nes loop filtering as optional and recommends a separable two-dimensional For QUANT even spatial filter design which is implemented by cascading REC_LEVEL = QUANT (2xCOEFF_VALUE+1) two identical one dimensional finite impulse response (FIR) filters. The coefficients of the 1D filter are [1, 2, 1] - 1, for COEFF_LEVEL>0, for pixels inside the block, and [0, 1, 0] (no filtering) for REC_LEVEL = QUANT X (2xCOEFF_VALUE-1) pixels on the block boundary. + 1, for COEFF_VALUE< The MQUANT parameter is controlled by the state of the transmission buffer in order to prevent overflow or underflow conditions. The dynamic range of the If COEFF VALUE = 0, then REC LEVEL : 0, DCT macroblock coefficients extends between where REC LEVEL is the reconstruction value, QUANT [-2047, 2047]. They are quantized to the range is 1/2 the macroblock quantization step size ranging from [-127, , 127] using one of the 31 quantizer step sizes 1-31, and COEFF_VALUE is the quantized DCT as determined by the GQUANT parameter. The step coefficient. size is an even integer in the range of [2,..., 62]. To increase the coding efficiency, lossless variable GQUANT can be overridden at the Macroblock layer length coding is applied to the quantized DCT co- by MQUANT to clip or expand the range prescribed efficients. The coefficient matrix is scanned in a zig-zag by GQUANT SO that the transmission buffer is better manner in order to maximize the number of zero co- utilized. The ITU-T RM8 liquid level control model efficient run-lengths. The VLC encodes events defined as specifies the inspection of 64 Kbit transmission buffers the combination of a run-length of zero coefficients after encoding 11 macroblocks. The step size of the preceding a nonzero coefficient, and the value of the quantizer should be increased (decreasing the bitrate) if nonzero coefficient, i.e., EVENT = (RUN, VALUE). The the buffer is full, and vice versa, the step size should be VLC EVENT tables are defined in [4]. decreased (increasing the bitrate) if the buffer is empty. The actual des