xiaoxiang781216 commented on PR #12829:
URL: https://github.com/apache/nuttx/pull/12829#issuecomment-2267274004

   > Hi @acassis, I've took a look at video drivers. I cannot say I fully 
understand how a camera should work, not the driver implementation but how to 
use it from user space perspective. I do expect differences from an char 
driver, though I cannot say what the differences should be.
   
   Actually, video driver framework is still char device, the difference is 
that ioctl is standardize which mean:
   
   1. All drivers implement the same ioctl
   2. We can write general apps to control the different camera sensor/isp 
without change
   
   > Could you help me out with an explication, guide, or point me into the 
direction I should look at?
   
   NuttX camera/video driver follow Linux v4l2 driver from userspace 
perspective (e.g. ffmpeg v4l2 driver could work with NuttX camera/codec driver 
without any changing). So, you can learn how NuttX camere/video driver work 
from v4l2 related documentation.
   
   > I saw the camera example from nuttx-apps, but I do not understand if that 
should be an general example (over all driver that implements camera ops), or 
is an specific implementation over some camera drivers.
   
   https://github.com/apache/nuttx-apps/tree/master/system/nxcamera is another 
example.
   
   


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