LOW-COMPLEXITY TWO-DIMENSIONAL (2D) SEPARABLE TRANSFORM DESIGN WITH TRANSPOSE BUFFER MANAGEMENT

摘要

Methods are provided for reducing the size of a transpose buffer used for computation of a two-dimensional (2D) separable transform. Scaling factors and clip bit widths determined for a particular transpose buffer size and the expected transform sizes are used to reduce the size of the intermediate results of applying the 2D separable transform. The reduced bit widths of the intermediate results may vary across the intermediate results. In some embodiments, the scaling factors and associated clip bit widths may be adapted during encoding.

主权项

1. An apparatus for executing a method for decoding an encoded video bit stream, the method comprising:
entropy decoding a block of transform coefficients from the video bit stream; applying a first one-dimensional (1D) inverse transform of a two-dimensional (2D) separable inverse transform to the block of transform coefficients; reducing a bit width of each intermediate result of applying the first 1D inverse transform, wherein the reduced bit width of a first intermediate result and the reduced bit width of a second intermediate result are different, wherein reducing the bit width comprises scaling the bit width of each intermediate result based on a predetermined shift amount; and clipping the scaled bit width of each intermediate result to a predetermined bit width to attain a final bit width, wherein the final bit width for a first scaled intermediate result is different from the final bit width for a second scaled intermediate result; storing the reduced bit width intermediate results in a transpose buffer; and applying a second 1D inverse transform of the 2D separable inverse transform to the reduced bit width intermediate results to recover a block of residual values.