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Optimize vp9_tree_probs_from_distribution

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The previous implementation visited each node in the tree multiple times
because it used each symbol's encoding to revisit the branches taken and
increment its count. Instead, we can traverse the tree depth first and
calculate the probabilities and branch counts as we walk back up. The
complexity goes from somewhere between O(nlogn) and O(n^2) (depending on
how balanced the tree is) to O(n).

Only tested one clip (256kbps, CIF), saw 13% decoding perf improvement.

Note that this optimization should port trivially to VP8 as well. In VP8,
the decoder doesn't use this function, but it does routinely show up
on the profile for realtime encoding.

Change-Id: I4f2848e4f41dc9a7694f73f3e75034bce08d1b12
This commit is contained in:
John Koleszar 2013-03-10 13:39:30 -07:00
parent 4209bba462
commit bd84685f78
6 changed files with 82 additions and 134 deletions
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5
vp9/common/vp9_entropy.c
View File

@ -292,10 +292,9 @@ static void update_coef_probs(vp9_coeff_probs *dst_coef_probs,
for (l = 0; l < PREV_COEF_CONTEXTS; ++l) {
if (l >= 3 && k == 0)
continue;
vp9_tree_probs_from_distribution(MAX_ENTROPY_TOKENS,
vp9_coef_encodings, vp9_coef_tree,
vp9_tree_probs_from_distribution(vp9_coef_tree,
coef_probs, branch_ct,
coef_counts[i][j][k][l]);
coef_counts[i][j][k][l], 0);
for (t = 0; t < ENTROPY_NODES; ++t) {
count = branch_ct[t][0] + branch_ct[t][1];
count = count > count_sat ? count_sat : count;

