On Thursday, December 23, 2010 10:02:33 Laurent Pinchart wrote: > Hi Hans, > > On Monday 20 December 2010 14:09:40 Hans Verkuil wrote: > > On Monday, December 20, 2010 13:48:51 Laurent Pinchart wrote: > > > > > > What if the application wants to change the resolution during capture ? > > > It will have to stop capture, call REQBUFS(0), change the format, > > > request buffers and restart capture. If filehandle ownership is dropped > > > after REQBUFS(0) that will open the door to a race condition. > > > > That's why S_PRIORITY was invented. > > Right, I should implement that. I think the documentation isn't clear though. > What is the background priority for exactly ? As the documentation mentions, it can be used for background processes monitoring VBI (e.g. teletext) transmissions. I'm not aware of any such applications, though. PRIORITY_DEFAULT and PRIORITY_RECORD are the only two relevant prios in practice. > And the "unset" priority ? Internal prio only. I think it's the value when no file handle is open. > Are > other applications allowed to change controls when an application has the > record priority ? No. Only read-only ioctls can be executed. > In general I find the priority ioctls underspecified, that's why I haven't > implemented them yet. Use the prio support functions in v4l2-common. They are easy to use and do the job. Regards, Hans > On a side note, I've just tested the latest uvcvideo driver, and I've > successfully captured video using a second application after calling > REQBUFS(0) in a first application. > > -- Hans Verkuil - video4linux developer - sponsored by Cisco -- 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
