Hi Andres,
In regards to your first question, it's a bit of both. Cameras support a maximum frame rate at any given resolution. A common example is 640x480 @ 30 FPS. This is heavily affected by the exposure setting however. Set the exposure past 33 ms, and it becomes physically impossible to capture at 30 FPS. So to answer your question, you set in the driver the frame rate you want, and based on its other settings the camera delivers the closest frame rate it can manage. In your application however, you have the option of not capturing as many frames as the camera delivers. I've written a number of programs where I set the camera to run at 30 FPS in the driver, but only display 10 FPS to the user. This can be accomplished using timers to only grab a frame from the camera ever x number of ms. Hopefully that helps, feel free to ask more questions if something isn't clear. -- Nathanael -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Andres Gonzalez Sent: Wednesday, October 31, 2007 5:46 PM To: [email protected] Subject: [Linux-uvc-devel] basic questions This is my first post here--not sure if this is the right place to ask these questions. If not, let me know. I have been playing around with V4L2 with a Logitech QuickCam Pro 4000 with the pwc driver. The VIDIOC_ENUM_FRAMESIZES and VIDIOC_ENUM_FRAMEINTERNALS ioctls do not seem to work. Consequently, I have some basic questions. 1) with V4L2, is the frame rate under the control of the driver or the application? That is, can the application simply grab the video data at whatever frame rate it wants? Or do you tell the driver what frame rate you want? 2) I just found out about UVC so I do not know much about it. Is UVC a replacement for the pwc driver I am currently using? I just signed up for the mailing list and I hope to learn a lot lurking around here. Thanks, -Andres _______________________________________________ Linux-uvc-devel mailing list [email protected] https://lists.berlios.de/mailman/listinfo/linux-uvc-devel
