From: John Stebbins <stebbins@jetheaddev.com>
Date: Wed, 20 Nov 2013 17:26:45 +0000 (-0800)
Subject: ac3dec: make drc_scale exponentially
X-Git-Tag: android-x86-6.0-r1~10^2~2556
X-Git-Url: http://git.osdn.net/view?a=commitdiff_plain;h=c9ca220ef26e36abd22085e6fa156c0dbc43bbf0;p=android-x86%2Fexternal-ffmpeg.git

ac3dec: make drc_scale exponentially

The a52 spec suggests that "partial compression" should scale the
drc value in this manner.

Signed-off-by: Anton Khirnov <anton@khirnov.net>
---

diff --git a/libavcodec/ac3dec.c b/libavcodec/ac3dec.c
index 7172e6378d..e1c696269e 100644
--- a/libavcodec/ac3dec.c
+++ b/libavcodec/ac3dec.c
@@ -756,8 +756,8 @@ static int decode_audio_block(AC3DecodeContext *s, int blk)
     i = !s->channel_mode;
     do {
         if (get_bits1(gbc)) {
-            s->dynamic_range[i] = ((dynamic_range_tab[get_bits(gbc, 8)] - 1.0) *
-                                  s->drc_scale) + 1.0;
+            s->dynamic_range[i] = powf(dynamic_range_tab[get_bits(gbc, 8)],
+                                       s->drc_scale);
         } else if (blk == 0) {
             s->dynamic_range[i] = 1.0f;
         }