Stream Labs.’s video cards

By Alexey Mayorov

Review contents:

CGs yesterday, today and tomorrow Software and hardware tools for TV programs graphic branding Graphic tools of DMS module system The use of XDR2-GENSEC in the systems of regional air branding Akula VTM video compositing system. New model range — new features Profitt’s titling and air branding systems, clock and logo generators Overview of the systems based on extended version of Alpha Pro software X-CG character generator — good choice for titles creation TitleBox graphic manager Clock Station Leitch’s equipment for air branding Matrox InfonetTV Deko CGs from Pinnacle Systems Company Pixel Power equipment Stream Labs.’s video cards Videoprinter system for DSC video switchers Videonics titling machines

Stream Labs. Company more than 10 years works on development and manufacturing of devices for TV. During last five years the main attention was paid to the devices dedicated to operation with SDI signal. First of these devices was demonstrated at TRBE’98 exhibition. Till present moment keeping in mind TV equipment market situation Stream Labs. Company has developed Stream Alpha series devices which features enhanced technical parameters and wide functional possibilities.

It is clear that single article doesn’t allow describe all characteristics of these devices that is why here is just brief description of the principal new features of Stream Alpha SDI, Stream Alpha Component and Stream Alpha Plus video cards and Stream Logo SDI logo generator.

Most sufficient changes gained Stream Alpha SDI card. It got maximum number of new solutions some of which than also migrated to other video cards and devices being developed by Stream Labs. Company for other fields of use.

Let’s note that new features described related first of all to hardware part and don’t get software support immediately. But awareness of end users of all possibilities and working modes of video cards can push the programmers to appropriate activity. Alpha Pro and VideoGrapher software applications bundled with these cards are being constantly enhanced exactly this way.

So, new Stream Alpha SDI has become multifunctional video card able replacing several devices at once. Beside its main function of graphics overlay onto SDI passing through signal or just output it to external video mixer the video card can do conversions between analog and digital (SDI) video signals. Moreover Stream Alpha SDI is able to realize functions of capture device for both stills and video sequences lossless and in real time.

Let’s look at these functions and to modules and block of video cards themselves.

Inputs and outputs

Stream Alpha SDI

Stream Alpha SDI video card works with 8- and 10-bit serial component SDI signals on input and 10-bit one on output which is totally compliant with CCIR656 and SMPTE259m. During passing a signal through the card all service information is saved and sound packets can be either saved or replaced depending on needs. Input signal is being checked for errors with control sum detection using EDH method. EDH packets on output are always formed all over again in accordance to SMPTE165 recommendation.

All cards work in external synchronization mode by input video signal. If just computer graphics is being outputted than synch signal can be fed either to main input or to separate aux analog input existing on Stream Alpha SDI, Stream Alpha Logo-SDI and Stream Alpha Component cards. If there is no external synchronization a built-n generator is used.

For use of devices being described along with external switcher having DSK (Down Stream Key) there is an output of a key signal (alpha-channel) in analog format, and for Stream Alpha SDI and Stream Logo SDI — in digital format. Card setup utility allows defining both positive and negative key signal delay in wide range of values relatively to graphics outputted.

When the computer’s power is off or bypass mode is on the inputs and outputs of all devices are connected to each other via relay and 75 Ohm load is disconnected. When power is on again and during initialization period no distortions in signal occur.

The new model got a possibility of display in real time on computer monitor either input signal or result of mixing it with computer graphics. The quality of display is so high that there is no need to have special TV monitor.

Buffer for computer graphics

Video card’s memory buffer for computer graphics output has 720×576 points volume for video systems with 50 Hz frame rate and 720×480 points — for 60 Hz frame rate. Each point (pixel) has 32-bit representation with 24 bits used for its color depth (16 millions color grades) and other 8 bits used for definition of one of 256 transparency grade (alpha-channel).

Although chrominance component of a computer graphics pixel has 24-bit representation (8×8×8) for mixing 30-bit representation (10×10×10) is used. I. e. if input signal was 10-bit it will be unchanged after mixing on the output.

Memory used for graphics buffer as well as PCI bus bandwidth of modern computers allow totally real time refreshing buffer’s content with no frame drops and transferring uncompressed video (32 bits per pixel) along with audio. Audio can be embedded to output SDI signal and simultaneously outputted via computer’s audio card. All this allows using a video card for playout not only mute titles and captions but also full-screen animated clips with audio. For this purpose there is no need in separate workstaion with NLE card because whole output is being done via single card and from single computer. It sufficiently simplifies common wiring scheme and lets easy and reliably performing playout automation which is realized in Tele system included into Alpha Pro package.

