FFMPEG中lineSize，width，height之间的关系

Question

我在AVFrame中的linesize，height，width之间感到困惑。

根据我的理解，linesize是大步，理想情况下应该是图像的宽度，对吗？

但是，width和linesize的值不匹配。

AVFrame pFrame; 
cout<<"PFrame Linesize :"<<pFrame->data.linesize[0]<<endl;
cout<<"PFrame Width :"<<pFrame->width<<endl;

输出：

PFrame Linesize : 64
PFrame width : 12

我的画面尺寸为12 * 12。

根据这个post的答案，lineize应该与宽度相同。但我无法理解他们为何与众不同。

Answer 1

我在这里引用文档：

 * For video, size in bytes of each picture line.
 * For audio, size in bytes of each plane.
 *
 * For audio, only linesize[0] may be set. For planar audio, each channel
 * plane must be the same size.
 *
 * For video the linesizes should be multiples of the CPUs alignment
 * preference, this is 16 or 32 for modern desktop CPUs.
 * Some code requires such alignment other code can be slower without
 * correct alignment, for yet other it makes no difference.
 *
 * @note The linesize may be larger than the size of usable data -- there
 * may be extra padding present for performance reasons.

所以视频的线条化是

width * bytes per pixel + line padding

它会将您从一行图像/帧数据的开头带到下一行的开头。