Struct spa_io_rate_match

#[repr(C)]
pub struct spa_io_rate_match {
    pub delay: u32,
    pub size: u32,
    pub rate: f64,
    pub flags: u32,
    pub delay_frac: i32,
    pub padding: [u32; 6],
}

Rate matching.

It is usually set on the nodes that process resampled data, by the component (audioadapter) that handles resampling between graph and node rates. The \a flags and \a rate fields may be modified by the node.

The node can request a correction to the resampling rate in its process(), by setting \ref SPA_IO_RATE_MATCH_ACTIVE on \a flags, and setting \a rate to the desired rate correction. Usually the rate is obtained from DLL or other adaptive mechanism that e.g. drives the node buffer fill level toward a specific value.

When resampling to (graph->node) direction, the number of samples produced by the resampler varies on each cycle, as the rates are not commensurate.

When resampling to (node->graph) direction, the number of samples consumed by the resampler varies. Node output ports in process() should produce \a size number of samples to match what the resampler needs to produce one graph quantum of output samples.

Resampling filters introduce processing delay, given by \a delay and \a delay_frac, in samples at node rate. The delay varies on each cycle e.g. when resampling between noncommensurate rates.

The first sample output (graph->node) or consumed (node->graph) by the resampler is offset by \a delay + \a delay_frac / 1e9 node samples relative to the nominal graph cycle start position:

\code{.unparsed} first_resampled_sample_nsec = first_original_sample_nsec

• (rate_match->delay * SPA_NSEC_PER_SEC + rate_match->delay_frac) / node_rate \endcode

Fields

delay: u32

< resampling delay, in samples at node rate

size: u32

< requested input size for resampler

rate: f64

< rate for resampler (set by node)

flags: u32

< extra flags (set by node)

delay_frac: i32

< resampling delay fractional part, in units of nanosamples (1/10^9 sample) at node rate

padding: [u32; 6]

Trait Implementations

impl Clone for spa_io_rate_match

fn clone(&self) -> spa_io_rate_match

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for spa_io_rate_match

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

Formats the value using the given formatter.

impl PartialEq for spa_io_rate_match

fn eq(&self, other: &spa_io_rate_match) -> 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 Copy for spa_io_rate_match

impl StructuralPartialEq for spa_io_rate_match