vpx/vp8/encoder/segmentation.c
Paul Wilkins 661b2c2dcf Further work on Segmentation Experiment:
This check in includes quite a lot of clean up and refactoring.

Most of the analysis and set up for the different coding options for the
segment map (currently simple distribution based coding or temporaly
predicted coding), has been moved to one location (the function
choose_segmap_coding_method() in segmenation.c). This code was previously
scattered around in various locations making integration with other
experiments and modification / debug more difficult.

Currently the functionality is as it was with the exception that the
prediction probabilities are now only transmitted when the temporal
prediction mode is selected.

There is still quite a bit more clean up work that will be possible
when the #ifdef is removed. Also at that time I may rename and alter
the sense of macroblock based variable "segment_flag" which indicates
(1 that the segmnet id is not predicted vs 0 that it is predicted).

I also intend to experiment with a spatial prediction mode that can be
used when coding a key frame segment map or in cases where temporal
prediction does not work well but there is spatial correlation.

In a later check in when the ifdefs have gone I may also move the call
to choose_segmap_coding_method() to just before where the bitsream is
packed (currently it is in vp8_encode_frame()) to further reduce the
possibility of clashes with other experiments and prevent it being called
on each itteration of the recode loop.

Change-Id: I3d4aba2a2826ec21f367678d5b07c1d1c36db168
2011-11-15 11:13:33 +00:00

325 lines
11 KiB
C

/*
* Copyright (c) 2010 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 "segmentation.h"
#include "vpx_mem/vpx_mem.h"
void vp8_update_gf_useage_maps(VP8_COMP *cpi, VP8_COMMON *cm, MACROBLOCK *x)
{
int mb_row, mb_col;
MODE_INFO *this_mb_mode_info = cm->mi;
x->gf_active_ptr = (signed char *)cpi->gf_active_flags;
if ((cm->frame_type == KEY_FRAME) || (cm->refresh_golden_frame))
{
// Reset Gf useage monitors
vpx_memset(cpi->gf_active_flags, 1, (cm->mb_rows * cm->mb_cols));
cpi->gf_active_count = cm->mb_rows * cm->mb_cols;
}
else
{
// for each macroblock row in image
for (mb_row = 0; mb_row < cm->mb_rows; mb_row++)
{
// for each macroblock col in image
for (mb_col = 0; mb_col < cm->mb_cols; mb_col++)
{
// If using golden then set GF active flag if not already set.
// If using last frame 0,0 mode then leave flag as it is
// else if using non 0,0 motion or intra modes then clear
// flag if it is currently set
if ((this_mb_mode_info->mbmi.ref_frame == GOLDEN_FRAME) ||
(this_mb_mode_info->mbmi.ref_frame == ALTREF_FRAME))
{
if (*(x->gf_active_ptr) == 0)
{
*(x->gf_active_ptr) = 1;
cpi->gf_active_count ++;
}
}
else if ((this_mb_mode_info->mbmi.mode != ZEROMV) &&
*(x->gf_active_ptr))
{
*(x->gf_active_ptr) = 0;
cpi->gf_active_count--;
}
x->gf_active_ptr++; // Step onto next entry
this_mb_mode_info++; // skip to next mb
}
// this is to account for the border
this_mb_mode_info++;
}
}
}
void vp8_enable_segmentation(VP8_PTR ptr)
{
VP8_COMP *cpi = (VP8_COMP *)(ptr);
// Set the appropriate feature bit
cpi->mb.e_mbd.segmentation_enabled = 1;
cpi->mb.e_mbd.update_mb_segmentation_map = 1;