79
vp9/common/vp9_entropymode.c
View File

@ -302,40 +302,32 @@ struct vp9_token_struct vp9_sub_mv_ref_encoding_array[VP9_SUBMVREFS];
void vp9_init_mbmode_probs(VP9_COMMON *x) {
unsigned int bct [VP9_YMODES] [2]; /* num Ymodes > num UV modes */
vp9_tree_probs_from_distribution(VP9_YMODES, vp9_ymode_encodings,
vp9_ymode_tree, x->fc.ymode_prob,
bct, y_mode_cts);
vp9_tree_probs_from_distribution(VP9_I32X32_MODES, vp9_sb_ymode_encodings,
vp9_sb_ymode_tree, x->fc.sb_ymode_prob,
bct, y_mode_cts);
vp9_tree_probs_from_distribution(vp9_ymode_tree, x->fc.ymode_prob,
bct, y_mode_cts, 0);
vp9_tree_probs_from_distribution(vp9_sb_ymode_tree, x->fc.sb_ymode_prob,
bct, y_mode_cts, 0);
{
int i;
for (i = 0; i < 8; i++) {
vp9_tree_probs_from_distribution(VP9_YMODES, vp9_kf_ymode_encodings,
vp9_kf_ymode_tree, x->kf_ymode_prob[i],
bct, kf_y_mode_cts[i]);
vp9_tree_probs_from_distribution(VP9_I32X32_MODES,
vp9_sb_kf_ymode_encodings,
vp9_sb_kf_ymode_tree,
vp9_tree_probs_from_distribution(vp9_kf_ymode_tree, x->kf_ymode_prob[i],
bct, kf_y_mode_cts[i], 0);
vp9_tree_probs_from_distribution(vp9_sb_kf_ymode_tree,
x->sb_kf_ymode_prob[i], bct,
kf_y_mode_cts[i]);
kf_y_mode_cts[i], 0);
}
}
{
int i;
for (i = 0; i < VP9_YMODES; i++) {
vp9_tree_probs_from_distribution(VP9_UV_MODES, vp9_uv_mode_encodings,
vp9_uv_mode_tree, x->kf_uv_mode_prob[i],
bct, kf_uv_mode_cts[i]);
vp9_tree_probs_from_distribution(VP9_UV_MODES, vp9_uv_mode_encodings,
vp9_uv_mode_tree, x->fc.uv_mode_prob[i],
bct, uv_mode_cts[i]);
vp9_tree_probs_from_distribution(vp9_uv_mode_tree, x->kf_uv_mode_prob[i],
bct, kf_uv_mode_cts[i], 0);
vp9_tree_probs_from_distribution(vp9_uv_mode_tree, x->fc.uv_mode_prob[i],
bct, uv_mode_cts[i], 0);
}
}
vp9_tree_probs_from_distribution(VP9_I8X8_MODES, vp9_i8x8_mode_encodings,
vp9_i8x8_mode_tree, x->fc.i8x8_mode_prob,
bct, i8x8_mode_cts);
vp9_tree_probs_from_distribution(vp9_i8x8_mode_tree, x->fc.i8x8_mode_prob,
bct, i8x8_mode_cts, 0);
vpx_memcpy(x->fc.sub_mv_ref_prob, vp9_sub_mv_ref_prob2,
sizeof(vp9_sub_mv_ref_prob2));
@ -355,8 +347,7 @@ static void intra_bmode_probs_from_distribution(
vp9_prob p[VP9_NKF_BINTRAMODES - 1],
unsigned int branch_ct[VP9_NKF_BINTRAMODES - 1][2],
const unsigned int events[VP9_NKF_BINTRAMODES]) {
vp9_tree_probs_from_distribution(VP9_NKF_BINTRAMODES, vp9_bmode_encodings,
vp9_bmode_tree, p, branch_ct, events);
vp9_tree_probs_from_distribution(vp9_bmode_tree, p, branch_ct, events, 0);
}
void vp9_default_bmode_probs(vp9_prob p[VP9_NKF_BINTRAMODES - 1]) {
@ -368,8 +359,7 @@ static void intra_kf_bmode_probs_from_distribution(
vp9_prob p[VP9_KF_BINTRAMODES - 1],
unsigned int branch_ct[VP9_KF_BINTRAMODES - 1][2],
const unsigned int events[VP9_KF_BINTRAMODES]) {
vp9_tree_probs_from_distribution(VP9_KF_BINTRAMODES, vp9_kf_bmode_encodings,
vp9_kf_bmode_tree, p, branch_ct, events);
