Patent ID: 7227901
Filing Date: 2007-06-05
Classification: H04N

Abstract:
1. A method of filtering samples to minimise coding artifacts introduced at a block boundary in a block-based video encoder, the method having the steps of: (a) checking content activity on every line of samples said block boundary; (b) determining whether the filtering process will modify the sample values on the line of samples based on content activity thresholds, said content activity thresholds being dependent on an average quantization parameter and a selected filter offset parameter; (c) determining whether a block on either side of the block boundary was coded using either intra or inter prediction; (d) providing a pair of filter modes, (e) selecting one of the pair of filter modes for filtering the samples, wherein said content-dependent activity checks include a pair of activity threshold values, ALPHA (α) and BETA (β), to determine whether sample values will be modified, and where the values of said activity thresholds are determined based on a pair of indices that are used to access the tables of these parameter values, these indices being calculated using the average quantization parameter, QP