diff --git a/libavcodec/aac.h b/libavcodec/aac.h
index b25b40c9c6..2701386376 100644
--- a/libavcodec/aac.h
+++ b/libavcodec/aac.h
@@ -141,6 +141,9 @@ typedef struct PredictorState {
 #define SCALE_MAX_DIFF   60    ///< maximum scalefactor difference allowed by standard
 #define SCALE_DIFF_ZERO  60    ///< codebook index corresponding to zero scalefactor indices difference
 
+#define NOISE_PRE       256    ///< preamble for NOISE_BT, put in bitstream with the first noise band
+#define NOISE_PRE_BITS    9    ///< length of preamble
+
 /**
  * Long Term Prediction
  */
diff --git a/libavcodec/aacenc.c b/libavcodec/aacenc.c
index 7015a2789c..5288afb4a2 100644
--- a/libavcodec/aacenc.c
+++ b/libavcodec/aacenc.c
@@ -388,15 +388,26 @@ static void encode_band_info(AACEncContext *s, SingleChannelElement *sce)
 static void encode_scale_factors(AVCodecContext *avctx, AACEncContext *s,
                                  SingleChannelElement *sce)
 {
-    int off = sce->sf_idx[0], diff;
+    int diff, off_sf = sce->sf_idx[0], off_pns = sce->sf_idx[0];
+    int noise_flag = 1;
     int i, w;
 
     for (w = 0; w < sce->ics.num_windows; w += sce->ics.group_len[w]) {
         for (i = 0; i < sce->ics.max_sfb; i++) {
             if (!sce->zeroes[w*16 + i]) {
-                diff = sce->sf_idx[w*16 + i] - off + SCALE_DIFF_ZERO;
+                if (sce->band_type[w*16 + i] == NOISE_BT) {
+                    diff = sce->sf_idx[w*16 + i] - off_pns;
+                    off_pns = sce->sf_idx[w*16 + i];
+                    if (noise_flag-- > 0) {
+                        put_bits(&s->pb, NOISE_PRE_BITS, diff + NOISE_PRE);
+                        continue;
+                    }
+                } else {
+                    diff = sce->sf_idx[w*16 + i] - off_sf;
+                    off_sf = sce->sf_idx[w*16 + i];
+                }
+                diff += SCALE_DIFF_ZERO;
                 av_assert0(diff >= 0 && diff <= 120);
-                off = sce->sf_idx[w*16 + i];
                 put_bits(&s->pb, ff_aac_scalefactor_bits[diff], ff_aac_scalefactor_code[diff]);
             }
         }