vpx/vp8/common/pred_common.c
Ronald S. Bultje 5d4cffb35f Superblock coding.
This commit adds a pick_sb_mode() function which selects the best 32x32
superblock coding mode. Then it selects the best per-MB modes, compares
the two and encodes that in the bitstream.

The bitstream coding is rather simplistic right now. At the SB level,
we code a bit to indicate whether this block uses SB-coding (32x32
prediction) or MB-coding (anything else), and then we follow with the
actual modes. This could and should be modified in the future, but is
omitted from this commit because it will likely involve reorganizing
much more code rather than just adding SB coding, so it's better to let
that be judged on its own merits.

Gains on derf: about even, YT/HD: +0.75%, STD/HD: +1.5%.

Change-Id: Iae313a7cbd8f75b3c66d04a68b991cb096eaaba6
2012-08-20 14:43:34 -07:00

425 lines
13 KiB
C

/*
* Copyright (c) 2012 The WebM project authors. All Rights Reserved.
*
* Use of this source code is governed by a BSD-style license
* that can be found in the LICENSE file in the root of the source
* tree. An additional intellectual property rights grant can be found
* in the file PATENTS. All contributing project authors may
* be found in the AUTHORS file in the root of the source tree.
*/
#include "vp8/common/pred_common.h"
#include "vp8/common/seg_common.h"
// TBD prediction functions for various bitstream signals
// Returns a context number for the given MB prediction signal
unsigned char get_pred_context(VP8_COMMON *const cm,
MACROBLOCKD *const xd,
PRED_ID pred_id) {
int pred_context;
MODE_INFO *m = xd->mode_info_context;
// Note:
// The mode info data structure has a one element border above and to the
// left of the entries correpsonding to real macroblocks.
// The prediction flags in these dummy entries are initialised to 0.
switch (pred_id) {
case PRED_SEG_ID:
pred_context = (m - 1)->mbmi.seg_id_predicted +
(m - cm->mode_info_stride)->mbmi.seg_id_predicted;
break;
case PRED_REF:
pred_context = (m - 1)->mbmi.ref_predicted +
(m - cm->mode_info_stride)->mbmi.ref_predicted;
break;
case PRED_COMP:
// Context based on use of comp pred flag by neighbours
// pred_context =
// ((m - 1)->mbmi.second_ref_frame != INTRA_FRAME) +
// ((m - cm->mode_info_stride)->mbmi.second_ref_frame != INTRA_FRAME);
// Context based on mode and reference frame
// if ( m->mbmi.ref_frame == LAST_FRAME )
// pred_context = 0 + (m->mbmi.mode != ZEROMV);
// else if ( m->mbmi.ref_frame == GOLDEN_FRAME )
// pred_context = 2 + (m->mbmi.mode != ZEROMV);
// else
// pred_context = 4 + (m->mbmi.mode != ZEROMV);
if (m->mbmi.ref_frame == LAST_FRAME)
pred_context = 0;
else
pred_context = 1;
break;
case PRED_MBSKIP:
pred_context = (m - 1)->mbmi.mb_skip_coeff +
(m - cm->mode_info_stride)->mbmi.mb_skip_coeff;
break;
#if CONFIG_SWITCHABLE_INTERP
case PRED_SWITCHABLE_INTERP:
{
int left_in_image = (m - 1)->mbmi.mb_in_image;
int above_in_image = (m - cm->mode_info_stride)->mbmi.mb_in_image;
int left_mode = (m - 1)->mbmi.mode;
int above_mode = (m - cm->mode_info_stride)->mbmi.mode;
int left_interp, above_interp;
if (left_in_image && left_mode >= NEARESTMV && left_mode <= SPLITMV)
left_interp = vp8_switchable_interp_map[(m - 1)->mbmi.interp_filter];
else
left_interp = VP8_SWITCHABLE_FILTERS;
if (above_in_image && above_mode >= NEARESTMV && above_mode <= SPLITMV)
above_interp = vp8_switchable_interp_map[
(m - cm->mode_info_stride)->mbmi.interp_filter];
else
above_interp = VP8_SWITCHABLE_FILTERS;
if (left_interp == above_interp)
pred_context = left_interp;
else if (left_interp == VP8_SWITCHABLE_FILTERS &&
above_interp != VP8_SWITCHABLE_FILTERS)
pred_context = above_interp;
else if (left_interp != VP8_SWITCHABLE_FILTERS &&
above_interp == VP8_SWITCHABLE_FILTERS)
pred_context = left_interp;
else
pred_context = VP8_SWITCHABLE_FILTERS;
}
break;
#endif
default:
// TODO *** add error trap code.
