Patch attached.
- Andreas
From 4e50b2adb6de16754b629eaf18fc92d67ecdf1ca Mon Sep 17 00:00:00 2001
From: Andreas Rheinhardt <andreas.rheinha...@outlook.com>
Date: Sat, 8 Mar 2025 15:45:24 +0100
Subject: [PATCH] avcodec/vc2enc: Simplify writing dirac golomb codes
The earlier code used a loop to determine the number of bits used
and called ff_log2() on a power of two (and it would be easy to
keep track of the exponent of said power-of-two); neither GCC nor
Clang optimized the loop away or avoided the ff_log2().
This patch replaces the loop and the log2 with a single av_log2().
Signed-off-by: Andreas Rheinhardt <andreas.rheinha...@outlook.com>
---
libavcodec/vc2enc.c | 30 +++---------------------------
1 file changed, 3 insertions(+), 27 deletions(-)
diff --git a/libavcodec/vc2enc.c b/libavcodec/vc2enc.c
index b82370a753..8e68d7a89d 100644
--- a/libavcodec/vc2enc.c
+++ b/libavcodec/vc2enc.c
@@ -189,23 +189,10 @@ typedef struct VC2EncContext {
static av_always_inline void put_vc2_ue_uint(PutBitContext *pb, uint32_t val)
{
int i;
- int bits = 0;
- unsigned topbit = 1, maxval = 1;
+ int bits = av_log2(++val);
+ unsigned topbit = 1 << bits;
uint64_t pbits = 0;
- if (!val++) {
- put_bits(pb, 1, 1);
- return;
- }
-
- while (val > maxval) {
- topbit <<= 1;
- maxval <<= 1;
- maxval |= 1;
- }
-
- bits = ff_log2(topbit);
-
for (i = 0; i < bits; i++) {
topbit >>= 1;
av_assert2(pbits <= UINT64_MAX>>3);
@@ -219,18 +206,7 @@ static av_always_inline void put_vc2_ue_uint(PutBitContext *pb, uint32_t val)
static av_always_inline int count_vc2_ue_uint(uint32_t val)
{
- int topbit = 1, maxval = 1;
-
- if (!val++)
- return 1;
-
- while (val > maxval) {
- topbit <<= 1;
- maxval <<= 1;
- maxval |= 1;
- }
-
- return ff_log2(topbit)*2 + 1;
+ return 2 * av_log2(val + 1) + 1;
}
/* VC-2 10.4 - parse_info() */
--
2.45.2
_______________________________________________
ffmpeg-devel mailing list
ffmpeg-devel@ffmpeg.org
https://ffmpeg.org/mailman/listinfo/ffmpeg-devel
To unsubscribe, visit link above, or email
ffmpeg-devel-requ...@ffmpeg.org with subject "unsubscribe".
