From efa666e0da5e5fd2ded2e7dce4191bf04ac35952 Mon Sep 17 00:00:00 2001 From: Paul B Mahol Date: Mon, 28 Dec 2015 23:45:34 +0100 Subject: avfilter/avf_showspectrum: properly calculate w factor It is used in calculating loudness of each frequency bin. Signed-off-by: Paul B Mahol --- libavfilter/avf_showspectrum.c | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-) (limited to 'libavfilter/avf_showspectrum.c') diff --git a/libavfilter/avf_showspectrum.c b/libavfilter/avf_showspectrum.c index fa994574a6..187213575d 100644 --- a/libavfilter/avf_showspectrum.c +++ b/libavfilter/avf_showspectrum.c @@ -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; -- cgit v1.2.3