# Rust: `no_std` digital low pass filter library
This is a `no_std` Rust library for simple digital low pass filters. You can use it for example to
get the low frequencies from a song.
**I'm not an expert on digital signal processing. Code contributions are highly welcome! :)**
## How to use
```rust
use audio_visualizer::waveform::staticc::png_file::waveform_static_png_visualize;
// audio_visualizer has some cool convenient types that I reuse here
use audio_visualizer::{ChannelInterleavement, Channels};
use lowpass_filter::simple::sp::apply_lpf_i16_sp;
/// Minimal example how to use this crate/how to apply low pass filter.
fn main() {
// read this from MP3 for example
let audio_data_lrlr = [0_i16, 1, -5, 1551, 141, 24];
// split into left and right channel
// audio_visualizer has some cool convenient types that I reuse here
let (mut left, mut right) = Channels::Stereo(ChannelInterleavement::LRLR)
.stereo_interleavement()
.to_channel_data(&audio_data_lrlr);
// left
apply_lpf_i16_sp(&mut left, 44100, 120);
// right
apply_lpf_i16_sp(&mut right, 44100, 120);
// visualize effect as waveform in a PNG file
waveform_static_png_visualize(
&left,
Channels::Mono,
"test/out",
"example_waveform_lowpassed_left.png",
);
waveform_static_png_visualize(
&right,
Channels::Mono,
"test/out",
"example_waveform_lowpassed_right.png",
);
}
```
## Visual Examples
### #1: Original Waveform of a short sample
### #1: Lowpassed Waveform
### #2: Original Waveform of a song
### #2: Lowpassed Waveform
### #2: 3x Lowpassed Waveform
