[FFmpeg-cvslog] aacenc_tns: re-enable coefficient compression

[Rostislav Pehlivanov]

ffmpeg | branch: master | Rostislav Pehlivanov <atomnuker at gmail.com> | Fri Aug 21 21:36:06 2015 +0100| [5df166e4305498d58db0350f78f7fade1ec0c029] | committer: Rostislav Pehlivanov

aacenc_tns: re-enable coefficient compression

This time in a platform/compiler-generic way.

Signed-off-by: Rostislav Pehlivanov <atomnuker at gmail.com>

> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=5df166e4305498d58db0350f78f7fade1ec0c029
---

 libavcodec/aacenc_tns.c |   18 +++++++++++-------
 1 file changed, 11 insertions(+), 7 deletions(-)

diff --git a/libavcodec/aacenc_tns.c b/libavcodec/aacenc_tns.c
index fd20923..3b6e835 100644
--- a/libavcodec/aacenc_tns.c
+++ b/libavcodec/aacenc_tns.c
@@ -49,12 +49,16 @@ static inline void conv_to_float(float *arr, int32_t *cof, int num)
 /* Input: quantized 4 bit coef, output: 1 if first (MSB) 2 bits are the same */
 static inline int coef_test_compression(int coef)
 {
-    int res = 0;
-    /*coef = coef >> 3;
-    res += ffs(coef);
-    coef = coef >> 1;
-    res += ffs(coef);*/
-    return 0;
+    int tmp = coef >> 2;
+    int res = ff_ctz(tmp);
+    if (res > 1)
+        return 1;       /* ...00 ->  compressable    */
+    else if (res == 1)
+        return 0;       /* ...10 ->  uncompressable  */
+    else if (ff_ctz(tmp >> 1) > 0)
+        return 0;       /* ...0 1 -> uncompressable  */
+    else
+        return 1;       /* ...1 1 -> compressable    */
 }
 
 static inline int compress_coef(int *coefs, int num)
@@ -62,7 +66,7 @@ static inline int compress_coef(int *coefs, int num)
     int i, res = 0;
     for (i = 0; i < num; i++)
         res += coef_test_compression(coefs[i]);
-    return 0;
+    return res == num ? 1 : 0;
 }
 
 /**