Change k limiting code, i think the code was buggy.

If you have ALAC files TEST them! Mine produce the same md5 but the new
code is not identical if limiting does happen.

Originally committed as revision 12872 to svn://svn.ffmpeg.org/ffmpeg/trunk

libavcodec/alac.c

@@ -226,18 +226,20 @@ static void bastardized_rice_decompress(ALACContext *alac,
 
                 k = count_leading_zeros(history) + ((history + 16) >> 6 /* / 64 */) - 24;
 
-                extrabits = show_bits(&alac->gb, k);
+                if (k >= rice_kmodifier)
+                    k = rice_kmodifier;
 
-                block_size = (((1 << k) - 1) & rice_kmodifier_mask) * x
-                           + extrabits - 1;
+                x = (x << k) - x;
+
+                extrabits = show_bits(&alac->gb, k);
 
                 if (extrabits < 2) {
-                    x = 1 - extrabits;
-                    block_size += x;
                     skip_bits(&alac->gb, k - 1);
                 } else {
+                    x += extrabits - 1;
                     skip_bits(&alac->gb, k);
                 }
+                block_size = x;
             }
 
             if (block_size > 0) {