commit 8570a2ce71d09c85390f06db0ed86bf327944cfb
author Hui Su <huisu@google.com> Tue Oct 01 10:18:47 2019 -0700
committer Hui Su <huisu@google.com> Wed Oct 02 17:11:41 2019 +0000
tree 4fd4aafa007a9a1a1547ba66b5743f9e9c6f4e87
parent 6092a6cd8661aa1b0fbe2258f5bb8a56c13a26fd

Change COEFF_CONTEXT_BITS from 6 to 3

3 bits are enough for the transform coefficient entropy contexts because
they are saturated above 4. Reducing the number of bits help improve
encoding speed. Tests show about 1% instruction counts reduction.

Change-Id: Idcc0b6858dc83409f8da688704802b7b1a832d2e

av1/common/entropy.h

diff --git a/av1/common/entropy.h b/av1/common/entropy.h
index 41218d3..ee78f56 100644
--- a/av1/common/entropy.h
+++ b/av1/common/entropy.h
@@ -48,7 +48,7 @@
 #define BR_CDF_SIZE (4)
 #define COEFF_BASE_RANGE (4 * (BR_CDF_SIZE - 1))
 
-#define COEFF_CONTEXT_BITS 6
+#define COEFF_CONTEXT_BITS 3
 #define COEFF_CONTEXT_MASK ((1 << COEFF_CONTEXT_BITS) - 1)
 #define MAX_BASE_BR_RANGE (COEFF_BASE_RANGE + NUM_BASE_LEVELS + 1)