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audio/pcmconv: implement stereo -> mono conversion (mixing)

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This commit is contained in:
cinap_lenrek 2012-12-14 17:16:50 +01:00
parent 776f3726dd
commit 1fdd311f2f
1 changed files with 39 additions and 16 deletions
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55
sys/src/cmd/audio/pcmconv/pcmconv.c
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@ -41,6 +41,19 @@ enum {
One = 1<<Np,
};
#define MAXINT ((int)(~0UL>>1))
#define MININT (MAXINT+1)
int
clip(vlong v)
{
if(v > MAXINT)
return MAXINT;
if(v < MININT)
return MININT;
return v;
}
int
chaninit(Chan *c, int irate, int orate, int count)
{
@ -132,13 +145,7 @@ filter(Chan *c)
v *= c->u;
v >>= 27;
/* clipping */
if(v > 0x7fffffffLL)
return 0x7fffffff;
if(v < -0x80000000LL)
return -0x80000000;
return v;
return clip(v);
}
int*
@ -211,6 +218,15 @@ dither(int *y, int ibits, int obits, int count)
}
}
void
mixin(int *y, int *x, int count)
{
while(count--){
*y = clip((vlong)*y + *x++);
y++;
}
}
void
siconv(int *dst, uchar *src, int bits, int skip, int count)
{
@ -322,11 +338,11 @@ ficonv(int *dst, uchar *src, int bits, int skip, int count)
f = *((float*)src), src += skip;
if(f > 1.0)
*dst++ = 0x7fffffff;
*dst++ = MAXINT;
else if(f < -1.0)
*dst++ = -0x80000000;
*dst++ = MININT;
else
*dst++ = f*2147483647.f;
*dst++ = f*((float)MAXINT);
}
} else {
while(count--){
@ -334,11 +350,11 @@ ficonv(int *dst, uchar *src, int bits, int skip, int count)
d = *((double*)src), src += skip;
if(d > 1.0)
*dst++ = 0x7fffffff;
*dst++ = MAXINT;
else if(d < -1.0)
*dst++ = -0x80000000;
*dst++ = MININT;
else
*dst++ = d*2147483647.f;
*dst++ = d*((float)MAXINT);
}
}
}
@ -489,12 +505,12 @@ foconv(int *src, uchar *dst, int bits, int skip, int count)
{
if(bits == 32){
while(count--){
*((float*)dst) = *src++ / 2147483647.f;
*((float*)dst) = *src++ / ((float)MAXINT);
dst += skip;
}
} else {
while(count--){
*((double*)dst) = *src++ / 2147483647.f;
*((double*)dst) = *src++ / ((double)MAXINT);
dst += skip;
}
}
@ -662,7 +678,8 @@ main(int argc, char *argv[])
for(k=0; k < i.channels; k++)
nout = chaninit(&ch[k], i.rate, o.rate, nin);
out = sbrk(sizeof(int) * nout);
/* out is also used for mixing before resampling, so needs to be max(nin, nout) */
out = sbrk(sizeof(int) * (nout>nin? nout: nin));
obuf = sbrk(o.framesz * nout);
for(;;){
@ -676,6 +693,12 @@ main(int argc, char *argv[])
l -= n;
n /= i.framesz;
(*iconv)(in, ibuf, i.bits, i.framesz, n);
if(i.channels > o.channels){
for(k=1; k<i.channels; k++){
(*iconv)(out, ibuf + k*((i.bits+7)/8), i.bits, i.framesz, n);
mixin(in, out, n);
}
}
dither(in, i.abits, o.abits, n);
m = resample(&ch[0], in, out, n) - out;
if(m < 1){