[FFmpeg-cvslog] aaccoder: prevent crash of anmr coder

[Andreas Cadhalpun]

ffmpeg | branch: release/2.8 | Andreas Cadhalpun <Andreas.Cadhalpun at googlemail.com> | Fri Dec  4 18:13:07 2015 +0100| [507e0314c0d9107f6e17753950f9aceb6ed3b8d5] | committer: Andreas Cadhalpun

aaccoder: prevent crash of anmr coder

If minq is negative, the range of sf_idx can be larger than
SCALE_MAX_DIFF allows, causing assertion failures later in
encode_scale_factors.

Reviewed-by: Claudio Freire <klaussfreire at gmail.com>
Signed-off-by: Andreas Cadhalpun <Andreas.Cadhalpun at googlemail.com>
(cherry picked from commit 7a4652dd5da0502ff21c183b5ca7d76b1cfd6c51)
Signed-off-by: Andreas Cadhalpun <Andreas.Cadhalpun at googlemail.com>

> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=507e0314c0d9107f6e17753950f9aceb6ed3b8d5
---

 libavcodec/aaccoder.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/libavcodec/aaccoder.c b/libavcodec/aaccoder.c
index 86d598f..e6b57aa 100644
--- a/libavcodec/aaccoder.c
+++ b/libavcodec/aaccoder.c
@@ -499,7 +499,7 @@ static void search_for_quantizers_anmr(AVCodecContext *avctx, AACEncContext *s,
     }
     while (idx) {
         sce->sf_idx[bandaddr[idx]] = minq + q0;
-        minq = paths[idx][minq].prev;
+        minq = FFMAX(paths[idx][minq].prev, 0);
         idx--;
     }
     //set the same quantizers inside window groups