Frequenty Asked Questions

How can I join a session receive-only, without sending any media?

If you are using ion-sdk-js this should work by default. If not, read on.

If a participant does not have a microphone or camera, or denies access to them from the browser, how can they join? Something needs to be added to the publisher connection to generate valid SDP.

Add a datachannel to the publisher peer connection. e.g. this.publisher.createDataChannel("ion-sfu")

Does ion-sfu support audio level indication, telling me who is talking?

Yes. The subscriber peer connection will contain a data channel. It gets sent an array of stream id that are making noise, ordered loudest first.

Stream id is the msid from the SDP, defined here. It is up to your application to map that to a meaningful value, such as the user's name.

Here is an example in Typescript:

subscriber.ondatachannel = (e: RTCDataChannelEvent) => {
	e.channel.onmessage = (e: MessageEvent) => {
		this.mySpeakingCallback(JSON.parse(e.data));
	}
}

Audio level indication can be tuned here in the configuration file.

Can I record the audio and/or video to disk?

Recording (and general audio/video processing) is provided by separate project ion-avp.