStream.
Therefore, the association of an RTP media stream to MediaStreams
need to be explicitly signaled.

WebRTC defines a mapping (documented in [I-D.ietf-rtcweb-jsep]) where
one SDP media description is used to describe each MediaStreamTrack,
and the BUNDLE mechanism [I-D.ietf-mmusic-sdp-bundle-negotiation] is
used to group MediaStreamTracks into RTP sessions.  Therefore, the
need is to specify the ID of a MediaStreamTrack and its associated
MediaStream for each media description, which can be accomplished
with a media-level SDP attribute.

This document defines a new SDP [RFC4566] media-level "msid"
attribute.  This new attribute allows endpoints to associate RTP
media streams that are described in different media descriptions with
the same MediaStreams as defined in [W3C.WD-webrtc-20150210]., and to
carry an identifier for each MediaStreamTrack in its "appdata" field.