Optimal transrating via DCT coefficients modification and dropping

Coefficient dropping is a common tool for video transrating in order to adapt it to various network bandwidth constraints. Several recent works propose Lagrangian optimization for finding the optimal retained coefficients for each coded block to achieve the desired bit-rate with minimum distortion. In this paper we extend the Lagrangian optimization procedure by modifying the coefficients prior to dropping them. The purpose of this Lagrangian extension is to provide higher PSNR than other coefficient dropping methods without increasing computational complexity significantly.