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Merge pull request #2107 from Dandandan/optimizemixer

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Optimize Mixer::EffectPanS16
This commit is contained in:
Ted John
2015-10-23 13:28:40 +01:00
parent 2e64527771 fdbd08e306
commit a24b3e114c
1 changed files with 10 additions and 3 deletions
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13
src/audio/mixer.cpp
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@@ -738,10 +738,17 @@ void Mixer::MixChannel(Channel& channel, uint8* data, int length)
void Mixer::EffectPanS16(Channel& channel, sint16* data, int length)
{
const float dt = 1.0f / (length * 2);
float left_volume = channel.oldvolume_l;
float right_volume = channel.oldvolume_r;
const float d_left = dt * (channel.volume_l - channel.oldvolume_l);
const float d_right = dt * (channel.volume_r - channel.oldvolume_r);
for (int i = 0; i < length * 2; i += 2) {
float t = (float)i / (length * 2);
data[i] = (sint16)(data[i] * ((1.0 - t) * channel.oldvolume_l + t * channel.volume_l));
data[i + 1] = (sint16)(data[i + 1] * ((1.0 - t) * channel.oldvolume_r + t * channel.volume_r));
data[i] = (sint16)(data[i] * left_volume);
data[i + 1] = (sint16)(data[i + 1] * right_volume);
left_volume += d_left;
right_volume += d_right;
}
}