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avfilter/palettegen: move box stats computation to a dedicated function

This commit is contained in:
Clément Bœsch 2022-12-27 13:58:07 +01:00
parent a0587c0219
commit 21f7814238
1 changed files with 38 additions and 26 deletions
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64
libavfilter/vf_palettegen.c
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@ -40,6 +40,8 @@ struct color_ref {
/* Store a range of colors */
struct range_box {
uint32_t color; // average color
int major_axis; // best axis candidate for cutting the box
uint64_t weight; // sum of all the weights of the colors
int64_t variance; // overall variance of the box (how much the colors are spread)
int start; // index in PaletteGenContext->refs
int len; // number of referenced colors
@ -143,6 +145,35 @@ static av_always_inline int diff(const uint32_t a, const uint32_t b)
return dr*dr + dg*dg + db*db;
}
static void compute_box_stats(PaletteGenContext *s, struct range_box *box)
{
int rr, gr, br;
/* compute the box weight (sum all the weights of the colors in the
* range) and its boundings */
uint8_t min[3] = {0xff, 0xff, 0xff};
uint8_t max[3] = {0x00, 0x00, 0x00};
box->weight = 0;
for (int i = box->start; i < box->start + box->len; i++) {
const struct color_ref *ref = s->refs[i];
const uint32_t rgb = ref->color;
const uint8_t r = rgb >> 16 & 0xff, g = rgb >> 8 & 0xff, b = rgb & 0xff;
min[0] = FFMIN(r, min[0]), max[0] = FFMAX(r, max[0]);
min[1] = FFMIN(g, min[1]), max[1] = FFMAX(g, max[1]);
min[2] = FFMIN(b, min[2]), max[2] = FFMAX(b, max[2]);
box->weight += ref->count;
}
/* define the axis to sort by according to the widest range of colors */
rr = max[0] - min[0];
gr = max[1] - min[1];
br = max[2] - min[2];
box->major_axis = 1; // pick green by default (the color the eye is the most sensitive to)
if (br >= rr && br >= gr) box->major_axis = 2;
if (rr >= gr && rr >= br) box->major_axis = 0;
if (gr >= rr && gr >= br) box->major_axis = 1; // prefer green again
}
/**
* Find the next box to split: pick the one with the highest variance
*/
@ -324,35 +355,16 @@ static AVFrame *get_palette_frame(AVFilterContext *ctx)
s->nb_boxes = 1;
while (box && box->len > 1) {
int i, rr, gr, br, longest;
uint64_t median, box_weight = 0;
int i, longest;
uint64_t median, box_weight;
/* compute the box weight (sum all the weights of the colors in the
* range) and its boundings */
uint8_t min[3] = {0xff, 0xff, 0xff};
uint8_t max[3] = {0x00, 0x00, 0x00};
for (i = box->start; i < box->start + box->len; i++) {
const struct color_ref *ref = s->refs[i];
const uint32_t rgb = ref->color;
const uint8_t r = rgb >> 16 & 0xff, g = rgb >> 8 & 0xff, b = rgb & 0xff;
min[0] = FFMIN(r, min[0]), max[0] = FFMAX(r, max[0]);
min[1] = FFMIN(g, min[1]), max[1] = FFMAX(g, max[1]);
min[2] = FFMIN(b, min[2]), max[2] = FFMAX(b, max[2]);
box_weight += ref->count;
}
compute_box_stats(s, box);
longest = box->major_axis;
box_weight = box->weight;
/* define the axis to sort by according to the widest range of colors */
rr = max[0] - min[0];
gr = max[1] - min[1];
br = max[2] - min[2];
longest = 1; // pick green by default (the color the eye is the most sensitive to)
if (br >= rr && br >= gr) longest = 2;
if (rr >= gr && rr >= br) longest = 0;
if (gr >= rr && gr >= br) longest = 1; // prefer green again
ff_dlog(ctx, "box #%02X [%6d..%-6d] (%6d) w:%-6"PRIu64" ranges:[%2x %2x %2x] sort by %c (already sorted:%c) ",
ff_dlog(ctx, "box #%02X [%6d..%-6d] (%6d) w:%-6"PRIu64" sort by %c (already sorted:%c) ",
box_id, box->start, box->start + box->len - 1, box->len, box_weight,
rr, gr, br, "rgb"[longest], box->sorted_by == longest ? 'y':'n');
"rgb"[longest], box->sorted_by == longest ? 'y':'n');
/* sort the range by its longest axis if it's not already sorted */
if (box->sorted_by != longest) {