pred_context = 0;
break;
}
return pred_context;
}
// This function returns a context probability for coding a given
// prediction signal
vp8_prob get_pred_prob(VP8_COMMON *const cm,
MACROBLOCKD *const xd,
PRED_ID pred_id) {
vp8_prob pred_probability;
int pred_context;
// Get the appropriate prediction context
pred_context = get_pred_context(cm, xd, pred_id);
switch (pred_id) {
case PRED_SEG_ID:
pred_probability = cm->segment_pred_probs[pred_context];
break;
case PRED_REF:
pred_probability = cm->ref_pred_probs[pred_context];
break;
case PRED_COMP:
// In keeping with convention elsewhre the probability returned is
// the probability of a "0" outcome which in this case means the
// probability of comp pred off.
pred_probability = cm->prob_comppred[pred_context];
break;
case PRED_MBSKIP:
pred_probability = cm->mbskip_pred_probs[pred_context];
break;
default:
// TODO *** add error trap code.
pred_probability = 128;
break;
}
return pred_probability;
}
// This function returns a context probability ptr for coding a given
// prediction signal
vp8_prob *get_pred_probs(VP8_COMMON *const cm,
MACROBLOCKD *const xd,
PRED_ID pred_id) {
vp8_prob *pred_probability;
int pred_context;
// Get the appropriate prediction context
pred_context = get_pred_context(cm, xd, pred_id);
switch (pred_id) {
case PRED_SEG_ID:
pred_probability = &cm->segment_pred_probs[pred_context];
break;
case PRED_REF:
pred_probability = &cm->ref_pred_probs[pred_context];
break;
case PRED_COMP:
// In keeping with convention elsewhre the probability returned is
// the probability of a "0" outcome which in this case means the
// probability of comp pred off.
pred_probability = &cm->prob_comppred[pred_context];
break;
case PRED_MBSKIP:
pred_probability = &cm->mbskip_pred_probs[pred_context];
break;
#if CONFIG_SWITCHABLE_INTERP
case PRED_SWITCHABLE_INTERP:
pred_probability = &cm->fc.switchable_interp_prob[pred_context][0];
break;
#endif
default:
// TODO *** add error trap code.
pred_probability = NULL;
break;
}
return pred_probability;
}
// This function returns the status of the given prediction signal.
// I.e. is the predicted value for the given signal correct.
unsigned char get_pred_flag(MACROBLOCKD *const xd,
PRED_ID pred_id) {
unsigned char pred_flag = 0;
switch (pred_id) {
case PRED_SEG_ID:
pred_flag = xd->mode_info_context->mbmi.seg_id_predicted;
break;
case PRED_REF:
pred_flag = xd->mode_info_context->mbmi.ref_predicted;
break;
case PRED_MBSKIP:
pred_flag = xd->mode_info_context->mbmi.mb_skip_coeff;
break;
default:
// TODO *** add error trap code.
pred_flag = 0;
break;
}
return pred_flag;
}
// This function sets the status of the given prediction signal.
