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VP8: unroll MB mode decoding tree 

~50% faster MB mode decoding, plus eliminate a costly switch.

Originally committed as revision 24679 to svn://svn.ffmpeg.org/ffmpeg/trunk
This commit is contained in:
Jason Garrett-Glaser 2010-08-03 10:24:28 +00:00
parent be665c7da6
commit 23117d69c1
2 changed files with 23 additions and 31 deletions
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47
libavcodec/vp8.c
View File

@ -745,7 +745,6 @@ void decode_mb_mode(VP8Context *s, VP8Macroblock *mb, int mb_x, int mb_y, uint8_
} else if (vp56_rac_get_prob_branchy(c, s->prob->intra)) {
VP56mv near[2], best;
uint8_t cnt[4] = { 0 };
uint8_t p[4];
// inter MB, 16.2
if (vp56_rac_get_prob_branchy(c, s->prob->last))
@ -757,30 +756,30 @@ void decode_mb_mode(VP8Context *s, VP8Macroblock *mb, int mb_x, int mb_y, uint8_
// motion vectors, 16.3
find_near_mvs(s, mb, mb_x, mb_y, near, &best, cnt);
p[0] = vp8_mode_contexts[cnt[0]][0];
p[1] = vp8_mode_contexts[cnt[1]][1];
p[2] = vp8_mode_contexts[cnt[2]][2];
p[3] = vp8_mode_contexts[cnt[3]][3];
mb->mode = vp8_rac_get_tree(c, vp8_pred16x16_tree_mvinter, p);
switch (mb->mode) {
case VP8_MVMODE_SPLIT:
clamp_mv(s, &mb->mv, &mb->mv, mb_x, mb_y);
mb->mv = mb->bmv[decode_splitmvs(s, c, mb) - 1];
break;
case VP8_MVMODE_ZERO:
if (vp56_rac_get_prob_branchy(c, vp8_mode_contexts[cnt[0]][0])) {
if (vp56_rac_get_prob_branchy(c, vp8_mode_contexts[cnt[1]][1])) {
if (vp56_rac_get_prob_branchy(c, vp8_mode_contexts[cnt[2]][2])) {
if (vp56_rac_get_prob_branchy(c, vp8_mode_contexts[cnt[3]][3])) {
mb->mode = VP8_MVMODE_SPLIT;
clamp_mv(s, &mb->mv, &mb->mv, mb_x, mb_y);
mb->mv = mb->bmv[decode_splitmvs(s, c, mb) - 1];
} else {
mb->mode = VP8_MVMODE_NEW;
clamp_mv(s, &mb->mv, &mb->mv, mb_x, mb_y);
mb->mv.y += + read_mv_component(c, s->prob->mvc[0]);
mb->mv.x += + read_mv_component(c, s->prob->mvc[1]);
}
} else {
mb->mode = VP8_MVMODE_NEAR;
clamp_mv(s, &mb->mv, &near[1], mb_x, mb_y);
}
} else {
mb->mode = VP8_MVMODE_NEAREST;
clamp_mv(s, &mb->mv, &near[0], mb_x, mb_y);
}
} else {
mb->mode = VP8_MVMODE_ZERO;
AV_ZERO32(&mb->mv);
break;
case VP8_MVMODE_NEAREST:
clamp_mv(s, &mb->mv, &near[0], mb_x, mb_y);
break;
case VP8_MVMODE_NEAR:
clamp_mv(s, &mb->mv, &near[1], mb_x, mb_y);
break;
case VP8_MVMODE_NEW:
clamp_mv(s, &mb->mv, &mb->mv, mb_x, mb_y);
mb->mv.y += + read_mv_component(c, s->prob->mvc[0]);
mb->mv.x += + read_mv_component(c, s->prob->mvc[1]);
break;
}
if (mb->mode != VP8_MVMODE_SPLIT) {
mb->partitioning = VP8_SPLITMVMODE_NONE;

7
libavcodec/vp8data.h
View File

@ -103,13 +103,6 @@ static const int vp8_mode_contexts[6][4] = {
{ 234, 188, 128, 28 },
};
static const int8_t vp8_pred16x16_tree_mvinter[4][2] = {
{ -VP8_MVMODE_ZERO, 1 }, // '0'
{ -VP8_MVMODE_NEAREST, 2 }, // '10'
{ -VP8_MVMODE_NEAR, 3 }, // '110'
{ -VP8_MVMODE_NEW, -VP8_MVMODE_SPLIT } // '1110', '1111'
};
static const uint8_t vp8_mbsplits[5][16] = {
{ 0, 0, 0, 0, 0, 0, 0, 0,
1, 1, 1, 1, 1, 1, 1, 1 },