/*
* Copyright (c) 2017 Gerion Entrup
*
* This file is part of FFmpeg.
*
* FFmpeg is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* FFmpeg is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License along
* with FFmpeg; if not, write to the Free Software Foundation, Inc.,
* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
*/
/**
* @file
* MPEG-7 video signature calculation and lookup filter
*/
#include "signature.h"
#define HOUGH_MAX_OFFSET 90
#define MAX_FRAMERATE 60
#define DIR_PREV 0
#define DIR_NEXT 1
#define DIR_PREV_END 2
#define DIR_NEXT_END 3
#define STATUS_NULL 0
#define STATUS_END_REACHED 1
#define STATUS_BEGIN_REACHED 2
static void fill_l1distlut(uint8_t lut[])
{
int i, j, tmp_i, tmp_j,count;
uint8_t dist;
for (i = 0, count = 0; i < 242; i++) {
for (j = i + 1; j < 243; j++, count++) {
/* ternary distance between i and j */
dist = 0;
tmp_i = i; tmp_j = j;
do {
dist += FFABS((tmp_j % 3) - (tmp_i % 3));
tmp_j /= 3;
tmp_i /= 3;
} while (tmp_i > 0 || tmp_j > 0);
lut[count] = dist;
}
}
}
static unsigned int intersection_word(const uint8_t *first, const uint8_t *second)
{
unsigned int val=0,i;
for (i = 0; i < 28; i += 4) {
val += av_popcount( (first[i] & second[i] ) << 24 |
(first[i+1] & second[i+1]) << 16 |
(first[i+2] & second[i+2]) << 8 |
(first[i+3] & second[i+3]) );
}
val += av_popcount( (first[28] & second[28]) << 16 |
(first[29] & second[29]) << 8 |
(first[30] & second[30]) );
return val;
}
static unsigned int union_word(const uint8_t *first, const uint8_t *second)
{
unsigned int val=0,i;
for (i = 0; i < 28; i += 4) {
val += av_popcount( (first[i] | second[i] ) << 24 |
(first[i+1] | second[i+1]) << 16 |
(first[i+2] | second[i+2]) << 8 |
(first[i+3] | second[i+3]) );
}
val += av_popcount( (first[28] | second[28]) << 16 |
(first[29] | second[29]) << 8 |
(first[30] | second[30]) );
return val;
}
static unsigned int get_l1dist(AVFilterContext *ctx, SignatureContext *sc, const uint8_t *first, const uint8_t *second)
{
unsigned int i;
unsigned int dist = 0;
uint8_t f, s;
for (i = 0; i < SIGELEM_SIZE/5; i++) {
if (first[i] != second[i]) {
f = first[i];
s = second[i];
if (f > s) {
/* little variation of gauss sum formula */
dist += sc->l1distlut[243*242/2 - (243-s)*(242-s)/2 + f - s - 1];
} else {
dist += sc->l1distlut[243*242/2 - (243-f)*(242-f)/2 + s - f - 1];
}
}
}
return dist;
}
/**
* calculates the jaccard distance and evaluates a pair of coarse signatures as good
* @return 0 if pair is bad, 1 otherwise
*/
static int get_jaccarddist(SignatureContext *sc, CoarseSignature *first, CoarseSignature *second)
{
int jaccarddist, i, composdist = 0, cwthcount = 0;
for (i = 0; i < 5; i++) {
if ((jaccarddist = intersection_word(first->data[i], second->data[i])) > 0) {
jaccarddist /= union_word(first->data[i], second->data[i]);
}
if (jaccarddist >= sc->thworddist) {
if (++cwthcount > 2) {
/* more than half (5/2) of distances are too wide */
return 0;
}
}
composdist += jaccarddist;
if (composdist > sc->thcomposdist) {
return 0;
}
}
return 1;
}
/**
* step through the coarsesignatures as long as a good candidate is found
* @return 0 if no candidate is found, 1 otherwise
*/
static int find_next_coarsecandidate(SignatureContext *sc, CoarseSignature *secondstart, CoarseSignature **first, CoarseSignature **second, int start)
{
/* go one coarsesignature foreword */
if (!start) {
if ((*second)->next) {
*second = (*second)->next;
} else if ((*first)->next) {
*second = secondstart;
*first = (*first)->next;
} else {
return 0;
}
}
while (1) {
if (get_jaccarddist(sc, *first, *second))
return 1;
/* next signature */
if ((*second)->next) {
*second = (*second)->next;
} else if ((*first)->next) {
*second = secondstart;
*first = (*first)->next;
} else {
return 0;
}
}
}
/**
* compares framesignatures and sorts out signatures with a l1 distance above a given threshold.
