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SHERLOCK: Better decoding of ADPCM 4bit sounds, courtesy of m_kiewitz

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Strangerke 2015-05-17 14:33:57 +02:00
parent e909f1325f
commit 239562fc01
2 changed files with 46 additions and 27 deletions
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70
engines/sherlock/sound.cpp
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@ -63,29 +63,44 @@ void Sound::loadSound(const Common::String &name, int priority) {
// No implementation required in ScummVM
}
char Sound::decodeSample(char sample, byte& prediction, int& step) {
char diff = ((sample & 0x07) << step);
static int8 creativeADPCM_ScaleMap[64] = {
0, 1, 2, 3, 4, 5, 6, 7, 0, -1, -2, -3, -4, -5, -6, -7,
1, 3, 5, 7, 9, 11, 13, 15, -1, -3, -5, -7, -9, -11, -13, -15,
2, 6, 10, 14, 18, 22, 26, 30, -2, -6, -10, -14, -18, -22, -26, -30,
4, 12, 20, 28, 36, 44, 52, 60, -4, -12, -20, -28, -36, -44, -52, -60
};
if (sample & 0x08) {
if (prediction > diff)
prediction = prediction - ((sample & 0x07) << step);
else
prediction = 0;
static uint8 creativeADPCM_AdjustMap[64] = {
0, 0, 0, 0, 0, 16, 16, 16,
0, 0, 0, 0, 0, 16, 16, 16,
240, 0, 0, 0, 0, 16, 16, 16,
240, 0, 0, 0, 0, 16, 16, 16,
240, 0, 0, 0, 0, 16, 16, 16,
240, 0, 0, 0, 0, 16, 16, 16,
240, 0, 0, 0, 0, 0, 0, 0,
240, 0, 0, 0, 0, 0, 0, 0
};
byte Sound::decodeSample(byte sample, byte& reference, int16& scale) {
int16 samp = sample + scale;
int16 ref = 0;
// clip bad ADPCM-4 sample
CLIP(samp, 0, 63);
ref = reference + creativeADPCM_ScaleMap[samp];
if (ref > 0xff) {
reference = 0xff;
} else {
if (prediction < 0xff - diff)
prediction = prediction + ((sample&0x07) << step);
else
prediction = 0xff;
if (ref < 0x00) {
reference = 0;
} else {
reference = (uint8)(ref & 0xff);
}
}
if ((sample & 0x07) >= 5 && step < 3) {
step ++;
} else if ((sample & 0x07) == 0 && step > 0) {
step --;
}
return prediction;
scale = (scale + creativeADPCM_AdjustMap[samp]) & 0xff;
return reference;
}
bool Sound::playSound(const Common::String &name, WaitType waitType, int priority) {
@ -94,7 +109,7 @@ bool Sound::playSound(const Common::String &name, WaitType waitType, int priorit
Common::String filename = name;
if (!filename.contains('.'))
filename += ".SND";
Common::SeekableReadStream *stream = _vm->_res->load(filename);
if (!stream)
@ -107,16 +122,18 @@ bool Sound::playSound(const Common::String &name, WaitType waitType, int priorit
byte *ptr = data;
stream->read(ptr, size);
assert(size > 2);
byte *decoded = (byte *)malloc((size - 1) * 2);
// +127 to eliminate the pop when the sound starts (signed vs unsigned PCM). Still does not help with the pop at the end
byte prediction = (ptr[0] & 0x0f) + 127;
int step = 0;
// Holmes uses Creative ADPCM 4-bit data
int counter = 0;
byte reference = ptr[0];
int16 scale = 0;
for(int i = 1; i < size; i++) {
decoded[counter++] = decodeSample((ptr[i]>>4)&0x0f, prediction, step);
decoded[counter++] = decodeSample((ptr[i]>>0)&0x0f, prediction, step);
decoded[counter++] = decodeSample((ptr[i]>>4)&0x0f, reference, scale);
decoded[counter++] = decodeSample((ptr[i]>>0)&0x0f, reference, scale);
}
free(data);
@ -149,7 +166,7 @@ bool Sound::playSound(const Common::String &name, WaitType waitType, int priorit
break;
}
} while (!_vm->shouldQuit() && _mixer->isSoundHandleActive(_effectsHandle));
_soundPlaying = false;
_mixer->stopHandle(_effectsHandle);
@ -234,3 +251,4 @@ void Sound::freeDigiSound() {
}
} // End of namespace Sherlock