From 849369d6c66d3054688672f97d31fceb8e8230fb Mon Sep 17 00:00:00 2001 From: root Date: Fri, 25 Dec 2015 04:40:36 +0000 Subject: initial_commit --- Documentation/DocBook/v4l/vidioc-cropcap.xml | 174 +++++++++++++++++++++++++++ 1 file changed, 174 insertions(+) create mode 100644 Documentation/DocBook/v4l/vidioc-cropcap.xml (limited to 'Documentation/DocBook/v4l/vidioc-cropcap.xml') diff --git a/Documentation/DocBook/v4l/vidioc-cropcap.xml b/Documentation/DocBook/v4l/vidioc-cropcap.xml new file mode 100644 index 00000000..816e90e2 --- /dev/null +++ b/Documentation/DocBook/v4l/vidioc-cropcap.xml @@ -0,0 +1,174 @@ + + + ioctl VIDIOC_CROPCAP + &manvol; + + + + VIDIOC_CROPCAP + Information about the video cropping and scaling abilities + + + + + + int ioctl + int fd + int request + struct v4l2_cropcap +*argp + + + + + + Arguments + + + + fd + + &fd; + + + + request + + VIDIOC_CROPCAP + + + + argp + + + + + + + + + Description + + Applications use this function to query the cropping +limits, the pixel aspect of images and to calculate scale factors. +They set the type field of a v4l2_cropcap +structure to the respective buffer (stream) type and call the +VIDIOC_CROPCAP ioctl with a pointer to this +structure. Drivers fill the rest of the structure. The results are +constant except when switching the video standard. Remember this +switch can occur implicit when switching the video input or +output. + + + struct <structname>v4l2_cropcap</structname> + + &cs-str; + + + &v4l2-buf-type; + type + Type of the data stream, set by the application. +Only these types are valid here: +V4L2_BUF_TYPE_VIDEO_CAPTURE, +V4L2_BUF_TYPE_VIDEO_OUTPUT, +V4L2_BUF_TYPE_VIDEO_OVERLAY, and custom (driver +defined) types with code V4L2_BUF_TYPE_PRIVATE +and higher. + + + struct v4l2_rect + bounds + Defines the window within capturing or output is +possible, this may exclude for example the horizontal and vertical +blanking areas. The cropping rectangle cannot exceed these limits. +Width and height are defined in pixels, the driver writer is free to +choose origin and units of the coordinate system in the analog +domain. + + + struct v4l2_rect + defrect + Default cropping rectangle, it shall cover the +"whole picture". Assuming pixel aspect 1/1 this could be for example a +640 × 480 rectangle for NTSC, a +768 × 576 rectangle for PAL and SECAM centered over +the active picture area. The same co-ordinate system as for + bounds is used. + + + &v4l2-fract; + pixelaspect + This is the pixel aspect (y / x) when no +scaling is applied, the ratio of the actual sampling +frequency and the frequency required to get square +pixels.When cropping coordinates refer to square pixels, +the driver sets pixelaspect to 1/1. Other +common values are 54/59 for PAL and SECAM, 11/10 for NTSC sampled +according to []. + + + +
+ + + + + struct <structname>v4l2_rect</structname> + + &cs-str; + + + __s32 + left + Horizontal offset of the top, left corner of the +rectangle, in pixels. + + + __s32 + top + Vertical offset of the top, left corner of the +rectangle, in pixels. + + + __s32 + width + Width of the rectangle, in pixels. + + + __s32 + height + Height of the rectangle, in pixels. Width +and height cannot be negative, the fields are signed for +hysterical reasons. + + + + +
+ + + + &return-value; + + + + EINVAL + + The &v4l2-cropcap; type is +invalid or the ioctl is not supported. This is not permitted for +video capture, output and overlay devices, which must support +VIDIOC_CROPCAP. + + + + + + + -- cgit v1.2.3