Real-time video between two PC's over analogue telephone lines

Abstract

The aim of this project was to transmit Real-Time Video between two PC's over an analogue telephone line using modems. The two PC's were equipped with 80386 CPU's and maths co-processors, both running at 33MHz, one serving as a transmitter/coder, the other as a receiver/decoder. The two PC's communicated over the telephone network at 9600 baud, using V32 bis modems. Video sequences were grabbed in real-time using an SVHS video camera connected to a PCVision TM video grabber. These images, were then compressed using Inter-Frame Coding and Intra-Frame Coding techniques employing a Discrete Cosine Transform, and transmitted at a rate of about 2 frames per second. A Fast Discrete Cosine Transform was developed to allow operation in real-time, on a PC without the use of specialized hardware. The algorithm developed was faster than other reported DCT algorithms by a factor of two. This was achieved by trading image quality with speed, by using a truncated Discrete Cosine Transform computation.