//decimate sound to SAMPLE_RATE, using averaging
void decimate(const u::bytes& s, u::bytes& d, size_t channels, size_t skip)
{
REQUIRE_FALSE(s.empty());
REQUIRE_EQUAL(s.size() % 2, 0);
//get sizes
auto dz = (s.size() / skip);
auto nz = d.size() + dz;
//add padding
if(nz % 2 == 1) nz += 1;
CHECK_EQUAL(nz % 2, 0);
//resize dest
const auto odz = d.size();
d.resize(nz);
//cast to short arrays
auto ss = reinterpret_cast<const short*>(s.data());
const auto sz = s.size() / 2;
auto sd = reinterpret_cast<short*>(d.data());
const auto sdz = nz / 2;
int accum = 0;
size_t c = 1;
size_t si = 0;
auto di = odz / 2;
for(;si < sz; si+=channels)
{
accum += static_cast<int>(ss[si]);
if(c == skip)
{
accum /= c;
sd[di] = accum;
di++;
accum = 0;
c = 1;
continue;
}
c++;
}
//repeat last value if we have padding
si = sz-1;
while(di < sdz)
{
sd[di] = ss[si];
di++;
}
CHECK_EQUAL(di, sdz);
}
void inflate(const u::bytes& s, u::bytes& d, size_t channels, size_t rep)
{
REQUIRE_EQUAL(s.size() % 2, 0);
rep*=channels;
d.resize(s.size() * rep);
auto ss = reinterpret_cast<const short*>(s.data());
auto sz = s.size() / 2;
auto sd = reinterpret_cast<short*>(d.data());
size_t di = 0;
for(size_t si = 0; si < sz; si++)
for(size_t p = 0; p < rep; p++, di++)
sd[di] = ss[si];
}