Bug 187227 – Cloned MediaStream audio attached to peer connection causes local echo

• Status: RESOLVED
• Resolution: INVALID
• Component: WebRTC

[Chad Phillips]

1. Peer connection with inbound/outbound audio/video stream attached to a video element
2. Clone the stream to re-use on another peer connection, and attach to other audio/video elements
3. Hide the first video element

This results in a local echo coming from the user's own microphone, not from any inbound audio.

What's really weird is that if I display the first video element again, the echo goes away and doesn't return.

[Radar WebKit Bug Importer]

<rdar://problem/41704722>

[youenn fablet]

Thanks for the report, would you be able to provide a jsfiddle or something like that so that we can easily reproduce the issue?

[Chad Phillips]

Still trying to find a simple way to reproduce this issue for testing.

In the process I believe I at least found why the echo stops if I display the first video stream again.

As a simple demonstration, I recorded the issue, viewable here: https://youtu.be/eVQVSy6Edt8

The first playing video is a peer connection that's also sending local audio/video to a conferencing application. When I start a second peer connection that also has local audio/video, you'll see that the first video stops (audio stops too).

This doesn't seem to accord with the rules listed at https://webkit.org/blog/7763/a-closer-look-into-webrtc/, which say "MediaStream-backed media will autoplay if the web page is already playing audio", so I'm wondering if another bug is in order here?

[Chad Phillips]

This turned out to be audio playing from a video element with a local stream attached. Setting the mute property on the local video element solved the issue.