Struct ResampleSpec 

pub struct ResampleSpec { /* private fields */ }

Available on crate feature resample only.

One end of a conversion: sample rate, sample format, channel layout.

Spelled in FFmpeg’s own vocabulary because construction is off the AudioResampler trait and this is the backend that has to be handed to swr_alloc_set_opts2. FfmpegResampler restates the source spec in the vocabulary a decoded frame carries, so the mid-stream check compares like with like without the caller ever seeing two dialects.

Implementations

impl ResampleSpec

pub const fn new(rate: u32, format: Sample, layout: ChannelLayout) -> Self

Constructs a spec from its three parts.

Deliberately total and const: a spec is a description, and describing something swr cannot convert is not itself an error. FfmpegResampler::new is the choke point every construction route passes through, and it is what refuses a rate, a format or a channel layout this backend cannot honour — see FfmpegResampler::new for the roster and ResampleError::UnsupportedLayout for why a layout can be refused at all.

pub fn from_parameters(parameters: &Parameters) -> Option<Self>

The spec a track declares, read off the codec parameters a crate::FfmpegDemuxer track row carries (track.extra().parameters()) — the “source from TrackInfo” path.

Returns None for a non-audio track, for one whose declared sample format is AV_SAMPLE_FMT_NONE (a codec whose format is only known once its decoder opens), and for a custom or ambisonic channel layout — see Self::from_decoder for the first case and the note on [unspecified_layout] for the last.

pub fn from_decoder(decoder: &Audio) -> Option<Self>

The spec an opened decoder will actually produce — its rate, sample format and channel layout, straight off the codec context.

Reach it through FfmpegAudioStreamDecoder::inner. None on a custom or ambisonic layout, and on a context whose sample format is still unset (a decoder that has not been opened).

pub fn unspecified_layout(channels: i32) -> ChannelLayout

A layout that names a channel count and nothing else — AV_CHANNEL_ORDER_UNSPEC.

Not a degenerate case: a WAV file without a WAVE_FORMAT_EXTENSIBLE channel mask genuinely declares no layout, and FFmpeg faithfully reports it as unspecified in the codec parameters, in the codec context, and on every decoded frame. Substituting a default layout would make the source spec disagree with the frames it is supposed to describe, and every send_frame would be refused as a mid-stream change. swr accepts an unspecified layout at either end and maps the channels positionally.

pub const fn rate(&self) -> u32

Sample rate in Hz.

pub const fn format(&self) -> Sample

Sample format.

pub const fn layout(&self) -> ChannelLayout

Channel layout.

pub fn channels(&self) -> i32

Channel count, from the layout.

Trait Implementations

impl Clone for ResampleSpec

fn clone(&self) -> ResampleSpec

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Copy for ResampleSpec

impl Debug for ResampleSpec

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

Formats the value using the given formatter.

impl Eq for ResampleSpec

impl PartialEq for ResampleSpec

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

Equality operator ==.

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

Inequality operator !=.

impl StructuralPartialEq for ResampleSpec