virtualenv/FFmpeg
1
0
Fork 0
mirror of https://github.com/FFmpeg/FFmpeg.git synced 2025-08-04 22:03:09 +02:00
Code Issues Releases Activity

avcodec/vp6: Don't reload unnecessarily often in get_vlc2()

Browse Source 
The VLC trees used here have very few different codes
and are therefore guaranteed to not be very deep: The AC/DC
VLCs have 12 elements and therefore a depth <= 11 whereas
the run VLCs have only nine elements and therefore a depth <= 8.
This allows to reduce the worst-case number of reloads for
reading a VLC code.

Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@outlook.com>
This commit is contained in:
Andreas Rheinhardt
2025-04-17 19:48:05 +02:00
parent 57b7783c22
commit e946ba64bf
1 changed files with 3 additions and 3 deletions
Download Patch File Download Diff File Expand all files Collapse all files

6
libavcodec/vp6.c
View File

@ -415,7 +415,7 @@ static int vp6_parse_coeff_huffman(VP56Context *s)
VP56Model *model = s->modelp; VP56Model *model = s->modelp;
uint8_t *permute = s->idct_scantable; uint8_t *permute = s->idct_scantable;
VLC *vlc_coeff; VLC *vlc_coeff;
int coeff, sign, coeff_idx; int sign, coeff_idx;
int b, cg, idx; int b, cg, idx;
int pt = 0; /* plane type (0 for Y, 1 for U or V) */ int pt = 0; /* plane type (0 for Y, 1 for U or V) */
@ -433,11 +433,11 @@ static int vp6_parse_coeff_huffman(VP56Context *s)
} else { } else {
if (get_bits_left(&s->gb) <= 0) if (get_bits_left(&s->gb) <= 0)
return AVERROR_INVALIDDATA; return AVERROR_INVALIDDATA;
coeff = get_vlc2(&s->gb, vlc_coeff->table, FF_HUFFMAN_BITS, 3); int coeff = get_vlc2(&s->gb, vlc_coeff->table, FF_HUFFMAN_BITS, 2);
if (coeff == 0) { if (coeff == 0) {
if (coeff_idx) { if (coeff_idx) {
int pt = (coeff_idx >= 6); int pt = (coeff_idx >= 6);
run += get_vlc2(&s->gb, s->runv_vlc[pt].table, FF_HUFFMAN_BITS, 3); run += get_vlc2(&s->gb, s->runv_vlc[pt].table, FF_HUFFMAN_BITS, 1);
if (run >= 9) if (run >= 9)
run += get_bits(&s->gb, 6); run += get_bits(&s->gb, 6);
} else } else