Enum ChannelLayout 

#[non_exhaustive]
pub enum ChannelLayout {
    Mono,
    Stereo,
    Stereo21,
    Surround30,
    Quad,
    Surround40,
    Surround41,
    Surround50,
    Surround51,
    Surround60,
    Surround61,
    Surround70,
    Surround71,
    LoRo,
    LtRt,
    DiscreteN(u16),
}

Audio channel layout — names a fixed ordered tuple of speaker positions, OR carries a discrete fallback count when the layout is unknown / non-standard.

Channel orderings are taken from ITU-R BS.775 (5.1 / 7.1 surround reference) and SMPTE ST 2036-2 (audio channel ordering for UHDTV). For 5.1 the canonical order this crate adopts is L, R, C, LFE, Ls, Rs (the WAVEFORMATEXTENSIBLE / Vorbis / Opus convention). 7.1 extends that with Lb, Rb (back-rear pair).

The Stereo variant covers both regular two-channel stereo and the AC-3 / AC-4 matrix-encoded downmix carriers Lo/Ro (“two of”, downmix-compatible) and Lt/Rt (“matrix-encoded for Pro Logic extraction”); the dedicated [LoRo] / [LtRt] variants surface the distinction explicitly when a downstream filter or muxer needs it.

DiscreteN(n) is the catch-all for “we know there are n channels but no recognised layout” — used when a codec produces an unusual channel count (>8) or when the container failed to surface a layout flag. It is the only variant whose position() returns None.

Marked #[non_exhaustive] so additional standard layouts (Atmos 7.1.4, Auro-3D 9.1, …) can be added without breaking match-exhaustive downstream consumers.

Variants (Non-exhaustive)

Non-exhaustive enums could have additional variants added in future. Therefore, when matching against variants of non-exhaustive enums, an extra wildcard arm must be added to account for any future variants.

Mono

Mono (1ch): C.

Stereo

Stereo (2ch): L, R.

Stereo21

2.1 (3ch): L, R, LFE.

Surround30

3.0 surround (3ch): L, R, C.

Quad

Quadraphonic (4ch): L, R, Ls, Rs — no centre, side surrounds.

Surround40

4.0 surround per BS.775 (4ch): L, R, C, Cs — centre + back surround.

Surround41

4.1 surround (5ch): L, R, C, Cs, LFE.

Surround50

5.0 surround (5ch): L, R, C, Ls, Rs.

Surround51

5.1 surround (6ch): L, R, C, LFE, Ls, Rs.

Surround60

6.0 surround (6ch): L, R, C, Cs, Ls, Rs.

Surround61

6.1 surround (7ch): L, R, C, LFE, Cs, Ls, Rs.

Surround70

7.0 surround (7ch): L, R, C, Ls, Rs, Lb, Rb.

Surround71

7.1 surround (8ch): L, R, C, LFE, Ls, Rs, Lb, Rb.

LoRo

AC-3 / AC-4 Lo/Ro stereo downmix (2ch). Two-channel mix preserving downmix-compatibility coefficients; not matrix-encoded.

LtRt

AC-3 / AC-4 Lt/Rt stereo downmix (2ch). Two-channel matrix-encoded downmix carrying surround information for Dolby Pro Logic decoding.

DiscreteN(u16)

Discrete fallback: n channels with no recognised layout. Used for unusual / >8ch / unknown layouts surfaced by exotic codecs or containers that drop layout flags.

Implementations

impl ChannelLayout

pub fn channel_count(&self) -> u16

Number of channels in this layout.

pub fn positions(&self) -> &'static [ChannelPosition]

Speaker positions in canonical order. Returns an empty slice for DiscreteN since the layout is unknown — call positions_owned to get a Vec if you need to enumerate slots regardless of known/unknown status.

pub fn positions_owned(&self) -> Vec<ChannelPosition>

Owned position list. For known layouts this clones positions; for DiscreteN(n) it returns an empty Vec (positions remain unknown). Provided so callers that just want “give me positions for any layout” don’t have to special-case the discrete arm.

pub fn position(&self, idx: usize) -> Option<ChannelPosition>

Speaker position at slot idx in canonical order, or None for out-of-range slots and for DiscreteN (where the layout is unknown).

pub fn has_lfe(&self) -> bool

True when this layout carries a low-frequency-effects (LFE) channel.

pub fn is_surround(&self) -> bool

True when this layout carries surround information (more than two channels OR an LFE). Stereo / Mono return false; LoRo / LtRt are 2-channel downmixes and also return false even though they encode surround content (that’s the whole point of a downmix).

pub fn from_count(n: u16) -> ChannelLayout

Back-compat bridge: infer a layout from a bare channel count.

This mapping is what lets codecs that haven’t been updated to set a layout explicitly continue to work: they keep producing a count and we infer the most-common layout for that count. The choices follow industry defaults — 5.1 wins for 6ch (more common than 6.0), 7.1 wins for 8ch, and so on.

count	layout
1	Mono
2	Stereo
3	Surround30
4	Quad
5	Surround50
6	Surround51
7	Surround61
8	Surround71
other	DiscreteN

Trait Implementations

impl Clone for ChannelLayout

fn clone(&self) -> ChannelLayout

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Copy for ChannelLayout

impl Debug for ChannelLayout

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Display for ChannelLayout

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Eq for ChannelLayout

impl FromStr for ChannelLayout

type Err = ParseChannelLayoutError

The associated error which can be returned from parsing.

fn from_str(s: &str) -> Result<Self, Self::Err>

Parses a string s to return a value of this type.

impl Hash for ChannelLayout

fn hash<__H: Hasher>(&self, state: &mut __H)

Feeds this value into the given Hasher.

fn hash_slice<H>(data: &[Self], state: &mut H)

where H: Hasher, Self: Sized,

Feeds a slice of this type into the given Hasher.

impl PartialEq for ChannelLayout

fn eq(&self, other: &ChannelLayout) -> bool

Tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

Tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl StructuralPartialEq for ChannelLayout