static int dct_quantize_c(MpegEncContext *s, DCTELEM *block, int n, int qscale, int *overflow) { int i, j, level, last_non_zero, q; const int *qmat; int bias; int max=0; unsigned int threshold1, threshold2; av_fdct (block); /* we need this permutation so that we correct the IDCT permutation. will be moved into DCT code */ block_permute(block); if (s->mb_intra) { if (!s->h263_aic) { if (n < 4) q = s->y_dc_scale; else q = s->c_dc_scale; q = q << 3; } else /* For AIC we skip quant/dequant of INTRADC */ q = 1 << 3; /* note: block[0] is assumed to be positive */ block[0] = (block[0] + (q >> 1)) / q; i = 1; last_non_zero = 0; qmat = s->q_intra_matrix[qscale]; bias= s->intra_quant_bias<<(QMAT_SHIFT - 3 - QUANT_BIAS_SHIFT); } else { i = 0; last_non_zero = -1; qmat = s->q_inter_matrix[qscale]; bias= s->inter_quant_bias<<(QMAT_SHIFT - 3 - QUANT_BIAS_SHIFT); } threshold1= (1<<(QMAT_SHIFT - 3)) - bias - 1; threshold2= threshold1<<1; for(;i<64;i++) { j = zigzag_direct[i]; level = block[j]; level = level * qmat[j]; // if( bias+level >= (1<<(QMAT_SHIFT - 3)) // || bias-level >= (1<<(QMAT_SHIFT - 3))){ if(((unsigned)(level+threshold1))>threshold2){ if(level>0){ level= (bias + level)>>(QMAT_SHIFT - 3); block[j]= level; }else{ level= (bias - level)>>(QMAT_SHIFT - 3); block[j]= -level; } max |=level; last_non_zero = i; }else{ block[j]=0; } } *overflow= s->max_qcoeff < max; //overflow might have happend return last_non_zero; }