San Diego, California-based Brooktree Corp has come up with two devices – a single-chip decoder and Video CacheDAC that mixes video and graphics for displaying in a window – to enable manufacturers to develop cheap, high quality desktop video systems. The devices are expected to have an instant appeal to vendors wanting to differentiate their high-end ranges from low-end lines with add in video boards and ‘video ready’ motherboards. The Bt812 is claimed to be the world’s first single chip video decoder and includes Brooktree’s digital Ultralock synchronisation technology that helps stabilise incoming video signals. It has two internal 8-bit flash converters that digitise standard NTSC, PAL or S-Video analogue signals to digital RGB or YCrCb video at pixel rates of between 8MHz to 16.5MHz. It can cope with a range of inputs from sources like VCRs and electronic cameras through Ultralock which provides a stable pixel frequency to which the video can be digitally aligned. This, in turn, enables the Bt812 to be implemented with a known, stable clock. Timing signals are also provided so the video data can be stored directly into a frame buffer or First-In-First-Out. Hue, contrast, saturation and brightness levels can then be adjusted. Brooktree says this method is better than traditional genlocking techniques that adjust the system’s pixel clock frequency to accommodate differing video line lengths – and are often too inflexible to cope with the wide range of video inputs available. The Bt812 is offered as a 160-pin PQFP. It is sampling now with production quantities expected in June, costing UKP50 per 100 up.
Asynchronously load graphics
The similarly-priced Bt885 provides a core of RAMDAC functions and can asynchrously load graphics and video through Brooktree’s VideoCache technology to provide 30 frame-per-second output for 1,280 and 1,024 resolution displays. It also includes a YCrCb-to-RGB colour space converter and horizontal scaler; supports 32-bit graphics and video pixels and is Video RAM and DRAM subsystem-compatible. The device boosts software-generated video performance, making it a low-cost alternative for costly hardware-based decompression systems for general purpose systems – it is not suitable for top quality professional video, Brooktree admits. It can be used to boost unified dual or frame buffer subsystems. But Brooktree says it will be most effective in systems that do not have a separate buffer, and store the smallest CIF or CCRIR video formats in the unused portion of the existing graphics frame buffer, scaled as required. The device has a graphics port with colour look up tables, 15-, 16- and 24-bit RGB support and 8:1 to 1:1 multiplex modes. There is also additional timing support including clock doubling to ease system design and keep costs down. The dedicated video port accepts either 8- or 16-bit data streams and enables on-screen switching. It operates with video decompression and video processor chips using programmable interpolation enabling video to mix with graphics data at the same rate. The Bt885 also comes in a 160-pin PQFP package and is expected to ship in April or May after Brooktree has fine-tuned all the circuitry. It and the Bt812 are available directly from Brooktree or from UK distributor Thame Components Ltd. Brooktree says its new technology will more than half the cost of bringing video to 80486 and Pentium users. This is largely due to VideoCache technology which solves the traditional bandwidth bottleneck caused by video input-output, which has decelerated development; serves to partition graphics and video subsystems; and enables designers to eliminate the duplicate components often found in conventional systems. The company is already working with OEM customers including IBM, Compaq and Dell and says that the first product implementing its technology will be released by an unnamed party by the end of the year. Brooktree’s emerging communications group is also said to be busy. It has just taken over Base2 Systems Inc in Boulder, Colorado and intends to splash out on a few m
ore worthy acquisitions this year, but it’s too early to name names.