Rear projection

Another method of mixing proportions detection is rear projection. In this case their own mixing proportion for mixing with computer graphics is defined for particular color groups of input video signal. And if previously 12-bit (4×4×4) color space was mentioned which allowed defining keying areas pretty draft than now due to associated memory use color depth has reached 24 bits (8×8×8) which along with semitransparent mixing provides very good precision of keying on the edge of image and computer graphics avoiding edges “boiling”. If passing through signal is noisy the matte for its lower bits can be used.

Signals format conversion

Stream Alpha SDI video card beside digital serial input has also analog YUV/RGB, S-Video and composite inputs. The card can output YUV/RGB, S-Video and composite signals (previously the card had additional composite output only) in parallel to SDI signal no matter which input used. PAL, SECAM, NTSC standards signals can be fed to input getting PAL and NTSC only on output. Frame rate is not converted, e. g. NTSC can be obtained from NTSC only.

Important feature of input decoder is 9-bit processing and separation of luminance and chrominance in PAL, SECAM or NTSC composite input signal using comb filter (in contrast to previous models with rejection filter). It doesn’t lead to narrowing of chrominance channel bandwidth. 9-bit processing lets saving all 256 chrominance grades during digitization in contrast to 160…170 grades as it occurs in a case of 8-bit processing.

For forming signals of analog outputs 10-bit A-to-D converter with 4-times oversampling s used. It lets do full high frequency noise filtering without narrowing output signals luminance channel bandwidth. If SDI output signal is really 10-bit it is visible also in output analog signal.

Single frames and sequences capture

Stream Alpha SDI can capture an image from any of its input: composite, S-Video, YUV/RGB and SDI. Last one is most important because bit depth for each component is preserved. Video card allows recording video sequences in real time to hard disk or to memory of computer with no compression and frame drops. Such SDI/YUV/RGB capture devices are pretty rare and can be of use in video production: for NLS, slow motion repeats or image libraries. Using such two cards one can create delay line for several seconds or even minutes.

Additional processing of video and open architecture

The card has powerful general purpose Philips Trimedia processor and memory for applications downloaded. It means that downloading new micro program for virtual logical elements functioning into memory it is possible to change no just video card’s logical scheme but also video processing algorithms without any changes in hardware. For example, there are possibilities to:

• Add features for compressed images processing;
• Download program for motion detection in input signal which is really used in surveillance and security systems developed by Stream Labs. Company;
• Track related area in rear projection systems;
• Textures overlay in real time using input image etc.

There are many different tasks and hardware is ready for their realization. It is important that these tasks are performed in parallel and computer’s central processor is not loaded.

Stream Logo SDI

Most close to Stream Alpha SDI in terms of functions is stand-alone Stream Logo SDI logo generator. It just doesn’t have real time input/output of video into computer. Logo generator operates either autonomously or under control by buttons or GPI, or is connected to a network for remote control. In last mode logos, captions and single frame download is performed.

Stream Alpha Component & Stream Alpha Plus

Stream Alpha Component

Stream Alpha Plus

These cards differ from each other (and from Stream Alpha SDI) by inputs and outputs. First one has inputs and outputs for YUV/RGB passing through signal and the second one doesn’t but has YUV/RGB output for computer graphics.

The cards can operate in both analog and digital mixing modes using alpha-channel for it. When mixing of analog signals the output signal is equal to input signal by standard and format. Passing through signal is not decoded and goes through the card with no changes and with preserving its frequency parameters and all service information.

In addition to analog mixing the cards can work in digital mixing mode (digitizing mode). All innovations described above related to signal formats conversion are applicable here that’s why the results of analog and digital mixing are visible alike. A delay of video signal in digitizing mode is about 25 mcs. But this mode allows choosing input format and standard. Thus Stream Alpha Component for example can be used for operations with S-Video and composite signals. Moreover, digital mixing mode allows reducing requirements to input signal quality preserving output signal quality.

The cards have totally digital path for graphics creation and mixing it with passing through video signal (in both modes) which provides better quality of signal being created pplus locking to input signal.

Material provided by Stream Labs. Company