On Wed, Mar 1, 2017 at 9:24 PM, Muhammad Faiz <[email protected]> wrote:
> this gives better frequency response
>
> Signed-off-by: Muhammad Faiz <[email protected]>
> ---
> libswresample/resample.c | 14 +++++++-------
> 1 file changed, 7 insertions(+), 7 deletions(-)
>
Test case, from 44100 to 705600 (16*44100)
ffmpeg -filter_complex "aevalsrc='if(n-300,0,1)',
aresample=osr=705600:filter_size=16" -f f32le - | ./freq-resp >
freq-resp.txt
#include <stdio.h>
#include <math.h>
#include <libavcodec/avfft.h>
#define BITS 16
#define OSR 705600
#define ISR 44100
#define LENGTH (1 << BITS)
int main(int argc, char **argv)
{
static FFTComplex buf[LENGTH];
int k;
FFTContext *fft = av_fft_init(BITS, 0);
for (k = 0; k < LENGTH; k++)
fread(buf+k, sizeof(float), 1, stdin);
av_fft_permute(fft, buf);
av_fft_calc(fft, buf);
for (k = 0; k <= LENGTH/2; k++)
printf("%.17f %.17f\n", (double) k * OSR / LENGTH, 20.0 * log10(hypot(buf[k].re, buf[k].im) * ISR / OSR));
return 0;
}
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