topic Re: Do virtual backgrounds increase bandwidth utilization? in Webex Meetings and Webex App

Do virtual backgrounds increase bandwidth utilization?

amoskraus — Tue, 20 Oct 2020 20:36:32 GMT

We've been using virtual backgrounds for a month or two now and I have had a few people say the performance of there video conference is impacted when they use a virtual background. I did some testing on my own and I didn't see an increase in bandwidth when adding a virtual background verse not using one. Video bandwidth seems to mainly be affected by the amount of movement.

We like the additional privacy that virtual backgrounds add, but I just want to make sure I understand if there any possible down sides to using virtual backgrounds. Any recommendations / feedback would be appreciated.

Thank you!

Re: Do virtual backgrounds increase bandwidth utilization?

Avinash Gaur — Wed, 21 Oct 2020 05:23:26 GMT

Hello @amoskraus ,

There is a hardware requirement for virtual background feature to work on Webex. Please see the link below:

https://help.webex.com/en-us/80jduab/Use-a-Virtual-Background-in-the-Cisco-Webex-Meetings-Suite#id_138414

Basically, the Virtual Background feature is CPU intensive, hence BU has provided these guidelines.

Also, please see the link below for minimum bandwidth requirements for sending and receiving video in a Webex meeting:

https://help.webex.com/en-us/WBX22158/What-are-the-Minimum-Bandwidth-Requirements-for-Sending-and-Receiving-Video-in-Cisco-Webex-Meetings

Thanks,

Avinash

Re: Do virtual backgrounds increase bandwidth utilization?

Fritz_H — Wed, 21 Oct 2020 08:47:59 GMT

@amoskraus
While analog filming meant to shoot 24 (or more) full-frame-pictures per second, modern digital Video-Compression-Algorithms ("Codecs") are working with just a few full frame images and visual changes.
Usually a Codec takes a full frame image and then saves just the visual changes of the following frames.
After some time another full frame image is taken and then again just the differences and so on.
As you noted, movement is such a visual change.

If the background of your VideoCall is e.g. a window showing a busy street or trees moving in the wind etc.. this will cause to Data-Rate to increase while a static background (wall, curtain etc.) or a static virtual background will not cause the Data-Rate to rise.
I also remember, that Cisco recently announced to have optimized the Video-Codec to provide more detail (= Data) for the Face-Area and use less bits and bytes for the background. (sorry, can not find the link to that announcement any more..)

Webex (and all other similar software-based tools) use an algorithm to recognize and differentiate between Person and Background. This will sometimes cause artefacts and semi-transparent body-parts.
You may "help" the Software by wearing clothes that have a very different color than the real (!) Background (since this is the data the algorithm is working with..) OR you may go pro and think about a green-screen-solution/chroma keying.
But since Webex does not yet (?) support this feature natively, this method will cause some changes in your setup and is also a bit far off-Topic.

Re: Do virtual backgrounds increase bandwidth utilization?

amoskraus — Wed, 21 Oct 2020 14:00:02 GMT

Thanks for your reply Fritz_H. This information is very helpful and helps confirm what I was thinking/seeing.