[SCM] libav/experimental: fix random dithering of zero-bit mantissas

[siretart at users.alioth.debian.org]

The following commit has been merged in the experimental branch:
commit d5b7144e1ffa9b1a48832ba5995261873cb211d7
Author: Justin Ruggles <justin.ruggles at gmail.com>
Date:   Sat Sep 15 00:43:40 2007 +0000

    fix random dithering of zero-bit mantissas
    
    Originally committed as revision 10495 to svn://svn.ffmpeg.org/ffmpeg/trunk

diff --git a/libavcodec/ac3dec.c b/libavcodec/ac3dec.c
index 66b498b..e59b416 100644
--- a/libavcodec/ac3dec.c
+++ b/libavcodec/ac3dec.c
@@ -518,7 +518,7 @@ static int get_transform_coeffs_ch(AC3DecodeContext *ctx, int ch_index, mant_gro
         tbap = bap[i];
         switch (tbap) {
             case 0:
-                coeffs[i] = ((av_random(&ctx->dith_state) & 0xFFFF) * LEVEL_MINUS_3DB) / 32768.0f;
+                coeffs[i] = ((av_random(&ctx->dith_state) & 0xFFFF) / 65535.0f) - 0.5f;
                 break;
 
             case 1:

-- 
Libav/FFmpeg packaging