BlackBerry Limited
Transform coefficient coding for context-adaptive binary entropy coding of video

Abstract:

Methods and devices for encoding and decoding video are described that partition transform blocks into coefficient groups. The coefficients within non-zero coefficients are run-length coded in a reverse scan order within the group. Prior to coefficient coding, data is encoded indicating which coefficient group in group scan order is the last to contain a non-zero coefficient. Then data is encoded indicating the position within that last non-zero coefficient group of the last non-zero coefficient in scan order inside the coefficient group. Thus the decoder is able to decode run-length data knowing the positions of the coefficients and eliminating the need for end-of-block flags.