vp9_tree_probs_from_distribution(vp9_kf_bmode_tree, p, branch_ct, events, 0);
}
void vp9_kf_default_bmode_probs(vp9_prob p[VP9_KF_BINTRAMODES]
@ -538,17 +528,17 @@ void print_mode_contexts(VP9_COMMON *pc) {
#define MODE_COUNT_SAT 20
#define MODE_MAX_UPDATE_FACTOR 144
static void update_mode_probs(int n_modes, struct vp9_token_struct *encoding,
static void update_mode_probs(int n_modes,
const vp9_tree_index *tree, unsigned int *cnt,
vp9_prob *pre_probs, vp9_prob *dst_probs) {
vp9_prob *pre_probs, vp9_prob *dst_probs,
unsigned int tok0_offset) {
#define MAX_PROBS 32
vp9_prob probs[MAX_PROBS];
unsigned int branch_ct[MAX_PROBS][2];
int t, count, factor;
assert(n_modes - 1 < MAX_PROBS);
vp9_tree_probs_from_distribution(n_modes, encoding, tree, probs,
branch_ct, cnt);
vp9_tree_probs_from_distribution(tree, probs, branch_ct, cnt, tok0_offset);
for (t = 0; t < n_modes - 1; ++t) {
count = branch_ct[t][0] + branch_ct[t][1];
count = count > MODE_COUNT_SAT ? MODE_COUNT_SAT : count;
@ -604,31 +594,32 @@ void vp9_adapt_mode_probs(VP9_COMMON *cm) {
#endif
#endif
update_mode_probs(VP9_YMODES, vp9_ymode_encodings, vp9_ymode_tree,
update_mode_probs(VP9_YMODES, vp9_ymode_tree,
cm->fc.ymode_counts, cm->fc.pre_ymode_prob,
cm->fc.ymode_prob);
update_mode_probs(VP9_I32X32_MODES, vp9_sb_ymode_encodings, vp9_sb_ymode_tree,
cm->fc.ymode_prob, 0);
update_mode_probs(VP9_I32X32_MODES, vp9_sb_ymode_tree,
cm->fc.sb_ymode_counts, cm->fc.pre_sb_ymode_prob,
cm->fc.sb_ymode_prob);
cm->fc.sb_ymode_prob, 0);
for (i = 0; i < VP9_YMODES; ++i) {
update_mode_probs(VP9_UV_MODES, vp9_uv_mode_encodings, vp9_uv_mode_tree,
update_mode_probs(VP9_UV_MODES, vp9_uv_mode_tree,
cm->fc.uv_mode_counts[i], cm->fc.pre_uv_mode_prob[i],
cm->fc.uv_mode_prob[i]);
cm->fc.uv_mode_prob[i], 0);
}
update_mode_probs(VP9_NKF_BINTRAMODES, vp9_bmode_encodings, vp9_bmode_tree,
update_mode_probs(VP9_NKF_BINTRAMODES, vp9_bmode_tree,
cm->fc.bmode_counts, cm->fc.pre_bmode_prob,
cm->fc.bmode_prob);
update_mode_probs(VP9_I8X8_MODES, vp9_i8x8_mode_encodings,
cm->fc.bmode_prob, 0);
update_mode_probs(VP9_I8X8_MODES,
vp9_i8x8_mode_tree, cm->fc.i8x8_mode_counts,
cm->fc.pre_i8x8_mode_prob, cm->fc.i8x8_mode_prob);
cm->fc.pre_i8x8_mode_prob, cm->fc.i8x8_mode_prob, 0);
for (i = 0; i < SUBMVREF_COUNT; ++i) {
update_mode_probs(VP9_SUBMVREFS, vp9_sub_mv_ref_encoding_array,
update_mode_probs(VP9_SUBMVREFS,
vp9_sub_mv_ref_tree, cm->fc.sub_mv_ref_counts[i],
cm->fc.pre_sub_mv_ref_prob[i], cm->fc.sub_mv_ref_prob[i]);
cm->fc.pre_sub_mv_ref_prob[i], cm->fc.sub_mv_ref_prob[i],
LEFT4X4);
}
update_mode_probs(VP9_NUMMBSPLITS, vp9_mbsplit_encodings, vp9_mbsplit_tree,
update_mode_probs(VP9_NUMMBSPLITS, vp9_mbsplit_tree,
cm->fc.mbsplit_counts, cm->fc.pre_mbsplit_prob,
cm->fc.mbsplit_prob);
cm->fc.mbsplit_prob, 0);
#if CONFIG_COMP_INTERINTRA_PRED
if (cm->use_interintra) {
int factor, interintra_prob, count;

