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man pages section 4: Device and Network Interfaces

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Updated: Wednesday, July 27, 2022

usbvc (4D)


usbvc - USB video class driver


#include <sys/usb/clients/video/usbvc/usbvc.h>

#include <sys/videodev2.h>



The usbvc driver is a USBA (Solaris USB Architecture)-compliant client driver that supports the USB Device Class Definition for Video Devices specification, Versions 1.0 and 1.1. The usbvc driver supports a subset of the video controls and formats described in the USB specification.

The usbvc driver also implements the Video4Linux2 API (V4L2), Version 0.20 for applications. For more information on the V4L2 API, visit http://www.thedirks.org/v4l2 .

Note that the usbvc driver supports the video capture function only and that video output is not supported.

Reading Data

The usbvc driver reads video data from the isochronous endpoint of the device. Bulk data endpoints are not supported.

MJPEG and UNCOMPRESSED video formats are supported. Isochronous data are read from the isochronous input device frame-by-frame and are maintained in a buffer array within the driver. Video frames are read from the driver using the read(2) or mmap(2) I/O method. For read(2), each read returns a buffer of a video frame. For mmap(2), each VIDIOC_DQBUF ioctl returns the buffer structure v4l2_buffer. (A video frame buffer pointer is included in the structure). See the V4L2 API for buffer structure and other related data structure information.


A brief overview of supported ioctl requests appears below. For more detailed information, refer to the V4L2 API document. Note: ioctl information presented in the V4L2 API document may differ slightly from the content of this manpage. In such cases, you should rely on the information in this manpage.


Query the device capabilities. Besides device capabilities, the usbvc driver returns structure v4l2_capability which includes information on the driver, data bus and OS kernel. The Version structure member has no meaning in Solaris and is always set to 1.


Enumerate the video formats supported by the device.


Set a video format.


Get a video format.


Request the usbvc driver to allocate video data buffers. If a buffer is set to zero, the driver stops reading video data from the device and releases all allocated buffers. (For mmap(2) only).


Query a given buffer's status. (For mmap(2) only).


Enqueue an empty buffer to the video data buffer array. (For mmap(2) only).


Dequeue a done buffer from the video data buffer array. (For mmap(2) only).


Start reading video data.


Stop reading video data.


Enumerate all device inputs. Currently, the usbvc driver supports one input only.


Get the device's current input. At this time, the usbvc driver supports one input only.


Set the device's current input. At this time, the usbvc driver supports one input only.


Query the device and driver for supported video controls. Currently, the usbvc driver supports the brightness, contrast, saturation, hue, and gamma video controls.


Get the device's current video control.


Set the device's current video control.


Get streaming parameters, the number of frames per second and number of buffers used internally by driver in read/write mode.


Set streaming parameters, the number of frames per second and number of buffers used internally by driver in read/write mode.



An open was attempted after the device has already been opened.


An unsupported ioctl is received or an ioctl is attempted with an out-of-range value.


The driver received an unrecoverable device error or the device did not respond or the device stalled when attempting an access. A read(2) or ioctl(2) did not complete due to a peripheral access.


The driver received an open(2) request for a device for which the attach failed.


The driver received an open(2) request for a disconnected device.



64-bit ELF kernel module. (x86)


64-bit ELF kernel module. (SPARC)


ugen(4D) nodes.


Device node for isochronous input from USB video device and device control.


See attributes(7) for descriptions of the following attributes:

SPARC, x86, PCI-based systems

See Also

ioctl(2), mmap(2), open(2), read(2), libusb(3lib), ugen(4D), usba(4D), attributes(7), cfgadm_usb(8), attach(9E)

Writing Device Drivers in Oracle Solaris 11.4

Universal Serial Bus Specification 1.0, 1.1 and 2.0— 1996, 1998, 2000

USB Device Class Definition for Video Devices 1.0 and 1.1— 2003, 2005

Video4Linux2 API (V4L2), Version 0.20



In addition to being logged, the following messages may appear on the system console. All messages are formatted in the following manner:

Warning: <device path> (usbvc<instance num>):Error Message...
Device was disconnected while open. Data may have been lost.

The device has been hot-removed or powered off while it was open and a possible data transfer was in progress. The job may be aborted.

Cannot access <device>. Please reconnect.

This device has been disconnected because a device other than the original one has been inserted. The driver informs you of this fact by displaying the name of the original device.

Device is not identical to the previous one on this port. Please disconnect and reconnect.

The device was hot-removed while open. A new device was hot-inserted which is not identical to the original device. Please disconnect the device and reconnect the original device to the same port.


The USB video device will be power-managed when the device is idle.

If a USB video device is hot-removed while active, a console warning is displayed requesting you to put the device back in the same port and telling you of potential data loss. Hot-removal of an active video device is strongly discouraged.

Always close all applications before hot-removing or hot-inserting a device. If an application is open when a device is hot-removed, inserting the device in a different port will create new /dev/videoN links. Moving an active device to another port is not recommended.