...

    session.createStream({
        name: streamName,
        display: localVideo,
        constraints: {video: true, audio: false}
        ...
    }).publish();

Audio only stream publishing

In most cases, it is enough to set the constraints to publish audio only stream:

    session.createStream({
        name: streamName,
        display: localVideo,
        constraints: {video: false, audio: true}
        ...
    }).publish();

Audio only stream publishing in Safari browser

When audio only stream is published from iOS Safari browser with constraints, browser does not send audio packets. To workaround this, a stream should be published with video, then video should be muted:

    session.createStream({
        name: streamName,
        display: localVideo,
        constraints: {video: true, audio: true}
        ...
    }).on(STREAM_STATUS.PUBLISHING, function (stream) {
        stream.muteVideo();
        ...
    }).publish();

In this case, iOS Safari browser will send emply video packets (blank screen) and audio packets.

Disable resolution constraints normalization in Safari browser

...