Streaming video lag on Cisco Telepresence Unit

[Yangjp715]

Hi all,

We used a Cisco MX300 to dial into our video bridge (CMS) for our town hall meeting and shared a streaming video through the whole process. However, we got some complains from branches regarding the video quality. The streaming video has buffering lag on their end. The switch port that VC unit connected has QoS configured and no more traffic on the WAN link at that time. Is there any way to improve the video quality? The shared video on a VC unit is video in QoS or data?

I tried to share a video in a WebEx session, even getting worse.

Thanks in advance!

[PJMack]

What's the call rate? higher will be better. The input you're using for the stream, is the "quality" set for motion, or sharpness? By default it's sharpness, you should set it to motion if you're sending video. You also might want to change the presentation channel weight, by default it's 50%. Another (perhaps the best) option would be to send the video as your main video rather than a presentation channel - when you're ready to start the video, just change the main video source from camera to PC or whatever you're plugged into, then switch back when it's done. 

[Yangjp715]

Question here, the DefaultMailSource is 3 that pointing to Connector 3 (Desktop)? The resolution needs to be changed? Thanks!

[PJMack]

You can't set the resolution, what resolution you will get will depend on what the quality is set to, how much bandwidth is available, etc. So in your case you have it set to favor motion (which is good), that means the codec will use a lower resolution and a higher frame rate than if you chose sharpness. What resolution that ends up being then depends on available bandwidth. For example, if you're doing your calls at 768K and the presentation channel weight is set to 5 (default), that means you only have 384K for the presentation, not nearly enough for HD at 30FPS.

The Threshold60FPS option that you highlighted is unlikely to come into play here, that is a setting that to state that you'll stay at 30 FPS maximum up until 1080p, and only then will it attempt 60 fps if there is sufficient bandwidth to do so. Based on your initial question I think it's safe to say there isn't. 

[Yangjp715]

Do i still need to change "RelayQuality" to Motion and "PresentationChanel Weight" to 5 or above under Conference menu? The maximum transmit call rate is 6M.

[Wayne DeNardi]

You say you have the max call transmit rate set to 6Mb, but what call rate was the call made at (what is your default call rate - what does your infrastrucure support, or does that apply per call or per link bandwidth limts)?  It's the actualy call rate of the call that you will need to increase which will use more bandwidth, and allow you greater resolutions and frame rates.

[Yangjp715]

Thanks Wayne, the default call rate is 6Mb for MX300. I did a test on a DX80. The existing settings as the following.

1. The default SIP call rate is 3072Kb

2. PresentationChannel Weight is set to 8

3. The streaming video is from Connector 2:

    a. Quality is set to Motion

    b. The resolution of the output for Connetor 2 is set to 1920x1080 60 FPS

The exact call rate is 1920 kb, Channel rate for presentation is 1004 kb and the receive is 27kb. It looks the video still had buffering lag. We are using CMS as video bridge. Is there anything i need to check in CMS?

[PJMack]

The default BW is irrelevant, you are calling at 1920, and you have the presentation weight set to 8, so your BW for the content BW is 1 GB. 1 GB is not enough BW for 1080/30. 

I've run into this before - my recommendation is to send your video content as primary video, not a separate content channel. If the meeting participants are watching the video, they won't care about the people in those rooms for those minutes, then you should get full motion video to everyone (including Webex participants - they will probably just want to go full screen). It will be a better experience than what you're trying to do - the video will never look good to the Webex clients over the content channel even if you crank up the bandwidth to make it OK in the video rooms. 

try it - I think you'll see it's the best solution for your situation