cpi->mb.e_mbd.update_mb_segmentation_data = 1;
}
void vp8_disable_segmentation(VP8_PTR ptr)
{
VP8_COMP *cpi = (VP8_COMP *)(ptr);
// Clear the appropriate feature bit
cpi->mb.e_mbd.segmentation_enabled = 0;
}
void vp8_set_segmentation_map(VP8_PTR ptr,
unsigned char *segmentation_map)
{
VP8_COMP *cpi = (VP8_COMP *)(ptr);
// Copy in the new segmentation map
vpx_memcpy( cpi->segmentation_map, segmentation_map,
(cpi->common.mb_rows * cpi->common.mb_cols) );
// Signal that the map should be updated.
cpi->mb.e_mbd.update_mb_segmentation_map = 1;
cpi->mb.e_mbd.update_mb_segmentation_data = 1;
}
void vp8_set_segment_data(VP8_PTR ptr,
signed char *feature_data,
unsigned char abs_delta)
{
VP8_COMP *cpi = (VP8_COMP *)(ptr);
cpi->mb.e_mbd.mb_segement_abs_delta = abs_delta;
vpx_memcpy(cpi->mb.e_mbd.segment_feature_data, feature_data,
sizeof(cpi->mb.e_mbd.segment_feature_data));
//#if CONFIG_SEGFEATURES
// TBD ?? Set the feature mask
// vpx_memcpy(cpi->mb.e_mbd.segment_feature_mask, 0,
// sizeof(cpi->mb.e_mbd.segment_feature_mask));
}
#if CONFIG_SEGMENTATION
// Based on set of segment counts calculate a probability tree
void calc_segtree_probs( MACROBLOCKD * xd,
int * segcounts,
vp8_prob * segment_tree_probs )
{
int count1,count2;
int tot_count;
int i;
// Blank the strtucture to start with
vpx_memset(segment_tree_probs, 0, sizeof(segment_tree_probs));
// Total count for all segments
count1 = segcounts[0] + segcounts[1];
count2 = segcounts[2] + segcounts[3];
tot_count = count1 + count2;
// Work out probabilities of each segment
if (tot_count)
segment_tree_probs[0] = (count1 * 255) / tot_count;
if (count1 > 0)
segment_tree_probs[1] = (segcounts[0] * 255) / count1;
if (count2 > 0)
segment_tree_probs[2] = (segcounts[2] * 255) / count2;
// Clamp probabilities to minimum allowed value
for (i = 0; i < MB_FEATURE_TREE_PROBS; i++)
{
if (segment_tree_probs[i] == 0)
segment_tree_probs[i] = 1;
}
}
// Based on set of segment counts and probabilities calculate a cost estimate
int cost_segmap( MACROBLOCKD * xd,
int * segcounts,
vp8_prob * probs )
{
int cost;
int count1,count2;
// Cost the top node of the tree
count1 = segcounts[0] + segcounts[1];
count2 = segcounts[2] + segcounts[3];
cost = count1 * vp8_cost_zero(probs[0]) +
count2 * vp8_cost_one(probs[0]);
// Now add the cost of each individual segment branch
if (count1 > 0)
cost += segcounts[0] * vp8_cost_zero(probs[1]) +
segcounts[1] * vp8_cost_one(probs[1]);
if (count2 > 0)
cost += segcounts[2] * vp8_cost_zero(probs[2]) +
segcounts[3] * vp8_cost_one(probs[2]) ;
return cost;
}
void choose_segmap_coding_method( VP8_COMP *cpi )
{
VP8_COMMON *const cm = & cpi->common;
MACROBLOCKD *const xd = & cpi->mb.e_mbd;
int i;
int tot_count;
int no_pred_cost;
int t_pred_cost = INT_MAX;
int pred_context;
int mb_row, mb_col;
int segmap_index = 0;
unsigned char segment_id;
int temporal_predictor_count[SEGMENT_PREDICTION_PROBS][2];
int no_pred_segcounts[MAX_MB_SEGMENTS];
int t_unpred_seg_counts[MAX_MB_SEGMENTS];
vp8_prob no_pred_tree[MB_FEATURE_TREE_PROBS];
vp8_prob t_pred_tree[MB_FEATURE_TREE_PROBS];
vp8_prob t_nopred_prob[SEGMENT_PREDICTION_PROBS];
vpx_memset(no_pred_segcounts, 0, sizeof(no_pred_segcounts));
vpx_memset(t_unpred_seg_counts, 0, sizeof(t_unpred_seg_counts));
