Serial links in network on chip provide advantages in terms of reduced wiring area, reduced switch complexity and power. However, serial links offer lower bandwidth in comparison to parallel schemes. Poor bandwidth increases the risk of congestion and potential loss of packetised data. This paper proposes a simple yet effective real-time compression technique that reduces the amount of bits sent over serial links. The proposed technique reduces the number of bits and the number of transitions when compared to the original uncompressed data. A case study showing the results of compression on two MPEG1 coded picture data shows average bit reductions of approximately 17% to 47% and average transition reductions of approximately 15% to 24% over a serial link.