<title>Very low cost video wavelet codec</title>

Abstract

This paper describes a motion Wavelet transform Zero Tree (WZT) codec which achieves good compression ratios and can be implemented in a single ASIC of modest size (and very low cost). WZT includes a number of trade-offs which reduce the compression rate but which simplify the implementation and reduce the cost. The figure of merit in our codec is ASIC silicon area required, and we are willing to sacrifice some rate/distortion performance with respect to the best available algorithms to that goal.The codec employs a group of pictures (GOP) of two interlaced video frames (i.e., four video fields). Each such field is coded by the well-known transform method, whereby the image is subjected to a 2-D linear transform, the transform values are quantized, and the resulting values coded (e.g., by a zero-tree method). To that goal we are using 3D wavelet transform, dyadic quantization and various entropy codecs. In the temporal direction a temporal transform is used instead of motion estimation.Some of the technical innovations that enable the above features set are:• Edge filters which enable blockwise processing while preserving quadratic continuity across block boundaries, greatly reducing blocking artifacts.• Field image compression which reduces memory requirements for fields within a GOP.