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huffyuvdec: implement trick

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When the joint table does not contain a valid entry, the decoding restarts
from scratch. By implementing the trick of jumping to the 2nd level of the
individual table (and inlining the whole), a speed improvement of 5-10%
is possible.

On a 1000-frames YUV4:2:0 video, before:
362851 decicycles in 422, 262094 runs, 50 skips
182488 decicycles in gray, 262087 runs, 57 skips
Object size: 23584
Overall time: 8.377

After:
346800 decicycles in 422, 262079 runs, 65 skips
168197 decicycles in gray, 262077 runs, 67 skips
Object size: 23188
Overall time: 7.878

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
pull/76/merge
Christophe Gisquet 11 years ago committed by Michael Niedermayer
parent c7e54628e3
commit 11b4703813
1 changed files with 57 additions and 14 deletions
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  1. 71
      libavcodec/huffyuvdec.c

71
libavcodec/huffyuvdec.c
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@ -559,23 +559,62 @@ static av_cold int decode_init_thread_copy(AVCodecContext *avctx)
return 0;
}
/* TODO instead of restarting the read when the code isn't in the first level
* of the joint table, jump into the 2nd level of the individual table. */
#define READ_2PIX(dst0, dst1, plane1){\
uint16_t code = get_vlc2(&s->gb, s->vlc[4+plane1].table, VLC_BITS, 1);\
if(code != 0xffff){\
dst0 = code>>8;\
dst1 = code;\
}else{\
dst0 = get_vlc2(&s->gb, s->vlc[0].table, VLC_BITS, 3);\
dst1 = get_vlc2(&s->gb, s->vlc[plane1].table, VLC_BITS, 3);\
}\
}
#define DUAL_INTERN(dst, table, gb, name, bits, max_depth) \
code = table[index][0]; \
n = table[index][1]; \
if (max_depth > 1 && n < 0) { \
LAST_SKIP_BITS(name, gb, bits); \
UPDATE_CACHE(name, gb); \
\
nb_bits = -n; \
index = SHOW_UBITS(name, gb, nb_bits) + code; \
code = table[index][0]; \
n = table[index][1]; \
if (max_depth > 2 && n < 0) { \
LAST_SKIP_BITS(name, gb, nb_bits); \
UPDATE_CACHE(name, gb); \
\
nb_bits = -n; \
index = SHOW_UBITS(name, gb, nb_bits) + code; \
code = table[index][0]; \
n = table[index][1]; \
} \
} \
dst = code; \
LAST_SKIP_BITS(name, gb, n)
#define GET_VLC_DUAL(dst0, dst1, name, gb, dtable, table1, table2, \
bits, max_depth, rsvd ) \
do { \
unsigned int index = SHOW_UBITS(name, gb, bits); \
int code = dtable[index][0]; \
int n = dtable[index][1]; \
\
if (code != rsvd && n>0) { \
dst0 = code>>8; \
dst1 = code; \
LAST_SKIP_BITS(name, gb, n); \
} else { \
int nb_bits; \
DUAL_INTERN(dst0, table1, gb, name, bits, max_depth); \
\
UPDATE_CACHE(re, gb); \
index = SHOW_UBITS(name, gb, bits); \
DUAL_INTERN(dst1, table2, gb, name, bits, max_depth); \
} \
} while (0)
#define READ_2PIX(dst0, dst1, plane1)\
UPDATE_CACHE(re, &s->gb); \
GET_VLC_DUAL(dst0, dst1, re, &s->gb, s->vlc[4+plane1].table, \
s->vlc[0].table, s->vlc[plane1].table, \
VLC_BITS, 3, 0xffff)
static void decode_422_bitstream(HYuvContext *s, int count)
{
int i;
OPEN_READER(re, &s->gb);
count /= 2;
if (count >= (get_bits_left(&s->gb)) / (31 * 4)) {
@ -592,8 +631,11 @@ static void decode_422_bitstream(HYuvContext *s, int count)
READ_2PIX(s->temp[0][2 * i + 1], s->temp[2][i], 2);
}
}
CLOSE_READER(re, &s->gb);
}
/* TODO instead of restarting the read when the code isn't in the first level
* of the joint table, jump into the 2nd level of the individual table. */
#define READ_2PIX_PLANE(dst0, dst1, plane){\
uint16_t code = get_vlc2(&s->gb, s->vlc[4+plane].table, VLC_BITS, 1);\
if(code != 0xffff){\
@ -663,7 +705,7 @@ static void decode_plane_bitstream(HYuvContext *s, int count, int plane)
static void decode_gray_bitstream(HYuvContext *s, int count)
{
int i;
OPEN_READER(re, &s->gb);
count/=2;
if (count >= (get_bits_left(&s->gb)) / (31 * 2)) {
@ -675,6 +717,7 @@ static void decode_gray_bitstream(HYuvContext *s, int count)
READ_2PIX(s->temp[0][2 * i], s->temp[0][2 * i + 1], 0);
}
}
CLOSE_READER(re, &s->gb);
}
static av_always_inline void decode_bgr_1(HYuvContext *s, int count,

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