[FFmpeg-devel] [PATCH] avcodec/aaccoder: Limit sf_idx difference for all cases

[Michael Niedermayer]

Fixes: assertion failure
Fixes: 86914558f0a471f038ee1102c02eeb45/signal_sigabrt_7ffff6ae7c37_3051_64ed96a710787ba5d0666746a8562e7d.dee

Found-by: Mateusz "j00ru" Jurczyk and Gynvael Coldwind
Signed-off-by: Michael Niedermayer <michael at niedermayer.cc>
---
 libavcodec/aaccoder.c | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/libavcodec/aaccoder.c b/libavcodec/aaccoder.c
index 284b401..995724b 100644
--- a/libavcodec/aaccoder.c
+++ b/libavcodec/aaccoder.c
@@ -196,7 +196,7 @@ typedef struct TrellisPath {
 static void set_special_band_scalefactors(AACEncContext *s, SingleChannelElement *sce)
 {
     int w, g;
-    int prevscaler_n = -255, prevscaler_i = 0;
+    int prevscaler_n = -255, prevscaler_i = 0, prevscaler_d = -255;
     int bands = 0;
 
     for (w = 0; w < sce->ics.num_windows; w += sce->ics.group_len[w]) {
@@ -211,6 +211,10 @@ static void set_special_band_scalefactors(AACEncContext *s, SingleChannelElement
                 if (prevscaler_n == -255)
                     prevscaler_n = sce->sf_idx[w*16+g];
                 bands++;
+            } else {
+                if (prevscaler_d == -255)
+                    prevscaler_d = sce->sf_idx[w*16+g];
+                bands++;
             }
         }
     }
@@ -227,6 +231,8 @@ static void set_special_band_scalefactors(AACEncContext *s, SingleChannelElement
                 sce->sf_idx[w*16+g] = prevscaler_i = av_clip(sce->sf_idx[w*16+g], prevscaler_i - SCALE_MAX_DIFF, prevscaler_i + SCALE_MAX_DIFF);
             } else if (sce->band_type[w*16+g] == NOISE_BT) {
                 sce->sf_idx[w*16+g] = prevscaler_n = av_clip(sce->sf_idx[w*16+g], prevscaler_n - SCALE_MAX_DIFF, prevscaler_n + SCALE_MAX_DIFF);
+            } else {
+                sce->sf_idx[w*16+g] = prevscaler_d = av_clip(sce->sf_idx[w*16+g], prevscaler_d - SCALE_MAX_DIFF, prevscaler_d + SCALE_MAX_DIFF);
             }
         }
     }
-- 
2.9.3