Telestream's ClipMail Pro is a system for sending video and audio over any standard data network, including the Internet, to destinations anywhere in the world. An optional control panel has a touch screen that provides simple user control of almost all ClipMail Pro functions and displays live video so the user may preview a video before sending it.

To create the touch screen, Telestream designers needed a tool that would allow them to create a highly customized graphical user interface (GUI). The tool also had to be highly portable, allowing them to design for a real-time OS, and it had to allow painless writing of drivers for devices that do not use the VGA standard. Telestream looked at the options available and chose Zinc for VxWorks from Wind River Systems.

In the not-so-distant past, sending a video from, say, New York to Shanghai involved dubbing a copy from the original, packaging it, and posting it with an air courier service. If you were lucky, the tape would arrive at its destination the next day. If you were not lucky, it would arrive days late or not at all, and bad luck was not that unusual.

Currently audio and video can be transmitted over the Internet using what is called "streaming technology." But in streaming technology quality and bandwidth are mutually dependent. That is, the higher the quality, the higher the bandwidth requirement, so if you are using a pipeline with limited bandwidth, quality is compromised, making the method unsuitable for transmitting high-quality material such as you would use in corporate training videos, commercials, or broadcast.

In response to the need for faster, more reliable, and more cost-effective means of transmitting video and audio around the world, Telestream created ClipMail Pro, a system that allows transmission of even broadcast- and digital-master-level video and audio over low-bandwidth pipelines with no compromise in quality. Audio and video content can be delivered in minutes to any LAN or WAN in the world, whether it’s T1, E1, J1, ISDN, DSL or DS3. MPEG-2 compression and store-and-forward technology preserve sender-selected quality, from the lowest to the most demanding requirements for making a digital master, at the highest speed the network supports -- which is not possible with standard streaming technology.

Telestream is located in Nevada City, California -- one of the world's top five video technology centers. The business was established in early 1998, and now has forty employees. ClipMail Pro is its first product, introduced at the National Association of Broadcasters show in April 1999.

ClipMail Pro is housed in a chassis about three inches wider and deeper than a VCR. On the back are connections for just about any kind of professional video and audio gear, either digital or audio. A 10/100Base-T connector is on the front.

Operation is simple: interacting with the system using an external monitor or a Telestream control panel, the user selects or enters the address of a recipient, digitizes and stores the video/audio material at the desired quality on the system’s internal hard disk, then sends it out over the chosen connection as fast as the available network will carry it.

How the touch screen works

When the system is booted up, a Send screen appears. The screen displays four text boxes for entry of the media parcel name, the address of recipient, a cover page message, and the selected clip to send. If a keyboard and mouse are attached, the user may enter text in these boxes just as you do with a computer. If there is no keyboard and mouse, any of the text boxes are selected simply by touch. A cursor then appears in the box and a virtual keyboard appears on screen. The user enters text by touching the keys of the virtual keyboard.

There are also seven buttons on the screen: Send Mail, Check Mail (to see contents of the In Box), Setup, Clear All (to clear all selections in the text boxes), Save, and Send. These buttons are activated by touching them.

Several other screens supplement the Send screen. For example, pressing the Setup button opens a screen with Rolodex-type tabs for entering or viewing addresses, and for selection of various video and audio types and standards, network settings, and other variables. A Make Clip screen displays video and plays audio from a VTR and allows selection and digitizing of a clip.

Zinc for VxWorks fills the bill

Telestream chose Zinc for VxWorks to create its touch screen because it provides a complete object-oriented, C++ application program interface (API) for the creation of graphical user interfaces and event-driven applications, and makes it possible to create sophisticated user interfaces by means of a wide range of user interface objects – from windows and buttons to notebooks and tables.

A touch screen requires a look that is appealing and that people will enjoy using. It's quite a different "feel" from a keyboard and mouse-controlled system. With Zinc, any user interface object may easily be customized to deliver a unique appearance and feel; it can also emulate any popular desktop style, if desired.

Shawn Carnahan, Chief Technical Officer at Telestream, says, "Since Zinc is C++ based, it was very easy for us to subclass the existing UI elements and create new types of buttons and sliders that are more appropriate to a touch screen interface than those you would use for a mouse/keyboard interface."

Telestream also chose Zinc for VxWorks because it fulfills the graphical requirements of embedded computers for building a rich, full-scale embeddable GUI with low system overhead. Zinc is composed of GUI libraries, a visual design tool, portable make utility, hypertext-based on-line documentation, and numerous examples and tutorials. It can easily be scaled and configured to meet the exact GUI requirements of a given application. Designed for memory-constrained environments, Zinc for VxWorks can fit a complete configuration consisting of VxWorks and Zinc libraries in less than 1MB of memory. "We wanted a small memory footprint," says Carnahan.

Telestream also needed a tool that was highly portable. ClipMail Pro was not designed as a PC platform with a traditional VGA monitor, and so the GUI tool had to support a high degree of customization. Carnahan explains, "An embedded application requires a different set of class kits from a PC or Mac environment where you've already got access to a front end. We needed something that was highly portable in terms of how it would interact with our hardware frame buffers. We used the TriMedia TM-1100 chip from Philips Semiconductors as the display controller, so we needed a generic frame buffer where we could write our own driver.

"Since we're not using standard VGA cards, we needed to write our own drivers for the graphics interface. In addition, we needed to design it to operate without a keyboard or mouse, and to integrate slow-motion video into the interface. Since Zinc comes with a lot of drivers that are well-documented, and the interfaces are clearly defined, it was easy to subclass the existing display drivers with our own specific ones. Zinc was also more portable than the others we looked at, and it was the first choice of the people who do the coding. Overall we were very very pleased."

For their RTOS, Telestream chose VxWorks, partly because it is so popular that there's a large base of engineering talent available that is familiar with it. "I can make two phone calls and have people in here right away with ten years of VxWorks experience, people who already know how to use an embedded OS. Also, because VxWorks is so widely used, it's easy to get third-party code. We used Tornado tools in development, too.

All in all, Carnahan says, "We're big fans of VxWorks and Zinc."