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Simplify Segment Coding

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Remove top node optimization.
The improvement this gives is not sufficient to justify
the extra complexity.

Change-Id: I2bb4a12a50ffd52cacfa4a3e8acbb2e522066905
This commit is contained in:
Paul Wilkins
2013-04-24 10:20:52 +01:00
parent 27bb4777cd
commit c77aff1286
5 changed files with 8 additions and 77 deletions
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30
vp9/encoder/vp9_segmentation.c
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@@ -103,8 +103,7 @@ static int cost_segmap(MACROBLOCKD *xd,
// Based on set of segment counts calculate a probability tree
static void calc_segtree_probs_pred(MACROBLOCKD *xd,
int (*segcounts)[MAX_MB_SEGMENTS],
vp9_prob *segment_tree_probs,
vp9_prob *mod_probs) {
vp9_prob *segment_tree_probs) {
int count[4];
assert(!segcounts[0][0] && !segcounts[1][1] &&
@@ -121,24 +120,12 @@ static void calc_segtree_probs_pred(MACROBLOCKD *xd,
count[2] + count[3]);
segment_tree_probs[1] = get_binary_prob(count[0], count[1]);
segment_tree_probs[2] = get_binary_prob(count[2], count[3]);
// now work out modified counts that the decoder would have
count[0] = segment_tree_probs[0] * segment_tree_probs[1];
count[1] = segment_tree_probs[0] * (256 - segment_tree_probs[1]);
count[2] = (256 - segment_tree_probs[0]) * segment_tree_probs[2];
count[3] = (256 - segment_tree_probs[0]) * (256 - segment_tree_probs[2]);
// Work out modified probabilties depending on what segment was predicted
mod_probs[0] = get_binary_prob(count[1], count[2] + count[3]);
mod_probs[1] = get_binary_prob(count[0], count[2] + count[3]);
mod_probs[2] = get_binary_prob(count[0] + count[1], count[3]);
mod_probs[3] = get_binary_prob(count[0] + count[1], count[2]);
}
// Based on set of segment counts and probabilities calculate a cost estimate
static int cost_segmap_pred(MACROBLOCKD *xd,
int (*segcounts)[MAX_MB_SEGMENTS],
vp9_prob *probs, vp9_prob *mod_probs) {
vp9_prob *probs) {
int pred_seg, cost = 0;
for (pred_seg = 0; pred_seg < MAX_MB_SEGMENTS; pred_seg++) {
@@ -147,8 +134,8 @@ static int cost_segmap_pred(MACROBLOCKD *xd,
// Cost the top node of the tree
count1 = segcounts[pred_seg][0] + segcounts[pred_seg][1];
count2 = segcounts[pred_seg][2] + segcounts[pred_seg][3];
cost += count1 * vp9_cost_zero(mod_probs[pred_seg]) +
count2 * vp9_cost_one(mod_probs[pred_seg]);
cost += count1 * vp9_cost_zero(probs[0]) +
count2 * vp9_cost_one(probs[0]);
// Now add the cost of each individual segment branch
if (pred_seg >= 2 && count1) {
@@ -217,7 +204,6 @@ void vp9_choose_segmap_coding_method(VP9_COMP *cpi) {
vp9_prob no_pred_tree[MB_FEATURE_TREE_PROBS];
vp9_prob t_pred_tree[MB_FEATURE_TREE_PROBS];
vp9_prob t_pred_tree_mod[MAX_MB_SEGMENTS];
vp9_prob t_nopred_prob[PREDICTION_PROBS];
const int mis = cm->mode_info_stride;
@@ -332,10 +318,8 @@ void vp9_choose_segmap_coding_method(VP9_COMP *cpi) {
if (cm->frame_type != KEY_FRAME) {
// Work out probability tree for coding those segments not
// predicted using the temporal method and the cost.
calc_segtree_probs_pred(xd, t_unpred_seg_counts, t_pred_tree,
t_pred_tree_mod);
t_pred_cost = cost_segmap_pred(xd, t_unpred_seg_counts, t_pred_tree,
t_pred_tree_mod);
calc_segtree_probs_pred(xd, t_unpred_seg_counts, t_pred_tree);
t_pred_cost = cost_segmap_pred(xd, t_unpred_seg_counts, t_pred_tree);
// Add in the cost of the signalling for each prediction context
for (i = 0; i < PREDICTION_PROBS; i++) {
@@ -355,8 +339,6 @@ void vp9_choose_segmap_coding_method(VP9_COMP *cpi) {
cm->temporal_update = 1;
vpx_memcpy(xd->mb_segment_tree_probs,
t_pred_tree, sizeof(t_pred_tree));
vpx_memcpy(xd->mb_segment_mispred_tree_probs,
t_pred_tree_mod, sizeof(t_pred_tree_mod));
vpx_memcpy(&cm->segment_pred_probs,
t_nopred_prob, sizeof(t_nopred_prob));
} else {