cpal/src/conversions.rs

71 lines
1.9 KiB
Rust

/*!
This module contains function that will convert from one PCM format to another.
This includes conversion between samples formats, channels or sample rates.
*/
pub fn convert_samples_rate<T>(input: &[T], from: ::SamplesRate, to: ::SamplesRate) -> Vec<T>
where T: Copy
{
let from = from.0;
let to = to.0;
// if `from` is a multiple of `to` (for example `from` is 44100 and `to` is 22050),
// then we simply skip some samples
if from % to == 0 {
let mut result = Vec::new();
for element in input.chunks((from / to) as uint) {
result.push(element[0]);
}
return result;
}
// if `to` is a multiple of `from` (for example `to` is 44100 and `from` is 22050)
// TODO: dumb algorithm
// FIXME: doesn't take channels into account
if to % from == 0 {
let mut result = Vec::new();
for element in input.windows(2) {
for _ in range(0, (to / from) as uint) {
result.push(element[0]);
}
}
for _ in range(0, (to / from) as uint) {
result.push(*input.last().unwrap());
}
return result;
}
unimplemented!()
}
pub fn convert_channels<T>(input: &[T], from: ::ChannelsCount, to: ::ChannelsCount) -> Vec<T>
where T: Copy
{
assert!(input.len() % from as uint == 0);
let mut result = Vec::new();
for element in input.chunks(from as uint) {
// copying the common channels
for i in range(0, ::std::cmp::min(from, to)) {
result.push(element[i as uint]);
}
// adding extra ones
for i in range(0, ::std::cmp::max(0, to - from)) {
result.push(element[i as uint % element.len()]);
}
}
result
}
/*#[cfg(test)]
mod test {
#[test]
fn test_convert_channels() {
}
}*/