* Then tries to find out offset and differences between framerates with a hough transformation
*/
static MatchingInfo* get_matching_parameters(AVFilterContext *ctx, SignatureContext *sc, FineSignature *first, FineSignature *second)
{
FineSignature *f, *s;
size_t i, j, k, l, hmax = 0, score;
int framerate, offset, l1dist;
double m;
MatchingInfo *cands = NULL, *c = NULL;
struct {
uint8_t size;
unsigned int dist;
FineSignature *a;
uint8_t b_pos[COARSE_SIZE];
FineSignature *b[COARSE_SIZE];
} pairs[COARSE_SIZE];
typedef struct hspace_elem {
int dist;
size_t score;
FineSignature *a;
FineSignature *b;
} hspace_elem;
/* houghspace */
hspace_elem** hspace = av_malloc_array(MAX_FRAMERATE, sizeof(hspace_elem *));
/* initialize houghspace */
for (i = 0; i < MAX_FRAMERATE; i++) {
hspace[i] = av_malloc_array(2 * HOUGH_MAX_OFFSET + 1, sizeof(hspace_elem));
for (j = 0; j < HOUGH_MAX_OFFSET; j++) {
hspace[i][j].score = 0;
hspace[i][j].dist = 99999;
}
}
/* l1 distances */
for (i = 0, f = first; i < COARSE_SIZE && f->next; i++, f = f->next) {
pairs[i].size = 0;
pairs[i].dist = 99999;
pairs[i].a = f;
for (j = 0, s = second; j < COARSE_SIZE && s->next; j++, s = s->next) {
/* l1 distance of finesignature */
l1dist = get_l1dist(ctx, sc, f->framesig, s->framesig);
if (l1dist < sc->thl1) {
if (l1dist < pairs[i].dist) {
pairs[i].size = 1;
pairs[i].dist = l1dist;
pairs[i].b_pos[0] = j;
pairs[i].b[0] = s;
} else if (l1dist == pairs[i].dist) {
pairs[i].b[pairs[i].size] = s;
pairs[i].b_pos[pairs[i].size] = j;
pairs[i].size++;
}
}
}
}
/* last incomplete coarsesignature */
if (f->next == NULL) {
for (; i < COARSE_SIZE; i++) {
pairs[i].size = 0;
pairs[i].dist = 99999;
}
}
/* hough transformation */
for (i = 0; i < COARSE_SIZE; i++) {
for (j = 0; j < pairs[i].size; j++) {
for (k = i + 1; k < COARSE_SIZE; k++) {
for (l = 0; l < pairs[k].size; l++) {
if (pairs[i].b[j] != pairs[k].b[l]) {
/* linear regression */
m = (pairs[k].b_pos[l]-pairs[i].b_pos[j]) / (k-i); /* good value between 0.0 - 2.0 */
framerate = (int) m*30 + 0.5; /* round up to 0 - 60 */
if (framerate>0 && framerate <= MAX_FRAMERATE) {
offset = pairs[i].b_pos[j] - ((int) m*i + 0.5); /* only second part has to be rounded up */
if (offset > -HOUGH_MAX_OFFSET && offset < HOUGH_MAX_OFFSET) {
if (pairs[i].dist < pairs[k].dist) {
if (pairs[i].dist < hspace[framerate-1][offset+HOUGH_MAX_OFFSET].dist) {
hspace[framerate-1][offset+HOUGH_MAX_OFFSET].dist = pairs[i].dist;
hspace[framerate-1][offset+HOUGH_MAX_OFFSET].a = pairs[i].a;
hspace[framerate-1][offset+HOUGH_MAX_OFFSET].b = pairs[i].b[j];
}
} else {
if (pairs[k].dist < hspace[framerate-1][offset+HOUGH_MAX_OFFSET].dist) {
hspace[framerate-1][offset+HOUGH_MAX_OFFSET].dist = pairs[k].dist;
hspace[framerate-1][offset+HOUGH_MAX_OFFSET].a = pairs[k].a;
hspace[framerate-1][offset+HOUGH_MAX_OFFSET].b = pairs[k].b[l];
}
}
score = hspace[framerate-1][offset+HOUGH_MAX_OFFSET].score + 1;
if (score > hmax )
hmax = score;
hspace[framerate-1][offset+HOUGH_MAX_OFFSET].score = score;
}
}
}
}
}
}
}
if (hmax > 0) {
hmax = (int) (0.7*hmax);
for (i = 0; i < MAX_FRAMERATE; i++) {
for (j = 0; j < HOUGH_MAX_OFFSET; j++) {
if (hmax < hspace[i][j].score) {
if (c == NULL) {
