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lavfi/histogram: cache log2 of max_hval 

Instead of calculating same value over and over again.

Signed-off-by: Paul B Mahol <onemda@gmail.com>
This commit is contained in:
Paul B Mahol 2013-05-19 14:30:42 +00:00
parent b154d203b1
commit 68c4633fa8
1 changed files with 6 additions and 5 deletions
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11
libavfilter/vf_histogram.c
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@ -39,7 +39,6 @@ typedef struct HistogramContext {
const AVClass *class; ///< AVClass context for log and options purpose
enum HistogramMode mode;
unsigned histogram[256];
unsigned max_hval;
int ncomp;
const uint8_t *bg_color;
const uint8_t *fg_color;
@ -191,6 +190,8 @@ static int filter_frame(AVFilterLink *inlink, AVFrame *in)
case MODE_LEVELS:
for (k = 0; k < h->ncomp; k++) {
int start = k * (h->level_height + h->scale_height) * h->display_mode;
double max_hval_log;
unsigned max_hval = 0;
for (i = 0; i < in->height; i++) {
src = in->data[k] + i * in->linesize[k];
@ -199,15 +200,16 @@ static int filter_frame(AVFilterLink *inlink, AVFrame *in)
}
for (i = 0; i < 256; i++)
h->max_hval = FFMAX(h->max_hval, h->histogram[i]);
max_hval = FFMAX(max_hval, h->histogram[i]);
max_hval_log = log2(max_hval + 1);
for (i = 0; i < outlink->w; i++) {
int col_height;
if (h->levels_mode)
col_height = round(h->level_height * (1. - (log2(h->histogram[i] + 1) / log2(h->max_hval + 1))));
col_height = round(h->level_height * (1. - (log2(h->histogram[i] + 1) / max_hval_log)));
else
col_height = h->level_height - (h->histogram[i] * (int64_t)h->level_height + h->max_hval - 1) / h->max_hval;
col_height = h->level_height - (h->histogram[i] * (int64_t)h->level_height + max_hval - 1) / max_hval;
for (j = h->level_height - 1; j >= col_height; j--) {
if (h->display_mode) {
@ -222,7 +224,6 @@ static int filter_frame(AVFilterLink *inlink, AVFrame *in)
}
memset(h->histogram, 0, 256 * sizeof(unsigned));
h->max_hval = 0;
}
break;
case MODE_WAVEFORM: