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| author | Simon Howard | 2010-08-07 16:07:00 +0000 |
|---|---|---|
| committer | Simon Howard | 2010-08-07 16:07:00 +0000 |
| commit | 5e9a9a52dbebabda79f221caf318dd8fba4b0781 (patch) | |
| tree | fece713f1731ebdc2e66b19ba4554c7baf8220a1 /src/i_sdlsound.c | |
| parent | 05cafe91729446ebd28f3fdab2302277c53530d1 (diff) | |
| download | chocolate-doom-5e9a9a52dbebabda79f221caf318dd8fba4b0781.tar.gz chocolate-doom-5e9a9a52dbebabda79f221caf318dd8fba4b0781.tar.bz2 chocolate-doom-5e9a9a52dbebabda79f221caf318dd8fba4b0781.zip | |
Fix sound resampling low pass filter.
Subversion-branch: /trunk/chocolate-doom
Subversion-revision: 1951
Diffstat (limited to 'src/i_sdlsound.c')
| -rw-r--r-- | src/i_sdlsound.c | 9 |
1 files changed, 6 insertions, 3 deletions
diff --git a/src/i_sdlsound.c b/src/i_sdlsound.c index d51345c7..ff191202 100644 --- a/src/i_sdlsound.c +++ b/src/i_sdlsound.c @@ -244,12 +244,15 @@ static void ExpandSoundData_SDL(byte *data, // (maximum frequency, by nyquist) dt = 1.0f / mixer_freq; - rc = 1.0f / (3.14f * samplerate); + rc = 1.0f / (2 * 3.14f * samplerate); alpha = dt / (rc + dt); - for (i=1; i<expanded_length; ++i) + // Both channels are processed in parallel, hence [i-2]: + + for (i=2; i<expanded_length * 2; ++i) { - expanded[i] = (Sint16) (alpha * expanded[i] + (1 - alpha) * expanded[i-1]); + expanded[i] = (Sint16) (alpha * expanded[i] + + (1 - alpha) * expanded[i-2]); } } #endif /* #ifdef LOW_PASS_FILTER */ |