// I.e. is the predicted value for the given signal correct.
void set_pred_flag(MACROBLOCKD *const xd,
PRED_ID pred_id,
unsigned char pred_flag) {
switch (pred_id) {
case PRED_SEG_ID:
xd->mode_info_context->mbmi.seg_id_predicted = pred_flag;
#if CONFIG_SUPERBLOCKS
if (xd->mode_info_context->mbmi.encoded_as_sb) {
xd->mode_info_context[1].mbmi.seg_id_predicted = pred_flag;
xd->mode_info_context[xd->mode_info_stride].mbmi.seg_id_predicted = pred_flag;
xd->mode_info_context[xd->mode_info_stride+1].mbmi.seg_id_predicted = pred_flag;
}
#endif
break;
case PRED_REF:
xd->mode_info_context->mbmi.ref_predicted = pred_flag;
#if CONFIG_SUPERBLOCKS
if (xd->mode_info_context->mbmi.encoded_as_sb) {
xd->mode_info_context[1].mbmi.ref_predicted = pred_flag;
xd->mode_info_context[xd->mode_info_stride].mbmi.ref_predicted = pred_flag;
xd->mode_info_context[xd->mode_info_stride+1].mbmi.ref_predicted = pred_flag;
}
#endif
break;
case PRED_MBSKIP:
xd->mode_info_context->mbmi.mb_skip_coeff = pred_flag;
break;
default:
// TODO *** add error trap code.
break;
}
}
// The following contain the guts of the prediction code used to
// peredict various bitstream signals.
// Macroblock segment id prediction function
unsigned char get_pred_mb_segid(VP8_COMMON *const cm, int MbIndex) {
// Currently the prediction for the macroblock segment ID is
// the value stored for this macroblock in the previous frame.
return cm->last_frame_seg_map[MbIndex];
}
MV_REFERENCE_FRAME get_pred_ref(VP8_COMMON *const cm,
MACROBLOCKD *const xd) {
MODE_INFO *m = xd->mode_info_context;
MV_REFERENCE_FRAME left;
MV_REFERENCE_FRAME above;
MV_REFERENCE_FRAME above_left;
MV_REFERENCE_FRAME pred_ref = LAST_FRAME;
int segment_id = xd->mode_info_context->mbmi.segment_id;
int seg_ref_active;
int i;
unsigned char frame_allowed[MAX_REF_FRAMES] = {1, 1, 1, 1};
unsigned char ref_score[MAX_REF_FRAMES];
unsigned char best_score = 0;
unsigned char left_in_image;
unsigned char above_in_image;
unsigned char above_left_in_image;
// Is segment coding ennabled
seg_ref_active = segfeature_active(xd, segment_id, SEG_LVL_REF_FRAME);
// Special case treatment if segment coding is enabled.
// Dont allow prediction of a reference frame that the segment
// does not allow
if (seg_ref_active) {
for (i = 0; i < MAX_REF_FRAMES; i++) {
frame_allowed[i] =
check_segref(xd, segment_id, i);
// Score set to 0 if ref frame not allowed
ref_score[i] = cm->ref_scores[i] * frame_allowed[i];
}
} else
vpx_memcpy(ref_score, cm->ref_scores, sizeof(ref_score));
// Reference frames used by neighbours
left = (m - 1)->mbmi.ref_frame;
above = (m - cm->mode_info_stride)->mbmi.ref_frame;
above_left = (m - 1 - cm->mode_info_stride)->mbmi.ref_frame;
// Are neighbours in image
left_in_image = (m - 1)->mbmi.mb_in_image;
above_in_image = (m - cm->mode_info_stride)->mbmi.mb_in_image;
above_left_in_image = (m - 1 - cm->mode_info_stride)->mbmi.mb_in_image;
// Adjust scores for candidate reference frames based on neigbours
if (frame_allowed[left] && left_in_image) {
ref_score[left] += 16;
if (above_left_in_image && (left == above_left))
ref_score[left] += 4;
