Re: [Linux-uvc-devel] Frame Rate control?

[Laurent P. <lau...@sk...>]

Hi Phil,

>  Quick question.. is it possible to control the frame rate of a UVC
> device? I had a quick look at the spec but I didn't see anything. It's
> probable I'm missing the obvious...

It's possible, but not implemented yet due to a problem with the V4L2 specs. 
The issue is that UVC negociates the image size before the frame rate, while 
V4L2 negociates the frame rate before the image size (this is not entirely 
true, you can set the image size before the frame rate, but the required 
buffer length is returned by the image size negociation process, but UVC 
devices return the required buffer length when negociating the frame rate and 
compression quality). This has been discussed on the V4L2 mailing list, and I 
still have to write a proposal for a new IOCTL. This means applications will 
need to be upgraded to support the new interface.

Laurent Pinchart