NON-ZERO ROUNDING AND PREDICTION MODE SELECTION TECHNIQUES IN VIDEO ENCODING

摘要

In one aspect of this disclosure, rounding adjustments to bi-directional predictive data may be purposely eliminated to provide predictive data that lacks any rounding bias. In this case, rounded and unrounded predictive data may both be considered in a rate-distortion analysis to identify the best data for prediction of a given video block. In another aspect of this disclosure, techniques are described for selecting among default weighted prediction, implicit weighted prediction, and explicit weighted prediction. In this context, techniques are also described for adding offset to prediction data, e.g., using the format of explicit weighted prediction to allow for offsets to predictive data that is otherwise determined by implicit or default weighted prediction.

主权项

1. A method of encoding video data, the method comprising:
receiving a current video block; determining a first prediction block from a reference frame in a first list; determining a second prediction block from a reference frame in a second list; generating a weighted prediction data that depends on at least the two prediction blocks from the reference frames in the two or more lists of data and includes at least two offsets and a rounding adjustment, wherein generating the weighted prediction data comprises:
left-shifting a sum of the at least two offsets by a rounding adjustment to generate a first intermediate value;summing the product of the first prediction block by a first weighting factor, the product of the second prediction block by a second weighting factor, and two raised to the rounding adjustment to generate a second intermediate; andright-shifting the sum of the first intermediate value and the second intermediate value by the rounding adjustment plus one to generate the weighted prediction data; determining a residual block as a difference between the current video block and the weighted prediction data; transforming the residual block to generate a residual transform coefficient block; quantizing the residual transform coefficient block to generate quantized residual coefficients; and entropy coding the quantized residual coefficients to produce an encoded video bitstream.