[asterisk-users] Does anyone know if there is a problem with the Chrome browser and asterisk cmp2k video

Kevin Harwell kharwell at digium.com
Thu Mar 14 16:50:23 CDT 2019

On Wed, Mar 13, 2019 at 10:15 AM Dan Cropp <dan at amtelco.com> wrote:

> Using asterisk 16.1.1.
> I’m setting up a test using the cmp2k (Cyber Mega Phone 2K Ultimate
> Dynamic Edition).
> I have noticed Chrome 72 had some issues with video streams.  I just
> upgraded to Chrome 73 and see they still have some issues.  If I have 2
> calls in a confbridge with video set to none.  I then set the video source
> to a Chrome browser and the Remote Video shown to both calls from Firefox
> and Chrome do not update.  However, if I set the video source to the
> Firefox browser, my Remote Video is accurate in both Firefox and Chrome.
> I confirmed that asterisk is indicating the video source changed by
> looking at the AMI BridgeVideoSourceUpdate event.
> When I use the Firefox (65.0.2) browser I can set either call to be the
> video source and the Remote Video updates accordingly.
> Is this caused by Chrome’s video sent to asterisk being some format which
> asterisk can’t use in the confbridge?

The way I understand it is that video stream has changed, so the browser
needs some way to know that. Otherwise the decoder thinks it's invalid data
and drops it. In these cases either Asterisk needs to issue a renegotiation
(currently not supported), or the codec needs to contain video stream
information in their payload. I spoke with Joshua Colp about this some as
he's had some dealings with this and he had the following to say:

"Some codecs (such as VP8/V9) embed information about the video stream
within their payload. Asterisk does not currently rewrite this information,
so when a stream change occurs in Asterisk using the selective source
functionality this can cause the receiving side (the browser) to drop the
payload as it sees it as not being part of the existing stream. Different
browsers can behave differently, such as resetting the video decoder to handle
the new stream. Rewriting this information in the video payload is not
currently supported."

So you are probably seeing it work or not in Chrome vs Firefox due to
browser, and codec support of such occurrences.

   .... <snip config> ....

Kevin Harwell
Digium - A Sangoma Company | Senior Software Developer
445 Jan Davis Drive NW - Huntsville, AL 35806 - US
Check us out at: https://digium.com & https://asterisk.org
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