static void search_for_quantizers_twoloop(AVCodecContext *avctx, AACEncContext *s, SingleChannelElement *sce, const float lambda) { int start = 0, i, w, w2, g; int destbits = avctx->bit_rate * 1024.0 / avctx->sample_rate / avctx->channels; float dists[128], uplims[128]; int fflag, minscaler; int its = 0; int allz = 0; float minthr = INFINITY; //XXX: some heuristic to determine initial quantizers will reduce search time memset(dists, 0, sizeof(dists)); //determine zero bands and upper limits for (w = 0; w < sce->ics.num_windows; w += sce->ics.group_len[w]) { for (g = 0; g < sce->ics.num_swb; g++) { int nz = 0; float uplim = 0.0f; for (w2 = 0; w2 < sce->ics.group_len[w]; w2++) { FFPsyBand *band = &s->psy.psy_bands[s->cur_channel*PSY_MAX_BANDS+(w+w2)*16+g]; uplim += band->threshold; if (band->energy <= band->threshold || band->threshold == 0.0f) { sce->zeroes[(w+w2)*16+g] = 1; continue; } nz = 1; } uplims[w*16+g] = uplim *512; sce->zeroes[w*16+g] = !nz; if (nz) minthr = FFMIN(minthr, uplim); allz = FFMAX(allz, nz); } } for (w = 0; w < sce->ics.num_windows; w += sce->ics.group_len[w]) { for (g = 0; g < sce->ics.num_swb; g++) { if (sce->zeroes[w*16+g]) { sce->sf_idx[w*16+g] = SCALE_ONE_POS; continue; } sce->sf_idx[w*16+g] = SCALE_ONE_POS + FFMIN(log2(uplims[w*16+g]/minthr)*4,59); } } if (!allz) return; abs_pow34_v(s->scoefs, sce->coeffs, 1024); //perform two-loop search //outer loop - improve quality do { int tbits, qstep; minscaler = sce->sf_idx[0]; //inner loop - quantize spectrum to fit into given number of bits qstep = its ? 1 : 32; do { int prev = -1; tbits = 0; fflag = 0; for (w = 0; w < sce->ics.num_windows; w += sce->ics.group_len[w]) { start = w*128; for (g = 0; g < sce->ics.num_swb; g++) { const float *coefs = sce->coeffs + start; const float *scaled = s->scoefs + start; int bits = 0; int cb; float mindist = INFINITY; int minbits = 0; if (sce->zeroes[w*16+g] || sce->sf_idx[w*16+g] >= 218) { start += sce->ics.swb_sizes[g]; continue; } minscaler = FFMIN(minscaler, sce->sf_idx[w*16+g]); for (cb = 0; cb <= ESC_BT; cb++) { float dist = 0.0f; int bb = 0; for (w2 = 0; w2 < sce->ics.group_len[w]; w2++) { int b; dist += quantize_band_cost(s, coefs + w2*128, scaled + w2*128, sce->ics.swb_sizes[g], sce->sf_idx[w*16+g], cb, lambda, INFINITY, &b); bb += b; } if (dist < mindist) { mindist = dist; minbits = bb; } } dists[w*16+g] = (mindist - minbits) / lambda; bits = minbits; if (prev != -1) { bits += ff_aac_scalefactor_bits[sce->sf_idx[w*16+g] - prev + SCALE_DIFF_ZERO]; } tbits += bits; start += sce->ics.swb_sizes[g]; prev = sce->sf_idx[w*16+g]; } } if (tbits > destbits) { for (i = 0; i < 128; i++) if (sce->sf_idx[i] < 218 - qstep) sce->sf_idx[i] += qstep; } else { for (i = 0; i < 128; i++) if (sce->sf_idx[i] > 60 - qstep) sce->sf_idx[i] -= qstep; } qstep >>= 1; if (!qstep && tbits > destbits*1.02) qstep = 1; if (sce->sf_idx[0] >= 217) break; } while (qstep); fflag = 0; minscaler = av_clip(minscaler, 60, 255 - SCALE_MAX_DIFF); for (w = 0; w < sce->ics.num_windows; w += sce->ics.group_len[w]) { start = w*128; for (g = 0; g < sce->ics.num_swb; g++) { int prevsc = sce->sf_idx[w*16+g]; if (dists[w*16+g] > uplims[w*16+g] && sce->sf_idx[w*16+g] > 60) sce->sf_idx[w*16+g]--; sce->sf_idx[w*16+g] = av_clip(sce->sf_idx[w*16+g], minscaler, minscaler + SCALE_MAX_DIFF); sce->sf_idx[w*16+g] = FFMIN(sce->sf_idx[w*16+g], 219); if (sce->sf_idx[w*16+g] != prevsc) fflag = 1; } } its++; } while (fflag && its < 10); }