From d39fae08866efebbfdf25951fbaff4df9d26e6b3 Mon Sep 17 00:00:00 2001
From: Paul B Mahol <onemda@gmail.com>
Date: Fri, 5 Oct 2018 00:15:26 +0200
Subject: [PATCH] avfilter/avf_showspectrum: fix scaling in zoom mode
---
libavfilter/avf_showspectrum.c | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)
diff --git a/libavfilter/avf_showspectrum.c b/libavfilter/avf_showspectrum.c
index 38d0a9d7680..a750b9a3f1f 100644
--- a/libavfilter/avf_showspectrum.c
+++ b/libavfilter/avf_showspectrum.c
@@ -340,12 +340,12 @@ static int run_channel_fft(AVFilterContext *ctx, void *arg, int jobnr, int nb_jo
FFTComplex *h = s->fft_scratch[ch];
int L = s->buf_size;
int N = s->win_size;
- int M = s->win_size;
+ int M = s->win_size / 2;
- phi = 2.0 * M_PI * (s->stop - s->start) / (double)inlink->sample_rate / (s->win_size - 1);
+ phi = 2.0 * M_PI * (s->stop - s->start) / (double)inlink->sample_rate / (M - 1);
theta = 2.0 * M_PI * s->start / (double)inlink->sample_rate;
- for (int n = 0; n < s->win_size; n++) {
+ for (int n = 0; n < M; n++) {
h[n].re = cos(n * n / 2.0 * phi);
h[n].im = sin(n * n / 2.0 * phi);
}
--
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