dct

问题 Is there a way to easily extract the DCT coefficients (and quantization parameters) from encoded images and video? Any decoder software must be using them to decode block-DCT encoded images and video. So I\'m pretty sure the decoder knows what they are. Is there a way to expose them to whomever is using the decoder? I\'m implementing some video quality assessment algorithms that work directly in the DCT domain. Currently, the majority of my code uses OpenCV, so it would be great if anyone

问题 I am looking for a simple algorithm to perform fast DCT (type 2) of a matrix of any size [NxM], and also an algorithm for the inverse transformation IDCT (also called DCT type 3). I need a DCT-2D algorithm, but even a DCT-1D algorithm is good enough because I can use DCT-1D to implement DCT-2D (and IDCT-1D to implement IDCT-2D ). PHP code is preferable, but any algorithm that is clear enough will do. My current PHP script for implementing DCT/IDCT is very slow whenever matrix size is more