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From: Michael Niedermayer <michael@niedermayer.cc>
To: FFmpeg development discussions and patches <ffmpeg-devel@ffmpeg.org>
Subject: [FFmpeg-devel] [PATCH 2/4] avcodec/get_bits: Avoid 2nd bitstream read in GET_VLC() if bits are known at build and small
Date: Tue, 24 Oct 2023 17:04:41 +0200
Message-ID: <20231024150443.7438-2-michael@niedermayer.cc> (raw)
In-Reply-To: <20231024150443.7438-1-michael@niedermayer.cc>

Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
---
 libavcodec/get_bits.h | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/libavcodec/get_bits.h b/libavcodec/get_bits.h
index cfcf97c021c..86cea00494a 100644
--- a/libavcodec/get_bits.h
+++ b/libavcodec/get_bits.h
@@ -581,8 +581,12 @@ static inline const uint8_t *align_get_bits(GetBitContext *s)
         n     = table[index].len;                               \
                                                                 \
         if (max_depth > 1 && n < 0) {                           \
-            LAST_SKIP_BITS(name, gb, bits);                     \
-            UPDATE_CACHE(name, gb);                             \
+            if (av_builtin_constant_p(bits <= MIN_CACHE_BITS/2) && bits <= MIN_CACHE_BITS/2) { \
+                SKIP_BITS(name, gb, bits);                      \
+            } else {                                            \
+                LAST_SKIP_BITS(name, gb, bits);                 \
+                UPDATE_CACHE(name, gb);                         \
+            }                                                   \
                                                                 \
             nb_bits = -n;                                       \
                                                                 \
-- 
2.17.1

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  reply	other threads:[~2023-10-24 15:05 UTC|newest]

Thread overview: 9+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-10-24 15:04 [FFmpeg-devel] [PATCH 1/4] avcodec/magicyuv: Use a compile time constant for vlc_bits Michael Niedermayer
2023-10-24 15:04 ` Michael Niedermayer [this message]
2023-10-27  3:10   ` [FFmpeg-devel] [PATCH 2/4] avcodec/get_bits: Avoid 2nd bitstream read in GET_VLC() if bits are known at build and small Andreas Rheinhardt
2023-10-27 18:38     ` Michael Niedermayer
2023-10-30 20:49       ` Andreas Rheinhardt
2023-10-31  0:25         ` Michael Niedermayer
2023-10-24 15:04 ` [FFmpeg-devel] [PATCH 3/4] avcodec/get_bits: Implement get_vlc_multi() Michael Niedermayer
2023-10-24 15:04 ` [FFmpeg-devel] [PATCH 4/4] avcodec/magicyuv: Set UNCHECKED_BITSTREAM_READER Michael Niedermayer
2023-10-26 21:37 ` [FFmpeg-devel] [PATCH 1/4] avcodec/magicyuv: Use a compile time constant for vlc_bits Andreas Rheinhardt

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