结构体 AVRegionOfInterest 

#[repr(C)]
pub struct AVRegionOfInterest {
    pub self_size: u32,
    pub top: c_int,
    pub bottom: c_int,
    pub left: c_int,
    pub right: c_int,
    pub qoffset: AVRational,
}

Structure describing a single Region Of Interest.

When multiple regions are defined in a single side-data block, they should be ordered from most to least important - some encoders are only capable of supporting a limited number of distinct regions, so will have to truncate the list.

When overlapping regions are defined, the first region containing a given area of the frame applies.

Fields

self_size: u32

Must be set to the size of this data structure (that is, sizeof(AVRegionOfInterest)).

top: c_int

Distance in pixels from the top edge of the frame to the top and bottom edges and from the left edge of the frame to the left and right edges of the rectangle defining this region of interest.

The constraints on a region are encoder dependent, so the region actually affected may be slightly larger for alignment or other reasons.

bottom: c_int

left: c_int

right: c_int

qoffset: AVRational

Quantisation offset.

Must be in the range -1 to +1. A value of zero indicates no quality change. A negative value asks for better quality (less quantisation), while a positive value asks for worse quality (greater quantisation).

The range is calibrated so that the extreme values indicate the largest possible offset - if the rest of the frame is encoded with the worst possible quality, an offset of -1 indicates that this region should be encoded with the best possible quality anyway. Intermediate values are then interpolated in some codec-dependent way.

For example, in 10-bit H.264 the quantisation parameter varies between -12 and 51. A typical qoffset value of -1/10 therefore indicates that this region should be encoded with a QP around one-tenth of the full range better than the rest of the frame. So, if most of the frame were to be encoded with a QP of around 30, this region would get a QP of around 24 (an offset of approximately -1/10 * (51 - -12) = -6.3). An extreme value of -1 would indicate that this region should be encoded with the best possible quality regardless of the treatment of the rest of the frame - that is, should be encoded at a QP of -12.

trait 实现

impl Clone for AVRegionOfInterest

fn clone(&self) -> AVRegionOfInterest

Returns a duplicate of the value. 阅读更多

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

从 source 执行拷贝赋值。 阅读更多

impl Debug for AVRegionOfInterest

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

使用给定的格式化器格式化该值。 阅读更多

impl PartialEq for AVRegionOfInterest

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

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

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

测试 !=。默认实现几乎总是足够的，没有充分理由不应被重写。

impl Copy for AVRegionOfInterest

impl Eq for AVRegionOfInterest

impl StructuralPartialEq for AVRegionOfInterest