Can we put capture frame from USB camera directly to user-space memory instead of passing it through v4l2_buffer?

Question

I came to know upon reading that USB camera captured frame is first stored in v4l2_buffer and then it is pass to user-space buffer(using VIDIOC_DQBUF ioctl call).But I want to know that can we directly pass the frame to the user defined buffer instead of v4l2_buffer?

Also want to know can we modify the ioctl calls related to USB camera capture like VIDIOC_REQBUF,VIDIOC_QBUF,etc.?

Also can someone tell me where will be v4l2_buffer located?Whether it will be in kerenl or user-space?And if it is located in kernel space,can we change it to user-space or not?

Any help in this questions will be appreciated..

Thanks!