30
vp9/common/vp9_entropymv.c
View File

@ -242,29 +242,23 @@ void vp9_counts_to_nmv_context(
unsigned int (*branch_ct_hp)[2]) {
int i, j, k;
vp9_counts_process(NMVcount, usehp);
vp9_tree_probs_from_distribution(MV_JOINTS,
vp9_mv_joint_encodings,
vp9_mv_joint_tree,
vp9_tree_probs_from_distribution(vp9_mv_joint_tree,
prob->joints,
branch_ct_joint,
NMVcount->joints);
NMVcount->joints, 0);
for (i = 0; i < 2; ++i) {
prob->comps[i].sign = get_binary_prob(NMVcount->comps[i].sign[0],
NMVcount->comps[i].sign[1]);
branch_ct_sign[i][0] = NMVcount->comps[i].sign[0];
branch_ct_sign[i][1] = NMVcount->comps[i].sign[1];
vp9_tree_probs_from_distribution(MV_CLASSES,
vp9_mv_class_encodings,
vp9_mv_class_tree,
vp9_tree_probs_from_distribution(vp9_mv_class_tree,
prob->comps[i].classes,
branch_ct_classes[i],
NMVcount->comps[i].classes);
vp9_tree_probs_from_distribution(CLASS0_SIZE,
vp9_mv_class0_encodings,
vp9_mv_class0_tree,
NMVcount->comps[i].classes, 0);
vp9_tree_probs_from_distribution(vp9_mv_class0_tree,
prob->comps[i].class0,
branch_ct_class0[i],
NMVcount->comps[i].class0);
NMVcount->comps[i].class0, 0);
for (j = 0; j < MV_OFFSET_BITS; ++j) {
prob->comps[i].bits[j] = get_binary_prob(NMVcount->comps[i].bits[j][0],
NMVcount->comps[i].bits[j][1]);
@ -274,19 +268,15 @@ void vp9_counts_to_nmv_context(
}
for (i = 0; i < 2; ++i) {
for (k = 0; k < CLASS0_SIZE; ++k) {
vp9_tree_probs_from_distribution(4,
vp9_mv_fp_encodings,
vp9_mv_fp_tree,
vp9_tree_probs_from_distribution(vp9_mv_fp_tree,
prob->comps[i].class0_fp[k],
branch_ct_class0_fp[i][k],
NMVcount->comps[i].class0_fp[k]);
NMVcount->comps[i].class0_fp[k], 0);
}
vp9_tree_probs_from_distribution(4,
vp9_mv_fp_encodings,
vp9_mv_fp_tree,
vp9_tree_probs_from_distribution(vp9_mv_fp_tree,
prob->comps[i].fp,
branch_ct_fp[i],
NMVcount->comps[i].fp);
NMVcount->comps[i].fp, 0);
}
if (usehp) {
for (i = 0; i < 2; ++i) {

81
vp9/common/vp9_treecoder.c
View File

@ -48,66 +48,37 @@ void vp9_tokens_from_tree_offset(struct vp9_token_struct *p, vp9_tree t,
tree2tok(p - offset, t, 0, 0, 0);
}
static void branch_counts(
int n, /* n = size of alphabet */
vp9_token tok [ /* n */ ],
vp9_tree tree,
unsigned int branch_ct [ /* n-1 */ ] [2],
const unsigned int num_events[ /* n */ ]
) {
const int tree_len = n - 1;
int t = 0;
#if CONFIG_DEBUG
assert(tree_len);
#endif
do {
branch_ct[t][0] = branch_ct[t][1] = 0;
} while (++t < tree_len);
t = 0;
do {
int L = tok[t].Len;
const int enc = tok[t].value;
const unsigned int ct = num_events[t];
vp9_tree_index i = 0;
do {
const int b = (enc >> --L) & 1;
const int j = i >> 1;
#if CONFIG_DEBUG
assert(j < tree_len && 0 <= L);
#endif
branch_ct [j] [b] += ct;
i = tree[ i + b];
} while (i > 0);
#if CONFIG_DEBUG
assert(!L);
#endif
} while (++t < n);
static unsigned int convert_distribution(unsigned int i,
vp9_tree tree,
vp9_prob probs[],
unsigned int branch_ct[][2],
const unsigned int num_events[],
unsigned int tok0_offset) {
unsigned int left, right;
if (tree[i] <= 0) {
left = num_events[-tree[i] - tok0_offset];
} else {
left = convert_distribution(tree[i], tree, probs, branch_ct,
num_events, tok0_offset);
}
if (tree[i + 1] <= 0) {
right = num_events[-tree[i + 1] - tok0_offset];
} else {
right = convert_distribution(tree[i + 1], tree, probs, branch_ct,
num_events, tok0_offset);
}
probs[i>>1] = get_binary_prob(left, right);
branch_ct[i>>1][0] = left;
branch_ct[i>>1][1] = right;
return left + right;
}
void vp9_tree_probs_from_distribution(
int n, /* n = size of alphabet */
vp9_token tok [ /* n */ ],
vp9_tree tree,
vp9_prob probs [ /* n-1 */ ],
unsigned int branch_ct [ /* n-1 */ ] [2],
const unsigned int num_events[ /* n */ ]
) {
const int tree_len = n - 1;
int t = 0;
branch_counts(n, tok, tree, branch_ct, num_events);
do {
probs[t] = get_binary_prob(branch_ct[t][0], branch_ct[t][1]);
} while (++t < tree_len);
const unsigned int num_events[ /* n */ ],
unsigned int tok0_offset) {
convert_distribution(0, tree, probs, branch_ct, num_events, tok0_offset);
}

