Hi Laurent, First, I hope to be good at the warsaw meeting. :) 2011-03-16 ìì 9:14, Laurent Pinchart ì ê: > Hi HeungJun, > > On Monday 14 March 2011 08:02:01 Kim, HeungJun wrote: >> Hi Laurent, >> >> I heard of that there was a chance between you and Sylwester telling about >> the menu entries focus, and so after that, probably this menu style of the >> patch I sent, need to be more upgraded. So, can you tell me the kind or >> sequence of the UVC device breifly? >> >> I guess the word *AUTO* at the UVC device means doing focus continuously, >> not once or one time. > > That's correct. In the UVC context, auto focus means CAF and manual focus > means... well, manual focus :-) > >> But, at the sensors I used the *AUTO* focus means doing focus once, on the >> other hand *CONTINUOUS* means doing continuously. So, we need to be clear >> terms about focus. >> >> At the sensor I used, the focus needs 3 kinds of commands: >> 1) setting mode >> >> : it makes the lens initial position for each AF(Normal, Continuous, >> : Night mode Focus, etc), >> >> and set the AF status Idle. >> 2) execute AF >> >> : doing the move of the lens >> >> 3) read AF status >> >> : checking the lens status(Focus failed, Focus success, Idle, Busy) >> >> and do the proper jobs. >> >> I don't know uvc case well, so, If you share about this, it can be help. > > What bothers me with your auto-focus implementation is that the user might > want to perform auto-focus several times. Let's imagine this use case: > > 1. The user points the camera (webcam, cellphone camera, digital camera, it > doesn't matter) at an object. > > 2. The user presses a button to perform singleshot auto-focus (it can be a > physical button or a button on the camera screen, once again it doesn't > matter). > > 3. The application sets the focus control to AUTO. > > 4. The driver and device perform auto-focus once. The lens is moved so that > the object is in focus. > > 5. The user points the camera at another object. > > 6. The user presses a button to perform singleshot auto-focus. > > 7. The applications sets the focus control to AUTO. As the focus control value > was already AUTO, nothing is done. > > This is clearly broken. That's why we need a V4L2 button control in addition > to the menu control. > Yes. Youre'rignt. The menu control dosen't called one more with the same value. It's now worked I know. But, the reason why I choose menu type for focus, is because the menu type can let the user-application know how many kinds of focus this sensor have & support, using querymenu. The only way letting know, is currently the menu type. On the other hand, not-working twice or more executions is handled by user-application. The user-application want twice auto focus, it calls AUTO-Manual-(or any other control value)-and AUTO once again. It's wierd, but It can satisfy application and drivers. And, but it might be irrelevant, the user-application(or upper layer platform) can determine how to draw & arrange the UI objects after it knows the kinds of focus method at last. It may be a time to need another type of control. And such control should satisfy these: 1. letting the user-application know how many kinds in the controls(like a querymenu) 2. being available to be called one more. How about your opinion? Regards, Heungjun Kim -- To unsubscribe from this list: send the line "unsubscribe linux-media" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
