GstVaapiDownload — A VA to video flow filter
GstVaapiDownload;
GObject +----GstObject +----GstElement +----GstBaseTransform +----GstVaapiDownload
GstVaapiDownload implements GstImplementsInterface and GstVideoContext.
vaapidownload converts from VA surfaces to raw YUV pixels.
typedef struct _GstVaapiDownload GstVaapiDownload;