Enum RateControl 

pub enum RateControl {
    Vbr,
    ConstrainedVbr,
    Cbr,
}

How the encoder is allowed to vary the size of each packet.

Opus is a variable-rate codec, and the bitrate a caller sets is an average the encoder spends around rather than a size it emits every time. This chooses how much it is allowed to deviate.

ConstrainedVbr is the default, and matches libopus. The difference from Vbr only shows up on content whose difficulty changes quickly: constrained VBR keeps a reservoir so that any window of packets stays near the target, which is what a network with a fixed budget needs, while unconstrained VBR spends whatever a frame is worth. For encoding a file, where nothing downstream is metering the rate, unconstrained is usually the better picture per byte — it is what opusenc uses by default.

Variants

Vbr

Spend what each frame is worth, with no reservoir. Best quality per byte over a whole file; the instantaneous rate can wander a long way from the target.

ConstrainedVbr

Vary per packet, but hold a reservoir so any short window stays near the target. The default, and libopus’s.

Cbr

One size for every packet. Costs roughly a twelfth of the working bitrate against the other two, because the encoder can no longer move bits from an easy frame to a hard one; pick it only when something downstream genuinely needs a fixed packet size.

Trait Implementations

impl Clone for RateControl

fn clone(&self) -> RateControl

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Copy for RateControl

impl Debug for RateControl

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

Formats the value using the given formatter.

impl Eq for RateControl

impl PartialEq for RateControl

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

Equality operator ==.

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

Inequality operator !=.

impl StructuralPartialEq for RateControl