[FFmpeg-cvslog] wmavoice: protect against zero-energy in adaptive gain control.

[Ronald S. Bultje]

ffmpeg | branch: master | Ronald S. Bultje <rsbultje at gmail.com> | Tue Dec 20 18:01:05 2016 -0500| [33d7f822f8ed2d1870babc1d04d4d48cf8b6f240] | committer: Ronald S. Bultje

wmavoice: protect against zero-energy in adaptive gain control.

Otherwise the scale factor becomes NaN, resulting in corrupt output.
Fixes #5426.

> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=33d7f822f8ed2d1870babc1d04d4d48cf8b6f240
---

 libavcodec/wmavoice.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/libavcodec/wmavoice.c b/libavcodec/wmavoice.c
index 90dfe20..cd5958c 100644
--- a/libavcodec/wmavoice.c
+++ b/libavcodec/wmavoice.c
@@ -512,7 +512,8 @@ static void adaptive_gain_control(float *out, const float *in,
         speech_energy     += fabsf(speech_synth[i]);
         postfilter_energy += fabsf(in[i]);
     }
-    gain_scale_factor = (1.0 - alpha) * speech_energy / postfilter_energy;
+    gain_scale_factor = postfilter_energy == 0.0 ? 0.0 :
+                        (1.0 - alpha) * speech_energy / postfilter_energy;
 
     for (i = 0; i < size; i++) {
         mem = alpha * mem + gain_scale_factor;