mirror/RetroArch
1
0
Fork 0
mirror of https://github.com/libretro/RetroArch synced 2025-01-30 21:32:45 +00:00
Code Issues Packages Projects Releases Wiki Activity

Create a correct linear phase filter.

Browse Source
This commit is contained in:
Themaister 2014-05-29 03:11:30 +02:00
parent 01e0fac94f
commit 87810fe9c6
1 changed files with 7 additions and 5 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

12
audio/filters/eq.c
View File

@ -224,7 +224,7 @@ static void create_filter(struct eq_data *eq, unsigned size_log2,
double window_mod = 1.0 / kaiser_window(0.0, beta);
fft_t *fft = fft_new(size_log2);
float *time_filter = (float*)calloc(eq->block_size * 2, sizeof(*time_filter));
float *time_filter = (float*)calloc(eq->block_size * 2 + 1, sizeof(*time_filter));
if (!fft || !time_filter)
goto end;
@ -251,7 +251,7 @@ static void create_filter(struct eq_data *eq, unsigned size_log2,
for (i = 0; i < (int)eq->block_size; i++)
{
// Kaiser window.
double phase = (double)i / (eq->block_size - 1);
double phase = (double)i / eq->block_size;
phase = 2.0 * (phase - 0.5);
time_filter[i] *= window_mod * kaiser_window(phase, beta);
}
@ -261,14 +261,16 @@ static void create_filter(struct eq_data *eq, unsigned size_log2,
FILE *file = fopen("/tmp/test.txt", "w");
if (file)
{
for (i = 0; i < (int)eq->block_size; i++)
fprintf(file, "%.6f\n", time_filter[i]);
for (i = 0; i < (int)eq->block_size - 1; i++)
fprintf(file, "%.6f\n", time_filter[i + 1]);
fclose(file);
}
#endif
// Padded FFT to create our FFT filter.
fft_process_forward(eq->fft, eq->filter, time_filter, 1);
// Make our even-length filter odd by discarding the first coefficient.
// For some interesting reason, this allows us to design an odd-length linear phase filter.
fft_process_forward(eq->fft, eq->filter, time_filter + 1, 1);
end:
fft_free(fft);