[FFmpeg-cvslog] avcodec/sheervideo: Improve creating VLC tables
Andreas Rheinhardt
git at videolan.org
Sat Oct 10 17:02:05 EEST 2020
ffmpeg | branch: master | Andreas Rheinhardt <andreas.rheinhardt at gmail.com> | Sat Oct 10 06:13:21 2020 +0200| [1bff2f3d929b7e1229b9a125e3cf938ece1665cc] | committer: Andreas Rheinhardt
avcodec/sheervideo: Improve creating VLC tables
Don't needlessly copy an array around; don't create a table with
default symbols; and use smaller types to save stack space: The longest
code here is 16 bits, so one can store the codes in this type.
Reviewed-by: Paul B Mahol <onemda at gmail.com>
Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt at gmail.com>
> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=1bff2f3d929b7e1229b9a125e3cf938ece1665cc
---
libavcodec/sheervideo.c | 19 +++++++------------
1 file changed, 7 insertions(+), 12 deletions(-)
diff --git a/libavcodec/sheervideo.c b/libavcodec/sheervideo.c
index ba9aecbb11..3f9b299a1e 100644
--- a/libavcodec/sheervideo.c
+++ b/libavcodec/sheervideo.c
@@ -1782,25 +1782,20 @@ static void decode_rgb(AVCodecContext *avctx, AVFrame *p, GetBitContext *gb)
static int build_vlc(VLC *vlc, const uint8_t *len, int count)
{
- uint32_t codes[1024];
- uint8_t bits[1024];
- uint16_t syms[1024];
- uint64_t index;
+ uint16_t codes[1024];
+ unsigned index;
int i;
index = 0;
for (i = 0; i < count; i++) {
- codes[i] = index >> (32 - len[i]);
- bits[i] = len[i];
- syms[i] = i;
- index += 1ULL << (32 - len[i]);
+ codes[i] = index >> (32 - len[i]);
+ index += 1U << (32 - len[i]);
}
ff_free_vlc(vlc);
- return ff_init_vlc_sparse(vlc, 12, count,
- bits, sizeof(*bits), sizeof(*bits),
- codes, sizeof(*codes), sizeof(*codes),
- syms, sizeof(*syms), sizeof(*syms), 0);
+ return init_vlc(vlc, 12, count,
+ len, sizeof(*len), sizeof(*len),
+ codes, sizeof(*codes), sizeof(*codes), 0);
}
static int decode_frame(AVCodecContext *avctx,
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