The transmitter of a video codec system is designed and realized in ECL hardware. This video codec system is capable of carrying one commercial NTSC color television channel with a program audio channel at a rate of 42.9 Mb/s. The transmitter interfaces with a DPCM processor. The transmitter removes the horizontal blanking interval from the composite television signal, converts the quantized difference signal from the DPCM processor into 4/8-bit dual length code and buffers the codes for constant rate transmission. A line synchronization code is multiplexed with audio and video codes to form a serial data link at 42.9 Mb/s. This can be transmitted on a T3 (44.7 Mb/s) digital carrier. The transmitter is composed of four functional units: controller, coder, buffer and multiplexer. This paper describes the design, layout, testing and evaluation of the high speed digital system that results in 2 to 1 data compression of the digital video.