Alternating coding for universal variable length code

Variable length code (VLC) is used in a large variety of lossless compression applications. A specially designed VLC, called "universal variable length code" (UVLC), is utilized in the latest video coding standard H.26L under development. In this work we propose a new coding method under the name "alternating coding" (ALT coding) and apply it to the UVLC. The ALT coded UVLC yields the same high coding efficiency as the original UVLC, but ALT coding also enables immediate decoding, immediate error detection and location in a UVLC packet. It improves the error resiliency and error robustness of the UVLC packet by applying an "error speculation". Results show that the ALT coded UVLC packet always outperforms the original UVLC packet in terms of error resiliency and robustness. Moreover, the simple pattern of ALT coded UVLC can greatly simplify the UVLC decoder architecture and therefore enables small, fast, and low-power decoder design.