Early Multimedia Talent

Performance

ATI introduced the Mach64 in 1994. The chip powered the Graphics Xpression and Graphics Pro Turbo. The first Mach64 had hardware support for YUV to RGB color space conversion. This was a significant milestone in providing MPEG video acceleration on the PC.

Pixels in standard computer graphics are modeled with different intensities of red, green and blue light. Standard video formats store data differently. With a 24-bit color depth, for example, the color white would be represented with maximum values in each of the three RGB color channels.

Most video compression algorithms, including MPEG, store data in a different format. Instead they use YUV. One channel, Y, is used to represent luminosity (similar to brightness) and then remaining U and V channels contain color data. In this format, the color white could be presented with a maximum signal in Y. No data in the other channels would be necessary. This seemingly unusual approach has its roots in the development of our color TV system which is backward compatible with black and white TVs.

Moving the conversion from one pixel format to the other in hardware allowed smooth 30fps software MPEG-1 playback on PCs without the need for expensive ReelMagic decoders.

Quality

The next breakthrough came the following year with the Mach64-VT chipset, found in cards such as the ATI Video Xpression. The original Mach64 allowed videos to be played back at high speed by off-loading the color space conversion from the CPU. The VT edition of the Mach64 added filtering on both the X and Y axes. Now, videos with a source resolution of 320x240 could be scaled to 1024x768 without any blocky pixels.