09-13-2022 03:26 AM - edited 08-09-2023 03:40 AM
Hi community
Edit, August 2023
Since CMS 3.7.1 the presentation quality is acceptable and they've added more options to adjust it in CMS 3.7.2.
However the suspected, yet unconfirmed, cause (see here) for the once very bad presentation quality persists in CMS 3.7.2.
Observed behavior (MS Edge, Chrome):
Example of the problem:
Any technical suggestions what we could be looking at here? It always draws that kind of pattern where the lower part of the image seems to be turned into those huge square pixels.
I kind of suspect QoS issues/misconfiguration but have a somewhat hard time to proof it to the network team. When joining the meeting through a smartphone (cellular network) the presentation looks crisp again.
Another thing that would be helpful for educational purposes @people that have CMS running and can do presentations smoothly:
Would you be willing to open edge://webrtc-internals/ during an ongoing meeting and take a screenshot of the various graphs (incoming RTP stream of the presentation)? I'd be curious how some "good" reference stats of a smooth presentation should look like.
Below is what it looks like in our setup when I share a simple Excel sheet in a presentation and scroll around in it a bit. On the receiving end the grid of the cells is gone most of the time and it just kind of looks like a pixelated, laggy, blurry soup. When I stop scrolling it takes 2-3 seconds until quality is adjusted. Interestingly with MS Teams presentations work flawlessly (I mention it because I think both are based on WebRTC technology when using the browser).
Anyone else ever experienced similar issues? And got it fixed? Any feedback / suggestions are welcome.
Best regards
Dave
06-02-2023 06:06 AM
Just wanted to bump this with an update.
CMS Presentation quality still bad
By now we suspect that the clients themselves / the browser might be the bottleneck. Since Zoom, MS Teams, Jitsi are all working fine we're kind of lost and out of ideas. Idea donations about what we could investigate or how we could tackle the bad presentation quality would still be welcome.
Cheers,
Dave
06-18-2023 06:56 AM
We also upgraded to the latest version of 3.7 and the issue existing , what will be the next step?
06-29-2023 01:10 AM
We have the same problem. There are moments that it is fine and after a while the ping increases and everything blurs. We tried everything.
07-14-2023 08:32 AM
We are having the same problem. I agree that it appears that the client (browser) is the bottleneck, but not entirely sure why.
Anyone have any ideas?
07-14-2023 11:13 AM
in version 3.7.1 it's much better. Unfortunately, after locking the presentation to 720p, the presentation mode is blurry. Try this update!
07-14-2023 11:25 AM
Are you referring to the callLegProfile settings for qualityPresentation in the API? What about if you set the presentation to "unrestricted" or "max1080p30"?
07-14-2023 11:43 AM
In version 3.7.1 cisco locked presentation resoluton to 720p.
and when u look to api guide. This is note to qualityPresentation
Note: This parameter does not apply to
incoming video from Cisco Meeting App or
Cisco Meeting App WebRTC app.
You can set what u want and presentation quality still stay 720p.
07-14-2023 12:17 PM
So there is no way to change that presentation setting that Cisco has locked? I wonder if there is a command in the API that you can change that setting. Has anyone else tried this?
07-14-2023 12:43 PM
I think it works but only in SIP connection
07-14-2023 01:35 PM
We haven't seen too many issues from SIP endpoints. Where we see the problem is from participants coming from the browser, just as the OP mentioned above.
Are there ways to test/monitor the WebRTC connections to see if that is indeed where the bottleneck is coming from?
07-24-2023 05:57 AM - edited 07-25-2023 03:49 AM
Edit
tl;dr: Could the lack of AV1 codec support in CMS be the reason for the bad presentation quality during screen sharing?
Edit 2:
Did a quick test with Microsoft Teams. Shared screen and checked what codec is used. In my setup it was h.264, no macroblocking observed, despite Teams servers not even running here on-prem. Repeat same setup with CMS and there's macroblocking and incredible rubberbanding for the audience everywhere (presentation is lagging behind more and more over time and at some point they get confused about what I'm talking about as their slides are lagging 5sec or so behind). I'm lost. No clue where things might go wrong with screen sharing in CMS and out of ideas how to contribute to a solution.
----------------------
Unfortunately can't provide a solution but at least a better problem definition.
Came across this FAQ where screen resoultion of sender and receiver is mentioned as factor in presentation quality. There are some other interesting things mentioned as well that lead down a deep rabbit hole.
6. Minimize the difference between the presentation sender desktop resolution and the receivers’ desktop resolution
The difference between the presentation sender’s resolution and receiver’s resolution is very important. If the sender is sending its desktop at 4K resolution (8M pixels) but the receiver is only receiving at 720p (0.9M pixels), the presentation video will be scaled down to 1/8 of its original size and this is likely to cause significant softening of the picture, any text will likely to be completely unreadable. On the other hand, if the sender is presentation at 1080p and the receiver is receiving in 1080p full-screen, then there will be no degradation due to downscaling.
By default, the receiving WebRTC app will show both main video and presentation in a stacked layout. To improve sharpness of the content in the presentation video, it is recommend switching to the “presentation only” layout on your app, as it will make the best use of your browser tab’s viewing size.
7. Avoid transition effects, animations and fast movements in presentation content
Transition effects and animations on desktop (such as Windows Aero effects) or in applications (such as PowerPoint) should be minimized or avoided to improve the overall experience on the receiver. This is due the fact that fast movements are not optimized for the sharpness-focused presentation video. In extreme cases sharing a video stream within the presentation video will have significant framerate drops and macroblocking (1). This is due to how the H.264 video codec is used in real-time communication scenarios.
Within the cisco community you can only find 3 postings that mention macroblocks. Even on google or youtube you don't find a whole lot about the topic which has its roots somewhere deep in the realm of video codecs. Looking at the screenshot of our problem it sure does look an awful lot like we're experiencing some sort of macroblocking issues with CMS webbridge while sharing the screen.
Structures defined by the H.264/AVC standard.
(1) Macroblocking
Video content that contains large IFrames can cause macroblocking during playback on SV-4K and DMP-2K media players. Macroblocking is a video artifact where areas of a video image appear as small blocks or squares.
Release 4.1 and Later Releases: Cisco StadiumVision Content Creation Design and Specifications Guide
Macroblocking demo video by SSIMWAVE (R) can be found on youtube.
Macroblocking example, (c) ssimwave.com
In this community posting here @Mohammed al Baqari is taking a deep dive into