c = av_malloc(sizeof(MatchingInfo));
if (!c)
av_log(ctx, AV_LOG_FATAL, "Could not allocate memory");
cands = c;
} else {
c->next = av_malloc(sizeof(MatchingInfo));
if (!c->next)
av_log(ctx, AV_LOG_FATAL, "Could not allocate memory");
c = c->next;
}
c->framerateratio = (i+1.0) / 30;
c->score = hspace[i][j].score;
c->offset = j-90;
c->first = hspace[i][j].a;
c->second = hspace[i][j].b;
c->next = NULL;
/* not used */
c->meandist = 0;
c->matchframes = 0;
c->whole = 0;
}
}
}
}
for (i = 0; i < MAX_FRAMERATE; i++) {
av_freep(&hspace[i]);
}
av_freep(&hspace);
return cands;
}
static int iterate_frame(double frr, FineSignature **a, FineSignature **b, int fcount, int *bcount, int dir)
{
int step;
/* between 1 and 2, because frr is between 1 and 2 */
step = ((int) 0.5 + fcount * frr) /* current frame */
-((int) 0.5 + (fcount-1) * frr);/* last frame */
if (dir == DIR_NEXT) {
if (frr >= 1.0) {
if ((*a)->next) {
*a = (*a)->next;
} else {
return DIR_NEXT_END;
}
if (step == 1) {
if ((*b)->next) {
*b = (*b)->next;
(*bcount)++;
} else {
return DIR_NEXT_END;
}
} else {
if ((*b)->next && (*b)->next->next) {
*b = (*b)->next->next;
(*bcount)++;
} else {
return DIR_NEXT_END;
}
}
} else {
if ((*b)->next) {
*b = (*b)->next;
(*bcount)++;
} else {
return DIR_NEXT_END;
}
if (step == 1) {
if ((*a)->next) {
*a = (*a)->next;
} else {
return DIR_NEXT_END;
}
} else {
if ((*a)->next && (*a)->next->next) {
*a = (*a)->next->next;
} else {
return DIR_NEXT_END;
}
}
}
return DIR_NEXT;
} else {
if (frr >= 1.0) {
if ((*a)->prev) {
*a = (*a)->prev;
} else {
return DIR_PREV_END;
}
if (step == 1) {
if ((*b)->prev) {
*b = (*b)->prev;
(*bcount)++;
} else {
return DIR_PREV_END;
}
} else {
if ((*b)->prev && (*b)->prev->prev) {
*b = (*b)->prev->prev;
(*bcount)++;
} else {
return DIR_PREV_END;
}
}
} else {
if ((*b)->prev) {
*b = (*b)->prev;
(*bcount)++;
} else {
return DIR_PREV_END;
}
if (step == 1) {
if ((*a)->prev) {
*a = (*a)->prev;
} else {
return DIR_PREV_END;
}
} else {
if ((*a)->prev && (*a)->prev->prev) {
*a = (*a)->prev->prev;
} else {
return DIR_PREV_END;
}
}
}
return DIR_PREV;
}
}
static MatchingInfo evaluate_parameters(AVFilterContext *ctx, SignatureContext *sc, MatchingInfo *infos, MatchingInfo bestmatch, int mode)
{
int dist, distsum = 0, bcount = 1, dir = DIR_NEXT;
int fcount = 0, goodfcount = 0, gooda = 0, goodb = 0;
double meandist, minmeandist = bestmatch.meandist;
int tolerancecount = 0;
FineSignature *a, *b, *aprev, *bprev;
int status = STATUS_NULL;
for (; infos != NULL; infos = infos->next) {
a = infos->first;
b = infos->second;
while (1) {
dist = get_l1dist(ctx, sc, a->framesig, b->framesig);
if (dist > sc->thl1) {
if (a->confidence >= 1 || b->confidence >= 1) {
/* bad frame (because high different information) */
tolerancecount++;
}
if (tolerancecount > 2) {
a = aprev;
b = bprev;
if (dir == DIR_NEXT) {
/* turn around */
a = infos->first;
b = infos->second;
dir = DIR_PREV;
} else {
break;
}
}
} else {
/* good frame */
distsum += dist;
goodfcount++;
tolerancecount=0;
aprev = a;
bprev = b;
if (a->confidence < 1) gooda++;
if (b->confidence < 1) goodb++;
}
fcount++;
dir = iterate_frame(infos->framerateratio, &a, &b, fcount, &bcount, dir);
if (dir == DIR_NEXT_END) {
