From b47cef056e51751d5d7b1cb50f91a71110294a9c Mon Sep 17 00:00:00 2001
From: Yaowu Xu <yaowu@google.com>
Date: Thu, 10 Oct 2013 11:00:57 -0700
Subject: [PATCH] change to avoid out-of-range computation
Change-Id: Id5e31833a0ef40de9f64c2f5674af7083233bf14
---
vp9/encoder/vp9_rdopt.c | 13 ++++++++++---
1 file changed, 10 insertions(+), 3 deletions(-)
diff --git a/vp9/encoder/vp9_rdopt.c b/vp9/encoder/vp9_rdopt.c
index 761c5d65e9..e2d24a2dea 100644
--- a/vp9/encoder/vp9_rdopt.c
+++ b/vp9/encoder/vp9_rdopt.c
@@ -3642,10 +3642,17 @@ int64_t vp9_rd_pick_inter_mode_sb(VP9_COMP *cpi, MACROBLOCK *x,
// values, which actually are bigger than this_rd itself. This can
// cause negative best_filter_rd[] values, which is obviously silly.
// Therefore, if filter_cache < ref, we do an adjusted calculation.
- if (cpi->rd_filter_cache[i] >= ref)
+ if (cpi->rd_filter_cache[i] >= ref) {
adj_rd = this_rd + cpi->rd_filter_cache[i] - ref;
- else // FIXME(rbultje) do this for comppred also
- adj_rd = this_rd - (ref - cpi->rd_filter_cache[i]) * this_rd / ref;
+ } else {
+ // FIXME(rbultje) do this for comppsred also
+ //
+ // To prevent out-of-range computation in
+ // adj_rd = cpi->rd_filter_cache[i] * this_rd / ref
+ // cpi->rd_filter_cache[i] / ref is converted to a 256 based ratio.
+ int tmp = cpi->rd_filter_cache[i] * 256 / ref;
+ adj_rd = (this_rd * tmp) >> 8;
+ }
best_filter_rd[i] = MIN(best_filter_rd[i], adj_rd);
}
}
--
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