Scalable HEVC intra frame complexity control subject to quality and bitrate constraints

We introduce an optimal approach for minimizing the computational complexity of HEVC intra encoding subject to constraints in bitrate and reconstruction quality. Our constraint-optimization approach provides an extension to the use of bit constrained rate-distortion optimization so as to minimize encoding time while also delivering sufficient video quality. For our approach, we adaptively control the quantization parameter (QP) and a quad-tree-depth oriented coding tree unit configuration to deliver performance that is optimal in the complexity-rate-quality performance space. Our proposed approach employs a spatially adaptive model that uses neighboring configurations to estimate optimal values for QP and the coding tree unit configuration. We tested our approach using an HEVC standard test video and the ability to dynamically reconfigure between low, medium and high profiles. We found that we can meet the constraints (at 93% (low), 83% (medium) and 93% (high)), while delivering encoding time savings of 13%, 49% and 40% respectively.