From a4d906c13228ac79ed83c4c55b18df4698224db9 Mon Sep 17 00:00:00 2001
From: Deb Mukherjee <debargha@google.com>
Date: Tue, 11 Jun 2013 09:31:33 -0700
Subject: [PATCH] Minor change in forward updates
Removes the case of coding prob = 0 for forward updates, since that
is not an allowed probability to code.
Slightly improves efficiency but may not matter in practice.
Change-Id: I3b4caf82e8f0891992f0706d4089cc5a27568dba
---
vp9/decoder/vp9_decodframe.c | 7 ++++---
vp9/encoder/vp9_bitstream.c | 6 ++++--
2 files changed, 8 insertions(+), 5 deletions(-)
diff --git a/vp9/decoder/vp9_decodframe.c b/vp9/decoder/vp9_decodframe.c
index 43015b987b..fa1f8a46d7 100644
--- a/vp9/decoder/vp9_decodframe.c
+++ b/vp9/decoder/vp9_decodframe.c
@@ -156,13 +156,14 @@ static int merge_index(int v, int n, int modulus) {
}
static int inv_remap_prob(int v, int m) {
- const int n = 256;
+ const int n = 255;
v = merge_index(v, n - 1, MODULUS_PARAM);
+ m--;
if ((m << 1) <= n) {
- return inv_recenter_nonneg(v + 1, m);
+ return 1 + inv_recenter_nonneg(v + 1, m);
} else {
- return n - 1 - inv_recenter_nonneg(v + 1, n - 1 - m);
+ return n - inv_recenter_nonneg(v + 1, n - 1 - m);
}
}
diff --git a/vp9/encoder/vp9_bitstream.c b/vp9/encoder/vp9_bitstream.c
index 2808571e8e..86cd810312 100644
--- a/vp9/encoder/vp9_bitstream.c
+++ b/vp9/encoder/vp9_bitstream.c
@@ -265,7 +265,7 @@ int count_term_subexp(int word, int k, int num_syms) {
static void compute_update_table() {
int i;
- for (i = 0; i < 255; i++)
+ for (i = 0; i < 254; i++)
update_bits[i] = count_term_subexp(i, SUBEXP_PARAM, 255);
}
@@ -277,9 +277,11 @@ static int split_index(int i, int n, int modulus) {
}
static int remap_prob(int v, int m) {
- const int n = 256;
+ const int n = 255;
const int modulus = MODULUS_PARAM;
int i;
+ v--;
+ m--;
if ((m << 1) <= n)
i = recenter_nonneg(v, m) - 1;
else
--
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