status = STATUS_END_REACHED;
a = infos->first;
b = infos->second;
dir = iterate_frame(infos->framerateratio, &a, &b, fcount, &bcount, DIR_PREV);
}
if (dir == DIR_PREV_END) {
status |= STATUS_BEGIN_REACHED;
break;
}
if (sc->thdi != 0 && bcount >= sc->thdi) {
break; /* enough frames found */
}
}
if (bcount < sc->thdi)
continue; /* matching sequence is too short */
if ((double) goodfcount / (double) fcount < sc->thit)
continue;
if ((double) goodfcount*0.5 < FFMAX(gooda, goodb))
continue;
meandist = (double) goodfcount / (double) distsum;
if (meandist < minmeandist ||
status == STATUS_END_REACHED | STATUS_BEGIN_REACHED ||
mode == MODE_FAST){
minmeandist = meandist;
/* bestcandidate in this iteration */
bestmatch.meandist = meandist;
bestmatch.matchframes = bcount;
bestmatch.framerateratio = infos->framerateratio;
bestmatch.score = infos->score;
bestmatch.offset = infos->offset;
bestmatch.first = infos->first;
bestmatch.second = infos->second;
bestmatch.whole = 0; /* will be set to true later */
bestmatch.next = NULL;
}
/* whole sequence is automatically best match */
if (status == (STATUS_END_REACHED | STATUS_BEGIN_REACHED)) {
bestmatch.whole = 1;
break;
}
/* first matching sequence is enough, finding the best one is not necessary */
if (mode == MODE_FAST) {
break;
}
}
return bestmatch;
}
static void sll_free(MatchingInfo *sll)
{
void *tmp;
while (sll) {
tmp = sll;
sll = sll->next;
av_freep(&tmp);
}
}
static MatchingInfo lookup_signatures(AVFilterContext *ctx, SignatureContext *sc, StreamContext *first, StreamContext *second, int mode)
{
CoarseSignature *cs, *cs2;
MatchingInfo *infos;
MatchingInfo bestmatch;
MatchingInfo *i;
cs = first->coarsesiglist;
cs2 = second->coarsesiglist;
/* score of bestmatch is 0, if no match is found */
bestmatch.score = 0;
bestmatch.meandist = 99999;
bestmatch.whole = 0;
fill_l1distlut(sc->l1distlut);
/* stage 1: coarsesignature matching */
if (find_next_coarsecandidate(sc, second->coarsesiglist, &cs, &cs2, 1) == 0)
return bestmatch; /* no candidate found */
do {
av_log(ctx, AV_LOG_DEBUG, "Stage 1: got coarsesignature pair. "
"indices of first frame: %"PRIu32" and %"PRIu32"\n",
cs->first->index, cs2->first->index);
/* stage 2: l1-distance and hough-transform */
av_log(ctx, AV_LOG_DEBUG, "Stage 2: calculate matching parameters\n");
infos = get_matching_parameters(ctx, sc, cs->first, cs2->first);
if (av_log_get_level() == AV_LOG_DEBUG) {
for (i = infos; i != NULL; i = i->next) {
av_log(ctx, AV_LOG_DEBUG, "Stage 2: matching pair at %"PRIu32" and %"PRIu32", "
"ratio %f, offset %d\n", i->first->index, i->second->index,
i->framerateratio, i->offset);
}
}
/* stage 3: evaluation */
av_log(ctx, AV_LOG_DEBUG, "Stage 3: evaluate\n");
if (infos) {
bestmatch = evaluate_parameters(ctx, sc, infos, bestmatch, mode);
av_log(ctx, AV_LOG_DEBUG, "Stage 3: best matching pair at %"PRIu32" and %"PRIu32", "
"ratio %f, offset %d, score %d, %d frames matching\n",
bestmatch.first->index, bestmatch.second->index,
bestmatch.framerateratio, bestmatch.offset, bestmatch.score, bestmatch.matchframes);
sll_free(infos);
}
} while (find_next_coarsecandidate(sc, second->coarsesiglist, &cs, &cs2, 0) && !bestmatch.whole);
return bestmatch;
}