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avfilter/avf_showspectrum: properly calculate w factor

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It is used in calculating loudness of each frequency bin.

Signed-off-by: Paul B Mahol <onemda@gmail.com>
This commit is contained in:
Paul B Mahol 2015-12-28 23:45:34 +01:00
parent e30e5c83ae
commit efa666e0da
1 changed files with 7 additions and 1 deletions
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8
libavfilter/avf_showspectrum.c
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@ -60,6 +60,7 @@ typedef struct {
FFTSample **rdft_data; ///< bins holder for each (displayed) channels
float *window_func_lut; ///< Window function LUT
int win_func;
double win_scale;
float overlap;
float *combine_buffer; ///< color combining buffer (3 * h items)
} ShowSpectrumContext;
@ -231,6 +232,11 @@ static int config_output(AVFilterLink *outlink)
return AVERROR(ENOMEM);
ff_generate_window_func(s->window_func_lut, win_size, s->win_func, &s->overlap);
for (s->win_scale = 0, i = 0; i < win_size; i++) {
s->win_scale += s->window_func_lut[i] * s->window_func_lut[i];
}
s->win_scale = 1. / (sqrt(s->win_scale) * 32768.);
/* prepare the initial picref buffer (black frame) */
av_frame_free(&s->outpicref);
s->outpicref = outpicref =
@ -315,7 +321,7 @@ static int plot_spectrum_column(AVFilterLink *inlink, AVFrame *insamples)
* height (or half the RDFT window size) */
const int nb_freq = 1 << (s->rdft_bits - 1);
const int win_size = nb_freq << 1;
const double w = 1. / (sqrt(nb_freq) * 32768.);
const double w = s->win_scale;
int h = s->orientation == VERTICAL ? s->channel_height : s->channel_width;
int ch, plane, n, x, y;