AAC encoder: in IS, fix index of sf_idx, band_type

Correct addressing of sf_idx and band_type arrays in I/S code.

Both arrays don't guarantee valid values for subwindows at all
times, depending on which coder is being used, which could result
in reading of garbage values. Instead, only the first subwindow
in the window group has to be used, ie: use w*16+g instead of
(w+w2)*16+g

libavcodec/aacenc_is.c

@@ -53,7 +53,7 @@ struct AACISError ff_aac_is_encoding_err(AACEncContext *s, ChannelElement *cpe,
     for (w2 = 0; w2 < sce0->ics.group_len[w]; w2++) {
         FFPsyBand *band0 = &s->psy.ch[s->cur_channel+0].psy_bands[(w+w2)*16+g];
         FFPsyBand *band1 = &s->psy.ch[s->cur_channel+1].psy_bands[(w+w2)*16+g];
-        int is_band_type, is_sf_idx = FFMAX(1, sce0->sf_idx[(w+w2)*16+g]-4);
+        int is_band_type, is_sf_idx = FFMAX(1, sce0->sf_idx[w*16+g]-4);
         float e01_34 = phase*pow(ener1/ener0, 3.0/4.0);
         float maxval, dist_spec_err = 0.0f;
         float minthr = FFMIN(band0->threshold, band1->threshold);
@@ -66,13 +66,13 @@ struct AACISError ff_aac_is_encoding_err(AACEncContext *s, ChannelElement *cpe,
         is_band_type = find_min_book(maxval, is_sf_idx);
         dist1 += quantize_band_cost(s, &L[start + (w+w2)*128], L34,
                                     sce0->ics.swb_sizes[g],
-                                    sce0->sf_idx[(w+w2)*16+g],
-                                    sce0->band_type[(w+w2)*16+g],
+                                    sce0->sf_idx[w*16+g],
+                                    sce0->band_type[w*16+g],
                                     s->lambda / band0->threshold, INFINITY, NULL, NULL, 0);
         dist1 += quantize_band_cost(s, &R[start + (w+w2)*128], R34,
                                     sce1->ics.swb_sizes[g],
-                                    sce1->sf_idx[(w+w2)*16+g],
-                                    sce1->band_type[(w+w2)*16+g],
+                                    sce1->sf_idx[w*16+g],
+                                    sce1->band_type[w*16+g],
                                     s->lambda / band1->threshold, INFINITY, NULL, NULL, 0);
         dist2 += quantize_band_cost(s, IS, I34, sce0->ics.swb_sizes[g],
                                     is_sf_idx, is_band_type,
@@ -118,11 +118,6 @@ void ff_aac_search_for_is(AACEncContext *s, AVCodecContext *avctx, ChannelElemen
                 ff_sfdelta_can_remove_band(sce1, nextband1, prev_sf1, w*16+g)) {
                 float ener0 = 0.0f, ener1 = 0.0f, ener01 = 0.0f, ener01p = 0.0f;
                 struct AACISError ph_err1, ph_err2, *best;
-                if (sce0->band_type[w*16+g] == NOISE_BT ||
-                    sce1->band_type[w*16+g] == NOISE_BT) {
-                    start += sce0->ics.swb_sizes[g];
-                    continue;
-                }
                 for (w2 = 0; w2 < sce0->ics.group_len[w]; w2++) {
                     for (i = 0; i < sce0->ics.swb_sizes[g]; i++) {
                         float coef0 = fabsf(sce0->coeffs[start+(w+w2)*128+i]);