lindsay@gandalf.cs.cmu.edu (Donald Lindsay) (01/06/91)
In article <37606@cup.portal.com> ts@cup.portal.com (Tim W Smith) writes: >>As far a DVI goes (which I know a bit about,too and I didn't get it >>all from books) a CD-ROM can hold up to 70 min. of full-screen, >>full-motion video with good quality stereo audio. >How does this work? Assume 700 meg of data (for easy computing) and >we get 10 meg for each minute of video, or 170 KBytes per second, >or (assuming 30 frames per second) about 6 KBytes/frame. >So how do they get good video from this? Compress the heck out of it? Yes, they compress. Your calculations are fairly close. The compression ratio was not chosen arbitrarily: it makes the data rate come out to the data rate that CD-ROM drives provide. The DVI chip set is two chips: Intel offers them on a single AT- compatible board, with some VRAM, and a DSP for audio. Compression/decompression chip sets seem to be busting out all over. DVI is Intel turf, so the competitors have differentiated themselves - into HDTV, JPEG, low-cost NTSC/VGA merging, and so on. There should be quite a lot of sorting-out in the next two or three years. -- Don D.C.Lindsay .. temporarily at Carnegie Mellon Robotics