How to modify SDP before setting local description?

[fragrant corn]

Hi!

I want to know how to modify SDP before setting local description. 

After create offer, can i get the body, modify it and then set to local description? 

What API should i use?

Thank you!

[Vikas]

Hi,

You should take a look at pc1 demo source. Basically when you call createOffer api, you get a callback with sessiondescription. For e,g, In below code gotdescription1 is the callback function & desc.sdp is the sdp that you can modify before calling SetLocalDescription.:-

pc1.createOffer(gotDescription1);

function gotDescription1(desc){

  pc1.setLocalDescription(desc);

  trace("Offer from pc1 \n" + desc.sdp);

  pc2.setRemoteDescription(desc);

  // Since the "remote" side has no media stream we need

  // to pass in the right constraints in order for it to

  // accept the incoming offer of audio and video.

  pc2.createAnswer(gotDescription2, null, sdpConstraints);

}

/Vikas

[fragrant corn]

Hi, thank you for your help.

Besides what you have provided, i also have a doubt.

Since desc.sdp is not structurized, it is very easy to make mistakes when modify the value of desc.sdp. I want to know what method is best if i want to change "a=sendrecv" to "a:recvonly".

[fragrant corn]

Hi, thank you for your help.

I want to modify desc.sdp, but since the value of it belongs to no data struct, when modifying it (for example change a:sendrecv to a:recvonly), it is easy to make mistakes. So i want to know is there any proper API or method i can use to modify it.

[Vikas]

Hi,

You can use the replace method. Something like below:

desc.sdp = desc.sdp.replace(/a=sendrecv/g, "a=recvonly");

/Vikas