Thank you Kevin.

Any idea if Google developers may decide to reset the decoder, per Joshua’s 
experience?
Or perhaps asterisk developers would consider eventually add the rewrite 
support in asterisk?

Always fun dealing with newer technology as it goes through several revisions.

Have a great day!

Dan

From: asterisk-users <[email protected]> On Behalf Of 
Kevin Harwell
Sent: Thursday, March 14, 2019 4:50 PM
To: Asterisk Users Mailing List - Non-Commercial Discussion 
<[email protected]>
Subject: Re: [asterisk-users] Does anyone know if there is a problem with the 
Chrome browser and asterisk cmp2k video

On Wed, Mar 13, 2019 at 10:15 AM Dan Cropp 
<[email protected]<mailto:[email protected]>> 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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