Abstract — We consider the problem of lossy source coding under a peak distortion measure in which source symbols are revealed to the encoder in real time and need to be reconstructed by the decoder within a fixed end-to-end delay. Following the lossless case in [3], we investigate the tradeoff between end-to-end delay and the probability of distortion violation. As in the lossless case, the delay-constrained error (distortion-violation) exponent is generally much higher than the fixed-block coding case. I