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a slight quality improvement to the slow-motion handling part of the N audio synchronizer method (for an example, mario's jump sounded all crackly before)

This commit is contained in:
nitsuja 2009-11-08 06:22:52 +00:00
parent 19e82b56f8
commit 09c69e5a2c
1 changed files with 55 additions and 5 deletions
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60
desmume/src/metaspu/metaspu.cpp
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@ -265,9 +265,9 @@ public:
int audiosize = samples_requested;
int queued = sampleQueue.size();
// truncate input and output sizes to multiples of 8 because I am too lazy to deal with odd numbers
audiosize &= ~7;
queued &= ~7;
// I am too lazy to deal with odd numbers
audiosize &= ~1;
queued &= ~1;
if(queued > 0x200 && audiosize > 0) // is there any work to do?
{
@ -313,8 +313,50 @@ public:
// yes, this means we are spending some stretches of time playing the sound backwards,
// but the stretches are short enough that this doesn't sound weird.
// this lets us avoid most crackling problems due to the endpoints matching up.
// TODO: it might help to calculate the approximate fundamental frequency
// and reduce either buffer size such that the reflections line up with it.
// first calculate a shorter-than-full window
// that has minimal slope at the endpoints
// (to further reduce crackling, especially in sine waves)
int beststart = 0, extraAtEnd = 0;
{
int bestend = queued;
static const int worstdiff = 99999999;
int beststartdiff = worstdiff;
int bestenddiff = worstdiff;
for(int i = 0; i < 128; i+=2)
{
int diff = abs(sampleQueue[i].l - sampleQueue[i+1].l) + abs(sampleQueue[i].r - sampleQueue[i+1].r);
if(diff < beststartdiff)
{
beststartdiff = diff;
beststart = i;
}
}
for(int i = queued-3; i > queued-3-128; i-=2)
{
int diff = abs(sampleQueue[i].l - sampleQueue[i+1].l) + abs(sampleQueue[i].r - sampleQueue[i+1].r);
if(diff < bestenddiff)
{
bestenddiff = diff;
bestend = i+1;
}
}
extraAtEnd = queued - bestend;
queued = bestend - beststart;
int oksize = queued;
while(oksize + queued*2 + beststart + extraAtEnd <= samples_requested)
oksize += queued*2;
audiosize = oksize;
for(int x = 0; x < beststart; x++)
{
emit_sample(buf,sampleQueue[x]);
}
sampleQueue.erase(sampleQueue.begin(), sampleQueue.begin() + beststart);
}
int midpointX = audiosize >> 1;
int midpointY = queued >> 1;
@ -372,6 +414,14 @@ public:
int i = (queued-1) - pingpong((int)audiosize-1 - x + queued*2, queued);
emit_sample(buf,sampleQueue[i]);
}
for(int x = 0; x < extraAtEnd; x++)
{
int i = queued + x;
emit_sample(buf,sampleQueue[i]);
}
queued += extraAtEnd;
audiosize += beststart + extraAtEnd;
} //end else
sampleQueue.erase(sampleQueue.begin(), sampleQueue.begin() + queued);