Rate-distortion optimised transform competition for intra coding in HEVC

State of the art video coders are based on prediction and transform coding. The transform decorrelates the signal to achieve high compression levels. In this paper we propose improving the performances of the latest video coding standard, HEVC, by adding a set of rate-distortion optimised transforms (RDOTs). The transform design is based upon a cost function that incorporates a bit rate constraint. These new RDOTs compete against classical HEVC transforms in the rate-distortion optimisation (RDO) loop in the same way as prediction modes and block sizes, providing additional coding possibilities. Reductions in BD-rate of around 2% are demonstrated when making these transforms available in HEVC.