Gerd Knorr wrote: >> 4. I don't understand 'timeperframe'. We already have v4l2_standard, >> shouldn't it just be retrieved from that? >> >> >Hmm, bttv implements it this way ... > > v4l2_video_std_construct(&s, bttv_tvnorms[btv->tvnorm].v4l2_id); > parm->parm.capture.timeperframe = v4l2_video_std_tpf(&s); > >... which clearly indicates it is indeed redundant. At least for TV >cards, what about usb webcams? > > That reminds me, how should (digital) USB webcams implement VIDIOC_ENUMSTD? Should they set std.id = V4L2_STD_UNKNOWN? Should they just return -EINVAL? Or should we have have a V4L2_STD_DIGITAL_CAM for devices where modulation standards and fixed frame rates don't apply?
And to answer your question, with USB webcams you cannot infer the timeperframe from any other fields in the V4L(2) API. The frame rate depends on many different factors including resolution, allocated USB bandwidth, palette, etc... The app should just request a target frame rate and the camera should do it's best to stay above (or below?) that. Oh, and speaking of digital things, will there be V4L2_STD #defines for the various digital broadcast standards? Or should we create a new ioctl for that? -- Mark McClelland [EMAIL PROTECTED] _______________________________________________ Video4linux-list mailing list [EMAIL PROTECTED] https://listman.redhat.com/mailman/listinfo/video4linux-list
