How to both audio and video call to audio only?

[MCCM Yu]

Hi,

As a WebRTC gateway,  RtpEngine works on video+audio call.

And when I change media to video+audio from only audio, It works with command `offer`.

But I tried to change media to only audio from video+audio via renegotiation with calling command `offer`,

RtpEngine responses SDP still has video media.

In this case, How can I change media to only audio?

[Richard Fuchs]

I'm guessing your first offer/answer has two `m=` lines, and you're
trying to set it to audio only by making another offer with just one
`m=` line?

According to the RFC (3264), an updated session description must have
the same number of `m=` lines as the previous one, or more. It's not
allowed to simply remove a media section.

So the correct way to remove a media section is to leave it in place but
set the port to zero. Alternatively you can leave it intact entirely but
flag it as `a=inactive`.

Cheers