[FFmpeg-devel] [PATCH] avcodec/dcaenc: avoid wasteful cos calls

[Ganesh Ajjanagadde]

cos is an even function; use this.

Signed-off-by: Ganesh Ajjanagadde <gajjanagadde at gmail.com>
---
 libavcodec/dcaenc.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/libavcodec/dcaenc.c b/libavcodec/dcaenc.c
index 5a6bdac..b12d27b 100644
--- a/libavcodec/dcaenc.c
+++ b/libavcodec/dcaenc.c
@@ -169,8 +169,12 @@ static int encode_init(AVCodecContext *avctx)
     if (!cos_table[0]) {
         int j, k;
 
-        for (i = 0; i < 2048; i++) {
+        cos_table[0] = 0x7fffffff;
+        for (i = 1; i < 1025; i++) {
             cos_table[i]   = (int32_t)(0x7fffffff * cos(M_PI * i / 1024));
+            cos_table[2048-i] = cos_table[i];
+        }
+        for (i = 0; i < 2048; i++) {
             cb_to_level[i] = (int32_t)(0x7fffffff * pow(10, -0.005 * i));
         }
 
-- 
2.6.3