vpx_memset(temporal_predictor_count, 0, sizeof(temporal_predictor_count));
// First of all generate stats regarding how well the last segment map
// predicts this one
// Initialize macroblod decoder mode info context for to the first mb
// in the frame
xd->mode_info_context = cm->mi;
for (mb_row = 0; mb_row < cm->mb_rows; mb_row++)
{
for (mb_col = 0; mb_col < cm->mb_cols; mb_col++)
{
segment_id = xd->mode_info_context->mbmi.segment_id;
// Count the number of hits on each segment with no prediction
no_pred_segcounts[segment_id]++;
// Temporal prediction not allowed on key frames
if (cm->frame_type != KEY_FRAME)
{
// Get temporal prediction context
pred_context = 0;
if (mb_col != 0)
pred_context +=
(xd->mode_info_context-1)->mbmi.segment_flag;
if (mb_row != 0)
pred_context +=
(xd->mode_info_context-cm->mb_cols)->mbmi.segment_flag;
// Test to see if the last frame segment id at the same
// locationcorrectly predicts the segment_id for this MB.
// Update the prediction flag and count as appropriate;
if ( segment_id == cpi->last_segmentation_map[segmap_index] )
{
//xd->mode_info_context->mbmi.segment_predicted = 1;
xd->mode_info_context->mbmi.segment_flag = 0;
temporal_predictor_count[pred_context][0]++;
}
else
{
//xd->mode_info_context->mbmi.segment_predicted = 0;
xd->mode_info_context->mbmi.segment_flag = 1;
temporal_predictor_count[pred_context][1]++;
// Update the "undpredicted" segment count
t_unpred_seg_counts[segment_id]++;
}
}
// Step on to the next mb
xd->mode_info_context++;
// Step on to the next entry in the segment maps
segmap_index++;
}
// this is to account for the border in mode_info_context
xd->mode_info_context++;
}
// Work out probability tree for coding segments without prediction
// and the cost.
calc_segtree_probs( xd, no_pred_segcounts, no_pred_tree );
no_pred_cost = cost_segmap( xd, no_pred_segcounts, no_pred_tree );
// Key frames cannot use temporal prediction
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( xd, t_unpred_seg_counts, t_pred_tree );
t_pred_cost = cost_segmap( xd, t_unpred_seg_counts, t_pred_tree );
// Add in the cost of the signalling for each prediction context
for ( i = 0; i < SEGMENT_PREDICTION_PROBS; i++ )
{
tot_count = temporal_predictor_count[i][0] +
temporal_predictor_count[i][1];
// Work out the context probabilities for the segment
// prediction flag
if ( tot_count )
{
t_nopred_prob[i] = ( temporal_predictor_count[i][0] * 255 ) /
tot_count;
// Clamp to minimum allowed value
if ( t_nopred_prob[i] < 1 )
t_nopred_prob[i] = 1;
}
else
t_nopred_prob[i] = 1;
// Add in the predictor signaling cost
t_pred_cost += ( temporal_predictor_count[i][0] *
vp8_cost_zero(t_nopred_prob[i]) ) +
( temporal_predictor_count[i][1] *
vp8_cost_one(t_nopred_prob[i]) );
}
}
// Now choose which coding method to use.
if ( t_pred_cost < no_pred_cost )
{
xd->temporal_update = 1;
vpx_memcpy( xd->mb_segment_tree_probs,
t_pred_tree, sizeof(t_pred_tree) );
vpx_memcpy( &xd->mb_segment_pred_probs,
t_nopred_prob, sizeof(t_nopred_prob) );
}
else
{
xd->temporal_update = 0;
vpx_memcpy( xd->mb_segment_tree_probs,
no_pred_tree, sizeof(no_pred_tree) );
//vpx_memcpy( &xd->mb_segment_pred_probs,
// t_nopred_prob, sizeof(t_nopred_prob) );
}
}
#endif