aacenc: Use an estimated codebook for the TLS (two loop search).

Originally committed as revision 23134 to svn://svn.ffmpeg.org/ffmpeg/trunk

libavcodec/aaccoder.c

@@ -604,9 +604,26 @@ static void search_for_quantizers_twoloop(AVCodecContext *avctx,
                         continue;
                     }
                     minscaler = FFMIN(minscaler, sce->sf_idx[w*16+g]);
-                    for (cb = 0; cb <= ESC_BT; cb++) {
+                    {
                         float dist = 0.0f;
                         int bb = 0;
+                        float maxval = 0.0f;
+                        float Q = ff_aac_pow2sf_tab[200 - sce->sf_idx[w*16+g] + SCALE_ONE_POS - SCALE_DIV_512];
+                        float Q34 = sqrtf(Q * sqrtf(Q));
+                        int qmaxval;
+                        for (w2 = 0; w2 < sce->ics.group_len[w]; w2++) {
+                            for (i = 0; i < sce->ics.swb_sizes[g]; i++) {
+                                maxval = fmaxf(maxval, scaled[w2*128+i]);
+                            }
+                        }
+                        qmaxval = maxval * Q34 + 0.4054;
+                        if      (qmaxval ==  0) cb = 0;
+                        else if (qmaxval ==  1) cb = 1;
+                        else if (qmaxval ==  2) cb = 3;
+                        else if (qmaxval <=  4) cb = 5;
+                        else if (qmaxval <=  7) cb = 7;
+                        else if (qmaxval <= 12) cb = 9;
+                        else                    cb = 11;
                         for (w2 = 0; w2 < sce->ics.group_len[w]; w2++) {
                             int b;
                             dist += quantize_band_cost(s, coefs + w2*128,
@@ -619,10 +636,8 @@ static void search_for_quantizers_twoloop(AVCodecContext *avctx,
                                                        &b);
                             bb += b;
                         }
-                        if (dist < mindist) {
                             mindist = dist;
                             minbits = bb;
-                        }
                     }
                     dists[w*16+g] = (mindist - minbits) / lambda;
                     bits = minbits;