Video compression systems for low-latency applications

Abstract

This dissertation presents an in-depth analysis of latency sources in real-time video compression systems and describes strategies to minimize the system delay. Initially, the latencies of intra-frame and predictive coding in standard-mode video compression systems are examined. A theoretical analysis identifies the bitstream buffers - which are a pre-requisite of constant transmission bit-rate - as major sources of latency. In a second step, the results of experiments conducted using the "leaky-bucket" model on ten video sequences with sub-frame-level resolution are discussed. Based on these observations, the intra refresh coding method is identified as a key technique for low latency in predictive video compression systems. Finally, a novel approach for intra refresh coding is presented, which simultaneously satisfies the traditionally contradictory goals of high coding efficiency and low system latency.