- From: Justin Uberti <juberti@google.com>
- Date: Wed, 15 Apr 2015 18:57:23 -0700
- To: Peter Thatcher <pthatcher@google.com>
- Cc: Martin Thomson <martin.thomson@gmail.com>, Harald Alvestrand <harald@alvestrand.no>, "public-webrtc@w3.org" <public-webrtc@w3.org>
- Message-ID: <CAOJ7v-22+5GMRLYYEQmsS5U-mqdVUBxma4=pgaNgBcjNXzgzew@mail.gmail.com>
The two arguments (that I know of) against using mid by itself: 1) addTrack followed by removeTrack followed by addTrack will result in the same mid for the second track, due to the quirks of SDP. This means that sometimes addTrack gives you a new mid, sometimes it won't. This is unfortunate, although if we wanted to go down this path, we could prohibit recycling m= sections without a corresponding mid change. IOW, you could only recycle rejected m= sections, and so the example here would result in two m= lines. 2) without a=msid, there is no way to detect a recyclable m= line (currently we can look for a=msid to determine this). Specifically, if you have a remote description without a=msid in a m= section, and you stop your local track for that m= section, you don't know whether to set port 0 (i.e. dead m= section) or not in subsequent offers, because you can't tell if the remote side is still using that m= section. On Wed, Apr 15, 2015 at 5:12 PM, Peter Thatcher <pthatcher@google.com> wrote: > Ah, I see. It's true that if we didn't allow JS to choose the value, it > would be the same as now where the JS cannot choose the track ID. So we > wouldn't be losing anything compared to the status quo. > > But isn't the JS always able to set it anyway via SDP munging? > > On Wed, Apr 15, 2015 at 3:24 PM, Martin Thomson <martin.thomson@gmail.com> > wrote: > >> On 15 April 2015 at 15:19, Peter Thatcher <pthatcher@google.com> wrote: >> > And te question isn't whether to allow the JS to choose the MID. It's >> > whether to have two IDs/labels (MID + something else), or just one >> (MID). >> > If one will work, I prefer one. >> >> >> Like I said, I am OK with just one and with that one being a=mid; I >> was pushing back at your suggestion that we let the JS set it, that's >> all. >> > >
Received on Thursday, 16 April 2015 01:58:11 UTC