Sensoray 2253 Linux - Manual (Page 15)

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SDK Reference
General Notes
Model 2253 device is accessed via /dev/videoX where X is the number
assigned to the device when it was plugged in. Three /dev/videoX nodes will
be created for each 2253 device. The first two video device nodes are for
video capture and the third is a video output. Which device the node
references can be determined by using the VIDIOC_QUERYCAP ioctl to
examine the card field for the serial no. The devices support multiple open,
allowing some parameters to be changed on-the-fly while another program is
accessing the device.
Driver Ioctl Reference
This reference is provided as a convenience to detail the 2253-specific
capabilities, without requiring the user to query the driver using the V4L2 API
or reading the driver source code. For a complete Video4Linux2 API reference,
please consult the LinuxTV.org web site.
(http://www.linuxtv.org/downloads/v4l-dvb-apis/)
All calls to ioctl function follow the same general approach.
The first parameter (fd) is a file descriptor returned by open(), which
specifies the addressed device.
The second parameter (request) is the request code, which specifies the
type of request.
The third parameter is a pointer to context-specific data.
All calls return 0 in case of success, or a negative value in case of an error.
The ioctls below are listed by the request parameter.
Driver-specific structures and request codes are defined in
driver/s2253ioctl.h.
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