[FFmpeg-cvslog] avcodec/ac3: use M_SQRT1_2, M_SQRT2

[Ganesh Ajjanagadde]

ffmpeg | branch: master | Ganesh Ajjanagadde <gajjanagadde at gmail.com> | Tue Nov 10 22:26:25 2015 -0500| [94565f37919699ff1c6eaf684be85764452c0adc] | committer: Ganesh Ajjanagadde

avcodec/ac3: use M_SQRT1_2, M_SQRT2

This uses M_SQRT1_2, M_SQRT2 instead of the actual literals. This yields
greater precision in some places in avcodec/ac3, while fixed point
values remain unchanged.

Reviewed-by: Clément Bœsch <u at pkh.me>
Signed-off-by: Ganesh Ajjanagadde <gajjanagadde at gmail.com>

> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=94565f37919699ff1c6eaf684be85764452c0adc
---

 libavcodec/ac3.h |    6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/libavcodec/ac3.h b/libavcodec/ac3.h
index ff36249..747f2f5 100644
--- a/libavcodec/ac3.h
+++ b/libavcodec/ac3.h
@@ -97,13 +97,13 @@ typedef float                   SHORTFLOAT;
 
 #endif /* USE_FIXED */
 
-#define AC3_LEVEL(x)            ROUND15((x) * FIXR15(0.7071067811865476))
+#define AC3_LEVEL(x)            ROUND15((x) * FIXR15(M_SQRT1_2))
 
 /* pre-defined gain values */
-#define LEVEL_PLUS_3DB          1.4142135623730950
+#define LEVEL_PLUS_3DB          M_SQRT2
 #define LEVEL_PLUS_1POINT5DB    1.1892071150027209
 #define LEVEL_MINUS_1POINT5DB   0.8408964152537145
-#define LEVEL_MINUS_3DB         0.7071067811865476
+#define LEVEL_MINUS_3DB         M_SQRT1_2
 #define LEVEL_MINUS_4POINT5DB   0.5946035575013605
 #define LEVEL_MINUS_6DB         0.5000000000000000
 #define LEVEL_MINUS_9DB         0.3535533905932738