Efficient context model computation design in transform coefficient coding

Abstract

An encoded bitstream is decodable by a processor configured to execute instructions to store, in a first line buffer, first values of a first scan-order diagonal line scanned immediately before a current scan-order diagonal line of a transform block; and store, in a second line buffer, second values of a second scan-order diagonal line scanned immediately before the first scan-order diagonal line. The first values of the first line buffer and the second values of the second line buffer are interleaved in a destination buffer. Using the destination buffer, a probability distribution is selected for coding a current value of the current scan-order diagonal line. The current value is entropy decoded from the bitstream using the probability distribution. One of the second line buffer or the first line buffer is replaced with current values of the current scan-order diagonal line for coding values of an immediately subsequent scan-order diagonal line.