Fast Quantization Method With Simplified Rate–Distortion Optimized Quantization for an HEVC Encoder

Low Complexity Quantization in High Efficiency Video Coding

“…In [33], the RDOQ bypass scheme is proposed based on the statistics of transform coefficients. In particular, even though RDOQ achieves considerable performance improvements for HEVC, it cannot always bring variations to the quantized level compared to the hard-decision quantization.…”

“…In the literature, various rate and distortion models have been investigated [36][37][38][39], generally with the aim of efficient bit allocation, rate control, and fast RDO decision. However, only a few RD modeling studies targeting on accelerating quantization have been conducted [33,[40][41][42].…”

“…, the RD cost difference with respect to different quantization candidates are derived. In particular, Lee et al [33] formulated a simplified level adjustment method with the ∆J estimation model as follows [33],…”

“…wherein ∆D and ∆R denote the differences of the distortions and rates between l ceil i,j and l f loor i,j for the coefficient at position (i, j). By involving the float expression l f loat i,j of the pre-quantization result, the ∆D is given by [33],…”

“…In this way, the dequantization process can be safely removed. Regarding the rate estimation, a series of syntax elements such as "significant_flag", "greater_than_one", "greater_than_two" and "remaining_level", are involved in the coding of the quantized coefficient, such that the coding bit differences between l ceil i,j and l f loor i,j can be represented as follows [33],…”