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add 11025/22050 to 44100 interpolation for PCM samples

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XProger
2018-02-12 04:28:27 +03:00
parent 7b61ceb638
commit a423260f02
1 changed files with 47 additions and 10 deletions
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57
src/sound.h
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@@ -150,33 +150,70 @@ namespace Sound {
struct PCM : Decoder {
int freq, size, bits;
Frame frameLast;
PCM(Stream *stream, int channels, int freq, int size, int bits) : Decoder(stream, channels), freq(freq), size(size), bits(bits) {}
PCM(Stream *stream, int channels, int freq, int size, int bits) : Decoder(stream, channels), freq(freq), size(size), bits(bits) { frameLast.L = frameLast.R = 0; }
virtual int decode(Frame *frames, int count) {
if (stream->pos - offset >= size) return 0;
// ! in the original game series only 11025 and 22050 Hz single channel samples were used ! //
Frame frame;
if (bits == 16) {
int16 value;
if (channels == 2) {
frames[0].L = stream->read(value);
frames[0].R = stream->read(value);
frame.L = stream->read(value);
frame.R = stream->read(value);
} else
frames[0].L = frames[0].R = stream->read(value);
frame.L = frame.R = stream->read(value);
} else if (bits == 8) {
uint8 value;
if (channels == 2) {
frames[0].L = stream->read(value) * 257 - 32768;
frames[0].R = stream->read(value) * 257 - 32768;
frame.L = stream->read(value) * 257 - 32768;
frame.R = stream->read(value) * 257 - 32768;
} else
frames[0].L = frames[0].R = stream->read(value) * 257 - 32768;
frame.L = frame.R = stream->read(value) * 257 - 32768;
} else {
ASSERT(false);
return 0;
}
int k = 44100 / freq;
for (int i = 1; i < k; i++) frames[i] = frames[0]; // TODO: lerp
return k;
int dL = int(frame.L) - int(frameLast.L);
int dR = int(frame.R) - int(frameLast.R);
switch (freq) {
case 11025 :
if (channels == 2) {
frames[0].L = frameLast.L + dL / 4; // 0.25 L
frames[0].R = frameLast.R + dR / 4; // 0.25 R
frames[1].L = frameLast.L + dL / 2; // 0.50 L
frames[1].R = frameLast.R + dR / 2; // 0.50 R
frames[2].L = frameLast.L + dL * 3 / 4; // 0.75 L
frames[2].R = frameLast.R + dR * 3 / 4; // 0.75 R
} else {
frames[0].L = frames[0].R = frameLast.L + dL / 4; // 0.25 LR
frames[1].L = frames[1].R = frameLast.L + dL / 2; // 0.50 LR
frames[2].L = frames[2].R = frameLast.L + dL * 3 / 4; // 0.75 LR
}
frames[3] = frameLast = frame; // 1.00 LR
return 4;
case 22050 :
if (channels == 2) {
frames[0].L = frameLast.L + dL / 2; // 0.50 L
frames[0].R = frameLast.R + dR / 2; // 0.50 R
} else
frames[0].L = frames[0].R = frameLast.L + dL / 2; // 0.50 LR
frames[1] = frameLast = frame; // 1.00 LR
return 2;
case 44100 : // not used
frames[0] = frameLast = frame;
return 1;
default : // impossible
ASSERT(false);
int k = 44100 / freq;
for (int i = 0; i < k; i++) frames[i] = frame; // no lerp
return k;
}
}
};