aac: move sample_fmt selection before decoder configuration.

The decoder configuration initializes the sbr mdct, which needs to know about the sample format to properly take the scale factor into account.
Signed-off-by: NMichael Niedermayer <michaelni@gmx.at>

libavcodec/aacdec.c

@@ -842,6 +842,14 @@ static av_cold int aac_decode_init(AVCodecContext *avctx)
     ac->avctx = avctx;
     ac->oc[1].m4ac.sample_rate = avctx->sample_rate;
 
+    if (avctx->request_sample_fmt == AV_SAMPLE_FMT_FLT) {
+        avctx->sample_fmt = AV_SAMPLE_FMT_FLT;
+        output_scale_factor = 1.0 / 32768.0;
+    } else {
+        avctx->sample_fmt = AV_SAMPLE_FMT_S16;
+        output_scale_factor = 1.0;
+    }
+
     if (avctx->extradata_size > 0) {
         if (decode_audio_specific_config(ac, ac->avctx, &ac->oc[1].m4ac,
                                          avctx->extradata,
@@ -877,14 +885,6 @@ static av_cold int aac_decode_init(AVCodecContext *avctx)
         }
     }
 
-    if (avctx->request_sample_fmt == AV_SAMPLE_FMT_FLT) {
-        avctx->sample_fmt = AV_SAMPLE_FMT_FLT;
-        output_scale_factor = 1.0 / 32768.0;
-    } else {
-        avctx->sample_fmt = AV_SAMPLE_FMT_S16;
-        output_scale_factor = 1.0;
-    }
-
     AAC_INIT_VLC_STATIC( 0, 304);
     AAC_INIT_VLC_STATIC( 1, 270);
     AAC_INIT_VLC_STATIC( 2, 550);