SX20/80-based endpoints on CE9.x - main video & presentation resolutions/frame rates at different call rates?

[cmackOTI]

Hi all,

I'm looking for an extension of the call speed documentation contained in the SX80 CE9.2 admin guide, specifically to the table "Adjust the video quality to call rate ratio (page 2 of 2)" on page 41.

The table lists the various call rates, and gives the main video resolution and frame rate achieved with each optimal definition profile (Normal, Medium, High).

Does a table exist which gives the main video resolution and presentation resolution at various call rates?

For example, I can create a 768kbps call at the Medium profile, and end up with 720p30 main video, which is what's specified in the table. If I then start a presentation:

• Main video drops to w448p30, which is the main video resolution achievable at half the call rate at equal main/presentation weight, i.e., 384k/Medium; and,
• The presentation channel transmits at 1080p2, which I presume is what is achievable at 384k with the input set to Sharpness.

If I want to increase the call rate to provide better main video and/or presentation resolution, what is the outcome at various higher call speeds? For example, if I raise the call rate to 1536kbps/Medium, I presume that a video only call will still be 720p30, per the existing table, but what happens when I start a presentation? Does main video stay at 720p30 (half of 1536k = 768k, then refer to table)? Do I get 1080p5 for the presentation from the other 768k? Something else? What's the benefit of raising the rate to 2176kbps? Etc., etc.

I would love to just go and try out the combinations myself, but I would need to raise a change to do it... Plus, this should be documented somewhere, right?

Thanks for your help.

Cheers,

Callum.

[Patrick Sparkman]

The resolution in the tables apply to both main video and content, if you want both video channels to be 720p, you'll need to connect a call rate that has enough bandwidth to support both at that resolution. For example, 720p with a profile of Medium requires 768kbps, which means no less than a 1536kpbs call rate for both main video and content to support that resolution. If there is any remaining bandwidth, I believe it can be used to increase one or both of the video channels depending on which one that might need it.
Using a higher the call rate will allow the endpoint to send/recieve higher resolutions for both main video and content, but this is also dependent on the call rate and capabilities of the other connected endpoint or system.
What's in the endpoint admin guides is the only documentation.

[Wayne DeNardi]

In addition to what @Patrick Sparkman has written, which is a very good explanation, there was the ability in the older software releases (TC7.x and CE8.x) to add weightings so that bandwidth could be skewed one way or the other between the main video and the presentation rather than the default 50/50 - so with that, there was no 100% accurate answer as to what the actual numbers would be as they could be altered with a number of settings, and hence why you won't find specifics documented anywhere.

The VideoBandwidth Weight settings are no longer available in CE9 though, so this behaviour is no longer able to be controlled as was possible in the earlier software releases.

If you have a good case for it, you could send a Feature Request through your local Cisco Account Manager back to the development teams to be (re)considered for a future software release (I believe CE9 was a complete re-write of the code from TC7/CE8, hence why some of the older functions are missing, but many are making a slow return as requested through these Feature Request submissions).

[Joel Stanfield]

What is the effect of setting the content connector OptimalDefinition Profile setting different than the video connector? It would seem that any computer signal would be fine at the High setting, then would the bandwidth used be less or the frame rate higher?

[Patrick Sparkman]

Each input into the codec has their open optimal definition profile, so you're able to adjust how much bandwidth is needed to achieve a certain resolution. If you only care about getting the highest possible resolution for content and not main video for example, you can choose to only adjust the profile for the content's input.
The recommended setting is either Normal or Medium, but High can be used if the lighting conditions are good. However, since we're talking about content and not a camera input, no need to consider lighting an issue. So yes, computers should be able to benefit from the High profile option, thought I haven't tested it out myself to see the results.
If set to High, the bandwidth required for higher resolutions would be reduced, but it will not increase frame rate. Frame rate is determined by Video Input Source Quality, the two options are sharpness and motion. Sharpness will give you the highest possible resolution at the cost of low frame rates, while motion will give you the highest possible frame rate at the cost of lower resolution.

[Joel Stanfield]

Thanks for the quick response. 

A followup question; what would be the consequence of setting the main video profile to High, in terms of the image quality? Assume the camera is a Cisco model, Quality set to Motion and FPS at 30. What aspects would likely be degraded verses a Medium profile setting, if the room lighting was not optimal (bright enough or uniform)?

[Wayne DeNardi]

The "quality" will depend largely on what the camera is capturing, and whether it's a relatively still image, or fast motion.

The main impact will be the amount of bandwidth used for the resolution you want.  There is a good table on page 41 of the SX80 CE9.2 Admin Guide.