7
vp9/common/vp9_treecoder.h
View File

@ -47,12 +47,11 @@ void vp9_tokens_from_tree_offset(struct vp9_token_struct *, vp9_tree,
taken for each node on the tree; this facilitiates decisions as to
probability updates. */
void vp9_tree_probs_from_distribution(int n, /* n = size of alphabet */
vp9_token tok[ /* n */ ],
vp9_tree tree,
void vp9_tree_probs_from_distribution(vp9_tree tree,
vp9_prob probs[ /* n - 1 */ ],
unsigned int branch_ct[ /* n - 1 */ ][2],
const unsigned int num_events[ /* n */ ]);
const unsigned int num_events[ /* n */ ],
unsigned int tok0_offset);
static INLINE vp9_prob clip_prob(int p) {
return (p > 255) ? 255u : (p < 1) ? 1u : p;

14
vp9/encoder/vp9_bitstream.c
View File

@ -110,8 +110,8 @@ static void update_mode(
unsigned int new_b = 0, old_b = 0;
int i = 0;
vp9_tree_probs_from_distribution(n--, tok, tree,
Pnew, bct, num_events);
vp9_tree_probs_from_distribution(tree, Pnew, bct, num_events, 0);
n--;
do {
new_b += cost_branch(bct[i], Pnew[i]);
@ -167,10 +167,9 @@ static void update_switchable_interp_probs(VP9_COMP *cpi,
int i, j;
for (j = 0; j <= VP9_SWITCHABLE_FILTERS; ++j) {
vp9_tree_probs_from_distribution(
VP9_SWITCHABLE_FILTERS,
vp9_switchable_interp_encodings, vp9_switchable_interp_tree,
vp9_switchable_interp_tree,
pc->fc.switchable_interp_prob[j], branch_ct,
cpi->switchable_interp_count[j]);
cpi->switchable_interp_count[j], 0);
for (i = 0; i < VP9_SWITCHABLE_FILTERS - 1; ++i) {
if (pc->fc.switchable_interp_prob[j][i] < 1)
pc->fc.switchable_interp_prob[j][i] = 1;
@ -1189,11 +1188,10 @@ static void build_tree_distribution(vp9_coeff_probs *coef_probs,
for (l = 0; l < PREV_COEF_CONTEXTS; ++l) {
if (l >= 3 && k == 0)
continue;
vp9_tree_probs_from_distribution(MAX_ENTROPY_TOKENS,
vp9_coef_encodings, vp9_coef_tree,
vp9_tree_probs_from_distribution(vp9_coef_tree,
coef_probs[i][j][k][l],
coef_branch_ct[i][j][k][l],
coef_counts[i][j][k][l]);
coef_counts[i][j][k][l], 0);
#ifdef ENTROPY_STATS
if (!cpi->dummy_packing)
for (t = 0; t < MAX_ENTROPY_TOKENS; ++t)