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avcodec/kbdwin: Remove low precision intermediate in ff_kbd_window_init_fixed() 

Previously floats where scaled up to 32bit int, but floats do not
have 32bits in their mantisse so a quarter of the bits where nonsense.

It seems no fate test is affected by this change, which is interresting

Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
This commit is contained in:
Michael Niedermayer 2023-05-23 01:19:32 +02:00
parent 17ecb224e9
commit 988fd5743d
No known key found for this signature in database
GPG Key ID: B18E8928B3948D64
1 changed files with 11 additions and 9 deletions
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20
libavcodec/kbdwin.c
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@ -21,7 +21,7 @@
#include "libavutil/attributes.h"
#include "kbdwin.h"
av_cold void ff_kbd_window_init(float *window, float alpha, int n)
av_cold static void kbd_window_init(float *float_window, int *int_window, float alpha, int n)
{
int i;
double sum = 0.0, tmp;
@ -40,20 +40,22 @@ av_cold void ff_kbd_window_init(float *window, float alpha, int n)
for (i = 0; i <= n / 2; i++) {
sum += temp[i];
window[i] = sqrt(sum * scale);
if (float_window) float_window[i] = sqrt(sum * scale);
else int_window[i] = lrint(2147483647 * sqrt(sum * scale));
}
for (; i < n; i++) {
sum += temp[n - i];
window[i] = sqrt(sum * scale);
if (float_window) float_window[i] = sqrt(sum * scale);
else int_window[i] = lrint(2147483647 * sqrt(sum * scale));
}
}
av_cold void ff_kbd_window_init(float *window, float alpha, int n)
{
kbd_window_init(window, NULL, alpha, n);
}
av_cold void ff_kbd_window_init_fixed(int32_t *window, float alpha, int n)
{
int i;
float local_window[FF_KBD_WINDOW_MAX];
ff_kbd_window_init(local_window, alpha, n);
for (i = 0; i < n; i++)
window[i] = (int)floor(2147483647.0 * local_window[i] + 0.5);
kbd_window_init(NULL, window, alpha, n);
}