}
if (frame_allowed[above] && above_in_image) {
ref_score[above] += 16;
if (above_left_in_image && (above == above_left))
ref_score[above] += 4;
}
// Now choose the candidate with the highest score
for (i = 0; i < MAX_REF_FRAMES; i++) {
if (ref_score[i] > best_score) {
pred_ref = i;
best_score = ref_score[i];
}
}
return pred_ref;
}
// Functions to computes a set of modified reference frame probabilities
// to use when the prediction of the reference frame value fails
void calc_ref_probs(int *count, vp8_prob *probs) {
int tot_count;
tot_count = count[0] + count[1] + count[2] + count[3];
if (tot_count) {
probs[0] = (vp8_prob)((count[0] * 255 + (tot_count >> 1)) / tot_count);
probs[0] += !probs[0];
} else
probs[0] = 128;
tot_count -= count[0];
if (tot_count) {
probs[1] = (vp8_prob)((count[1] * 255 + (tot_count >> 1)) / tot_count);
probs[1] += !probs[1];
} else
probs[1] = 128;
tot_count -= count[1];
if (tot_count) {
probs[2] = (vp8_prob)((count[2] * 255 + (tot_count >> 1)) / tot_count);
probs[2] += !probs[2];
} else
probs[2] = 128;
}
// Computes a set of modified conditional probabilities for the reference frame
// Values willbe set to 0 for reference frame options that are not possible
// because wither they were predicted and prediction has failed or because
// they are not allowed for a given segment.
void compute_mod_refprobs(VP8_COMMON *const cm) {
int norm_cnt[MAX_REF_FRAMES];
int intra_count;
int inter_count;
int last_count;
int gfarf_count;
int gf_count;
int arf_count;
intra_count = cm->prob_intra_coded;
inter_count = (255 - intra_count);
last_count = (inter_count * cm->prob_last_coded) / 255;
gfarf_count = inter_count - last_count;
gf_count = (gfarf_count * cm->prob_gf_coded) / 255;
arf_count = gfarf_count - gf_count;
// Work out modified reference frame probabilities to use where prediction
// of the reference frame fails
norm_cnt[0] = 0;
norm_cnt[1] = last_count;
norm_cnt[2] = gf_count;
norm_cnt[3] = arf_count;
calc_ref_probs(norm_cnt, cm->mod_refprobs[INTRA_FRAME]);
cm->mod_refprobs[INTRA_FRAME][0] = 0; // This branch implicit
norm_cnt[0] = intra_count;
norm_cnt[1] = 0;
norm_cnt[2] = gf_count;
norm_cnt[3] = arf_count;
calc_ref_probs(norm_cnt, cm->mod_refprobs[LAST_FRAME]);
cm->mod_refprobs[LAST_FRAME][1] = 0; // This branch implicit
norm_cnt[0] = intra_count;
norm_cnt[1] = last_count;
norm_cnt[2] = 0;
norm_cnt[3] = arf_count;
calc_ref_probs(norm_cnt, cm->mod_refprobs[GOLDEN_FRAME]);
cm->mod_refprobs[GOLDEN_FRAME][2] = 0; // This branch implicit
norm_cnt[0] = intra_count;
norm_cnt[1] = last_count;
norm_cnt[2] = gf_count;
norm_cnt[3] = 0;
calc_ref_probs(norm_cnt, cm->mod_refprobs[ALTREF_FRAME]);
cm->mod_refprobs[ALTREF_FRAME][2] = 0; // This branch implicit
// Score the reference frames based on overal frequency.
// These scores contribute to the prediction choices.
// Max score 17 min 1
cm->ref_scores[INTRA_FRAME] = 1 + (intra_count * 16 / 255);
cm->ref_scores[LAST_FRAME] = 1 + (last_count * 16 / 255);
cm->ref_scores[GOLDEN_FRAME] = 1 + (gf_count * 16 / 255);
cm->ref_scores[ALTREF_FRAME] = 1 + (arf_count * 16 / 255);
}