* Range values for V4L2_CID_* commands @ 2020-07-10 14:18 Lucas 2020-07-10 14:28 ` Hans Verkuil 0 siblings, 1 reply; 3+ messages in thread From: Lucas @ 2020-07-10 14:18 UTC (permalink / raw) To: linux-media Hello, how do I obtain the accepted range of values for each V4L2_CID command? Take V4L2_CID_BRIGHTNESS as an example, how do I know what is the maximum and minimum values accepted for it? I have tried to use 'v4l2_ioctl(fd, VIDIOC_G_CTRL, &query);' thinking that would be stored in the maximum and minimum members for the struct v4l2_queryctrl but that does not appear to be the case as the values for those members are always zero. Thank you. ^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: Range values for V4L2_CID_* commands 2020-07-10 14:18 Range values for V4L2_CID_* commands Lucas @ 2020-07-10 14:28 ` Hans Verkuil 2020-07-10 14:36 ` Lucas 0 siblings, 1 reply; 3+ messages in thread From: Hans Verkuil @ 2020-07-10 14:28 UTC (permalink / raw) To: Lucas, linux-media On 10/07/2020 16:18, Lucas wrote: > Hello, how do I obtain the accepted range of values for each V4L2_CID > command? Take V4L2_CID_BRIGHTNESS as an example, how do I know what is > the maximum and minimum values accepted for it? I have tried to use > 'v4l2_ioctl(fd, VIDIOC_G_CTRL, &query);' thinking that would be stored > in the maximum and minimum members for the struct v4l2_queryctrl but > that does not appear to be the case as the values for those members are > always zero. Use VIDIOC_QUERYCTRL for that. See: https://linuxtv.org/downloads/v4l-dvb-apis-new/userspace-api/v4l/vidioc-queryctrl.html Regards, Hans ^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: Range values for V4L2_CID_* commands 2020-07-10 14:28 ` Hans Verkuil @ 2020-07-10 14:36 ` Lucas 0 siblings, 0 replies; 3+ messages in thread From: Lucas @ 2020-07-10 14:36 UTC (permalink / raw) To: Hans Verkuil, linux-media Thank you kind sir. On 10/07/2020 11:28, Hans Verkuil wrote: > On 10/07/2020 16:18, Lucas wrote: >> Hello, how do I obtain the accepted range of values for each V4L2_CID >> command? Take V4L2_CID_BRIGHTNESS as an example, how do I know what is >> the maximum and minimum values accepted for it? I have tried to use >> 'v4l2_ioctl(fd, VIDIOC_G_CTRL, &query);' thinking that would be stored >> in the maximum and minimum members for the struct v4l2_queryctrl but >> that does not appear to be the case as the values for those members are >> always zero. > Use VIDIOC_QUERYCTRL for that. See: > > https://linuxtv.org/downloads/v4l-dvb-apis-new/userspace-api/v4l/vidioc-queryctrl.html > > Regards, > > Hans ^ permalink raw reply [flat|nested] 3+ messages in thread
end of thread, other threads:[~2020-07-10 14:36 UTC | newest] Thread overview: 3+ messages (download: mbox.gz follow: Atom feed -- links below jump to the message on this page -- 2020-07-10 14:18 Range values for V4L2_CID_* commands Lucas 2020-07-10 14:28 ` Hans Verkuil 2020-07-10 14:36 ` Lucas
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