函数 av_stereo3d_alloc_size 

pub unsafe extern "C" fn av_stereo3d_alloc_size(
    size: *mut usize,
) -> *mut AVStereo3D

Allocate an AVStereo3D structure and set its fields to default values. The resulting struct can be freed using av_freep().

@return An AVStereo3D filled with default values or NULL on failure.