Enum ChannelLayoutFault 

#[non_exhaustive]
pub enum ChannelLayoutFault {
    UnverifiableCustomMap {
        channels: i32,
    },
    MalformedCustomMap {
        channels: i32,
    },
    MalformedLayout {
        order: i32,
        channels: i32,
    },
    Alloc,
}

Why a channel layout could not be described.

Three answers, and the first two are memory-safety ones rather than resource ones. av_channel_layout_describe walks u.map[i] for each of nb_channels when the order is CUSTOM, and FFmpeg’s struct puts nothing between a caller and that walk: the map is a bare pointer and the count is a bare int. Refusing is not politeness, it is the precondition.

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.

UnverifiableCustomMap

A CUSTOM order reached a safe conversion, which cannot establish that the map it points at is as long as the count it declares.

ffmpeg_next::ChannelLayout is a public newtype over a public AVChannelLayout, so safe Rust can write nb_channels = 2 beside a u.map that points at one entry — or at a dangling address, or at something misaligned. Checking for null and for a terminator inside each name does not help: neither provenance nor extent is observable from the pointer, and the loop that would check the names is itself the out-of-bounds read. There is no validation a safe function can perform here, so it performs none and refuses.

The extent has to come from the caller instead, which is what channel_layout_description_from_raw_ptr’s unsafe contract asks for. Inside this crate the demux and convert roads satisfy it from FFmpeg’s own AVCodecParameters and AVFrame, where av_channel_layout_copy allocated the map and sized it — and they argue exactly that at each call.

Fields

channels: i32

nb_channels, as the layout declared it.

MalformedCustomMap

A CUSTOM order whose u.map is null, or whose channel count is not positive, or one of whose sixteen-byte names carries no NUL. FFmpeg would dereference the map, or read past a name, while describing it.

Fields

channels: i32

nb_channels, as the layout declared it.

MalformedLayout

A layout whose declared shape is not one FFmpeg’s own helpers can be given, for an order other than CUSTOM.

av_channel_layout_describe and av_channel_layout_compare both assume the invariants av_channel_layout_check states, and nothing between a caller and those helpers enforces them: a NATIVE layout whose nb_channels disagrees with its mask’s population, an AMBISONIC layout whose channels do not form an ambisonic order, and any layout declaring a count outside the range every downstream calculation assumes. FFmpeg computes nb_channels - popcount(mask) and takes an integer square root of it in signed C arithmetic; a count a safe caller can simply write into the public struct is enough to take that somewhere it was never meant to go.

Fields

order: i32

order, as the raw c_int it is on the wire.

channels: i32

nb_channels, as the layout declared it.

Alloc

The description could not be allocated.

Trait Implementations

impl Clone for ChannelLayoutFault

fn clone(&self) -> ChannelLayoutFault

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Copy for ChannelLayoutFault

impl Debug for ChannelLayoutFault

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

Formats the value using the given formatter.

impl Display for ChannelLayoutFault

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

Formats the value using the given formatter.

impl Eq for ChannelLayoutFault

impl Error for ChannelLayoutFault

fn source(&self) -> Option<&(dyn Error + 'static)>

Returns the lower-level source of this error, if any.

fn description(&self) -> &str

👎Deprecated since 1.42.0:

use the Display impl or to_string()

fn cause(&self) -> Option<&dyn Error>

👎Deprecated since 1.33.0:

replaced by Error::source, which can support downcasting

fn provide<'a>(&'a self, request: &mut Request<'a>)

🔬This is a nightly-only experimental API. (error_generic_member_access)

Provides type-based access to context intended for error reports.

impl PartialEq for ChannelLayoutFault

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

Equality operator ==.

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

Inequality operator !=.

impl StructuralPartialEq for ChannelLayoutFault