aacenc: move the TNS search and filtering before PNS

The original plan was to have TNS use data from the PNS search to better
tune itself to noise but this was never used nor necessary. This should
slightly boost the PNS accuracy if TNS was used.
Signed-off-by: Rostislav Pehlivanov <atomnuker@gmail.com>

libavcodec/aacenc.c

@@ -678,14 +678,14 @@ static int aac_encode_frame(AVCodecContext *avctx, AVPacket *avpkt,
             for (ch = 0; ch < chans; ch++) { /* TNS and PNS */
                 sce = &cpe->ch[ch];
                 s->cur_channel = start_ch + ch;
-                if (s->options.pns && s->coder->search_for_pns)
-                    s->coder->search_for_pns(s, avctx, sce);
                 if (s->options.tns && s->coder->search_for_tns)
                     s->coder->search_for_tns(s, sce);
                 if (s->options.tns && s->coder->apply_tns_filt)
                     s->coder->apply_tns_filt(s, sce);
                 if (sce->tns.present)
                     tns_mode = 1;
+                if (s->options.pns && s->coder->search_for_pns)
+                    s->coder->search_for_pns(s, avctx, sce);
             }
             s->cur_channel = start_ch;
             if (s->options.intensity_stereo) { /* Intensity Stereo */