Data processing systems for encoding video data

An apparatus for selecting sample adaptive offset options to use when encoding an array of data elements of a stream of arrays of data elements, the apparatus comprising:

• distortion value determining circuitry, operable to determine a distortion value for a particular set of sample adaptive offset options by:
• generating one or more filtered reconstructed source blocks by applying a sample adaptive offset filter in accordance with the particular set of sample adaptive offset options to one or more reconstructed source blocks corresponding to a source block of the array of data elements being encoded;
• generating a set of error values by comparing the one or more filtered reconstructed source blocks with the source block;
• and
• determining a distortion value for the particular set of sample adaptive offset options using the set of error values;
• and
• sample adaptive offset option selection circuitry operable to select a set of sample adaptive offset options to be used when encoding the source block based on the distortion value;
• wherein the distortion value determining circuitry is operable, for the particular set of sample adaptive offset options comprising an edge offset, to determine the distortion value using a set of error values comprising fewer data values than the source block of data elements;
• wherein the set of error values that is used to determine the distortion value comprises an array of error values;
• wherein for the particular set of sample adaptive offset options comprising an edge offset, the array of error values corresponds to an inner sub-region of a reconstructed source block and the array of error values corresponds to all of the inner data elements of a reconstructed source block.

A non-transitory computer readable storage medium storing computer software code which when executing on a processor performs a method of selecting sample adaptive offset options to use when encoding an array of data elements of a stream of arrays of data elements, the method comprising:

• determining a distortion value for a particular set of sample adaptive offset options by:
• generating one or more filtered reconstructed source blocks by applying a sample adaptive offset filter in accordance with the particular set of sample adaptive offset options to one or more reconstructed source blocks corresponding to a source block of the array of data elements being encoded;
• generating a set of error values by comparing the one or more filtered reconstructed source blocks with the source block;
• and
• determining a distortion value for the particular set of sample adaptive offset options using the set of error values;
• the method further comprising:
• selecting, based on the distortion value, whether to encode the source block using the particular set of sample adaptive offset options;
• wherein for the particular set of sample adaptive offset options comprising an edge offset, the determining of the distortion value comprises using a set of error values comprising fewer data values than the source block of data elements;
• wherein the set of error values that is used to determine the distortion value comprises an array of error values;
• wherein for the particular set of sample adaptive offset options comprising an edge offset, the array of error values corresponds to an inner sub-region of a reconstructed source block and the array of error values corresponds to all of the inner data elements of a reconstructed source block.