A Look inside Citrix's New Technology

During Bob Kruger's (Citrix CTO) keynote presentation, Citrix's Director of Product Management Brian Nason demonstrated two new technologies: Multimedia streaming (codenamed “rave”) and JPG-based image compression.

At their recent iForum conference, Citrix demonstrated several new technologies that are going to be part of the new version of their MetaFrame Presentation Server product expected in the first half of next year. During Bob Kruger's (Citrix CTO) keynote presentation, Citrix's Director of Product Management Brian Nason demonstrated two new technologies: Multimedia streaming (codenamed “rave”) and JPG-based image compression.

I had a chance to sit down with Brian and ask him a few questions about the details of these two new technologies.

Multimedia Streaming via ICA

Citrix's “Rave” technology allows multimedia content to be streamed from a MetaFrame Presentation Server through an ICA session to an ICA client. Using this technology, the content is as sharp and crisp as ever, and CPU utilization on the server is lower than when content is streamed via the current version of MetaFrame. Citrix developed this technology after recognizing the increased business role that multimedia content is playing in today's corporate workplace.

To understand how this new technology works, it's important to understand how multimedia streaming works in current MetaFrame environments.

Traditionally, if you have multimedia content (a DivX video, for example) that you want to integrate with your MetaFrame servers, you install a media player and the appropriate codecs on your MetaFrame server. Your client devices need nothing more than the standard ICA client. When content is streamed from the server, the server's locally installed media player software uses its codec to decode the stream and pass it to the display. Terminal Server's MultiWin components intercept the display and audio data, and Citrix's server-side ICA components encode the data into an ICA stream. The content is sent to the client device as ICA data, and the client device's ICA software decodes the ICA stream and displays it on the screen.

Unfortunately, there are inefficiencies in this model that cause poor video quality, dropped frames, and choppy sound. First is the fact that ICA was designed to handle graphics associated with Windows applications—not multimedia content. The ICA protocol just can't handle the amount of data needed for watching videos. There are also scalability issues when watching videos via ICA , since the server must spend valuable processor time decoding the original content stream and then immediately re-encoding it for ICA .

Citrix's new “rave” technology completely changes this model. In this model, multimedia content is streamed to the client device via the ICA protocol in its originally encoded state . This means that the server does not have to spend processor time decoding and re-encoding the content. Also, since whatever format the content was originally in is probably more appropriate for streaming content than ICA , the content can be sent to the client device in the most efficient way possible. This means that a client device can watch videos from a MetaFrame Presentation Server at full quality.

The ramifications of this architecture are that the client device must have a media player and the appropriate codes installed locally in order to view a content stream from the server. In today's world, however, this is not usually a problem. Even so called “thin” devices have local processing capabilities, and media players are available for all operating systems, including Windows CE and Linux.

So what's the point of this if a local media player is needed on the client? Citrix is not trying to make streaming content any better than it is without MetaFrame. The “rave” technology simply allows MetaFrame Presentation Servers to provide multimedia content to client devices in addition to traditional Windows applications. As their new marketing message states, they're striving to provide the “access infrastructure” that supports whatever a user needs to access—be it multimedia content or Windows applications.

Lossy Compression

Another upcoming technology that Citrix showed off at iForum was a JPG-based compression technology that allows certain images to load much faster on client devices. Brian Nason led a very powerful demonstration where he had two client devices side-by-side, one with the new technology and one without. He simultaneously opened a photo-laden Word document from both client sessions, and the images popped into the session with this new compression technology in about 1/10 th the time as they did in the other session.

When I spoke with Nason, my question was simple: “How does it work?”

Nason explained that traditionally, Citrix has focused on “lossless” compression. In current versions of MetaFrame Presentation Server, screen data on the client device is a pixel-for-pixel, 100% exact match to the source data on the server. While the ICA components of MetaFrame do compress the data, the lossless requirement effectively limits the amount of compression that can be applied.

In the new MetaFrame Presentation Server technologies, Citrix will give administrators the option of enabling “lossy” compression. Lossy compression will allow for much greater compression ratios because the software on the client device will interpolate some of the pixel information based on compression algorithms.

In the real world, lossy compression is used everyday without anyone noticing. The different types of compression are the fundamental differences between bitmap files (lossless) and JPEG files (lossy). This is why a 3MB bitmap image can be “saved as” a JPG file that's only 200KB. The sophisticated compression algorithms mean that in most cases, people won't be able to see any difference between the two images.

Of course it's important to note that the lossy compression capabilities of the new version of MetaFrame will be able to be turned on an off, which is a good thing if you were using MetaFrame to serve something like a medical imaging application.

All in all, these two new technologies are only a small subset of what Citrix has on tap for their new version of MetaFrame Presentation Server. I'll keep you posted on the inner workings of all the new capabilities over the next few months.

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This message was originally posted by an anonymous visitor on October 23, 2004
This article contained critical information for us since we are deploying a medical imaging app on a Citrix Metaframe server
We presently are running Metaframe XP and the radiology images the doc's need to view are not acceptable.
We are going to upgrade to 4.0 in the near future and were wondering, are the images going to be better
with 4.0?
Not acceptible how?  Too slow to render, not high enough color depth...  I work in an Orthopedic Clinic, so I am also interested in this for MRI, CT, X-Ray...

We presently are running Metaframe XP and the radiology images the doc's need to view are not acceptable.
We are going to upgrade to 4.0 in the near future and were wondering, are the images going to be better
with 4.0?

The images on not clear but I found out that the differences in individual video cards is the problem
Talked to a radiology person and he says they look fine on his machine but not on his co-workers.
That is where the individual video problem comes in. (not a citrix issue)
Also, the doc's are saying when they get on from home, the images are too slow.
Thanks for the reply!
If speedscreen is enabled, images would be compressed, decreasing their quality.  24 or 32 bit color may be a requirement.
From my home computer, I can flip thru large images pretty quickly, but never as fast as viewing them on a medical imaging workstation where you could page flip thru a multi-slice CT in a few seconds
So, do you think there is an improvement in 4.0 in viewing these images?
Compared to what?
We have speed screen enabled and we are running metaframe xpe 1.0.
When we pull up a CT image with approx 80 frames, there is about a half second lag in between each
frame. When we use the picom "Simage" (vendor)  client thru IE, the image does not have a lag.
So I am asking if it is improved with 4.0 or are you saying we should not be seeing that issue today?
By what you asked already, I would think this would fall under a rendering catagory?
I could probably explain better on a 5 minute call perhaps if you have the time.
You may want to contact this person at Citrix about this:

A little while ago, you participated in a Citrix Graphics Application Survey posted on the Citrix Developer’s Network site. This email is in response to your indication that you would be willing to discuss requirements/needs you have as it pertains to graphic intensive applications and Presentation Server with Product Management.

I’d like to set up a conference call with yourself and other participants from your company to discuss your business needs, any pain points you have with deploying graphic intensive applications, market size, etc… This is simply an information gathering session for supporting these OpenGL types of applications, I will not be trying to sell anything. It is an opportunity for your company to influence the future development at Citrix.
If you would please let me know if you would still be willing to have this discussion, we can set up a conference call. I look forward to speaking with you.
Debbie Fox
External (954)229-6111
Internal x.26111, Spectrum Office #1041