An ultra low power adaptive wavelet video encoder with integratedmemory

This paper describes a low-power, single-chip video encoder intended for battery-operated portable applications. Design goals are minimizing system power as well as utilized bandwidth, and maximizing system integration. The encoder achieves competitive compression, with convenient bit rate scalability, using a peak power dissipation of several hundred μW on a video stream of 8-bit gray scale, 30 frame/s, and 128×128 demonstration resolution. Compression is performed using wavelet filtering, zero-trees, and arithmetic coding, all integrated on a single chip (3 million transistors, 1 cm², in 0.6 μm CMOS, operating at 500 kHz), with no external memory or control. Results do not include use of motion compensation, however, hooks are included at algorithmic and architectural levels to add motion compensation at the cost of power dissipation a few times higher, and more internal memory. In the absence of motion compensation, temporal correlation is still utilized through the use of simple frame differencing. The architectural centerpiece is a massively parallel, fine granularity SIMD array of processing elements (PEs). A mapping is made between small image blocks (4×4 pixels on the test chip) and PEs, with each PE containing both memory and logic required for its block. These results are obtained by careful coordination of design in a deep vertical manner, ranging from system, algorithmic, architectural, circuit, and layout, and designing simultaneously for all required algorithmic subcomponents