Method for estimating blockiness in a video frame of transform-based video encoding, the method comprising: - obtaining (S 1) a bitstream of a transform coded video signal, the signal being partitioned into video frames and all operations being performed on a per frame basis, wherein coefficients constituting transforms encoded in the bitstream of the video frames are read, - averaging the coefficients of the transforms encoded in the video bitstream into one averaged transform matrix per transform block size i, - generating or making available one weighting matrix per averaged transform of block size i, comprising weighting factors, - computing intermediate weighted average transform matrices by processing each averaged transform matrix with the corresponding weighting matrix, - processing all members of each weighted and averaged transform matrix into a single value per transform of block size i, to obtain an intermediate signal Bls[i], - computing a single value Bl 0 by weighting the values of the intermediate signal Bls according to an area in the respective video frame and adding up the weighted Bls[i], wherein the area is the area, which the quantity of the transform matrices of block size i cover per video frame, and wherein this area is dependent on the number of transforms of a specific block size i, NTr[i], in the examined frame and the number of pixels each of these transforms covers, using the formula Bl0 = Bls 4 × 4 * NTr 4 × 4 + 4 * Bls 8 × 8 * NTr 8 × 8 + 16 * Bls 16 × 16 * NTr 16 × 16 +... and, wherein blockiness is further estimated as Bl1 using a factor C dependent on a frame averaged quantisation parameter QP and a codec dependent maximum QP, QP_max, were C is defined as C = exp 5 * QP _ max − QP / QP _ max, and wherein Bl 1 = Bl 0 * C QP. - obtaining (S 1) a bitstream of a transform coded video signal, the signal being partitioned into video frames and all operations being performed on a per frame basis, wherein coefficients constituting transforms encoded in the bitstream of the video frames are read, - averaging the coefficients of the transforms encoded in the video bitstream into one averaged transform matrix per transform block size i, - generating or making available one weighting matrix per averaged transform of block size i, comprising weighting factors, - computing intermediate weighted average transform matrices by processing each averaged transform matrix with the corresponding weighting matrix, - processing all members of each weighted and averaged transform matrix into a single value per transform of block size i, to obtain an intermediate signal Bls[i], - computing a single value Bl 0 by weighting the values of the intermediate signal Bls according to an area in the respective video frame and adding up the weighted Bls[i], wherein the area is the area, which the quantity of the transform matrices of block size i cover per video frame, and wherein this area is dependent on the number of transforms of a specific block size i, NTr[i], in the examined frame and the number of pixels each of these transforms covers, using the formula Bl0 = Bls 4 × 4 * NTr 4 × 4 + 4 * Bls 8 × 8 * NTr 8 × 8 + 16 * Bls 16 × 16 * NTr 16 × 16 +... and, wherein blockiness is further estimated as Bl1 using a factor C dependent on a frame averaged quantisation parameter QP and a codec dependent maximum QP, QP_max, were C is defined as C = exp 5 * QP _ max − QP / QP _ max, and wherein Bl 1 = Bl 0 * C QP. wherein the area is the area, which the quantity of the transform matrices of block size i cover per video frame, and wherein this area is dependent on the number of transforms of a specific block size i, NTr[i], in the examined frame and the number of pixels each of these transforms covers, using the formula Bl0 = Bls 4 × 4 * NTr 4 × 4 + 4 * Bls 8 × 8 * NTr 8 × 8 + 16 * Bls 16 × 16 * NTr 16 × 16 +... and, wherein blockiness is further estimated as Bl1 using a factor C dependent on a frame averaged quantisation parameter QP and a codec dependent maximum QP, QP_max, were C is defined as C = exp 5 * QP _ max − QP / QP _ max, and wherein Bl 1 = Bl 0 * C QP.