moq-audio 0.1.10

Native audio encoding/decoding for Media over QUIC
Documentation 
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55

//! Uncompressed little-endian `f32` PCM, which needs no codec at all.

use super::Backend;
use crate::encode::{Encoded, Settings};
use crate::{Error, Layout, pcm};

pub(super) const NAME: &str = "pcm";

pub(super) struct Pcm {
	bitrate: u64,
}

impl Pcm {
	/// The catalog carries only a channel count, so a named layout that count
	/// would decode as another one is refused rather than relabeled.
	pub(super) fn open(settings: &Settings) -> Result<Box<dyn Backend>, Error> {
		let layout = settings.layout;
		if !matches!(layout, Layout::Discrete(_)) && Layout::from_channels(layout.channels())? != layout {
			return Err(Error::Unsupported(format!(
				"pcm carries only a channel count, which decodes as {:?}, not {layout:?}",
				Layout::from_channels(layout.channels())?
			)));
		}
		let bitrate = pcm::bitrate(settings.sample_rate, settings.layout.channels())?;
		Ok(Box::new(Self { bitrate }))
	}
}

impl Backend for Pcm {
	fn encode(&mut self, pcm: &[f32]) -> Result<Encoded, Error> {
		let mut payload = Vec::with_capacity(std::mem::size_of_val(pcm));
		for sample in pcm {
			payload.extend_from_slice(&sample.to_le_bytes());
		}
		Ok(Encoded::new(payload.into()))
	}

	fn reset(&mut self) {}

	fn set_bitrate(&mut self, _bitrate: u64) -> Result<(), Error> {
		Err(Error::Unsupported("pcm bitrate is fixed".into()))
	}

	fn bitrate(&self) -> u64 {
		self.bitrate
	}

	fn delay(&self) -> usize {
		0
	}

	fn name(&self) -> &str {
		NAME
	}
}