v4l2ctl 0.1a5 documentation

What v4l2ctl is

v4l2ctl is a python package to control v4l2 drivers.

Project Status

The project is still in its early development stages. It can, however, already be used to read the name, driver, version and capabilities of a v4l2 device driver.

The documentation

v4l2ctl package

Module contents

class v4l2ctl.V4l2Device(device='/dev/video0')

Initialize the V4l2Device object and read its basic information.

Keyword Arguments:
 device (str, path-like, int) – the video device (default r”/dev/video0”) if an int is given, it is assumed to be number after “video” in “/dev”.
Raises:IoctlError – if a non-video device file is given.
buffer_type

The buffer type (see V4l2BufferType) required for several operations. This attribute does not change anything in the device itself. It is used by other operations.

bus

The bus through which this device is connected (read-only).

capabilities

The device specific capabilities (read-only). These are the capabilities associated with this dev-file only. The physical device can have more than one dev-file, and hence more capabilities. See physical_capabilities.

close()

Flush and close the IO object.

This method has no effect if the file is already closed.

cropping_capabilities

The cropping capabilities (read-only). These are the cropping capabilities of this video device.

Only valid for these buffer types:
  • V4l2BufferType.VIDEO_CAPTURE
  • V4l2BufferType.VIDEO_CAPTURE_MPLANE
  • V4l2BufferType.VIDEO_OUTPUT
  • V4l2BufferType.VIDEO_OUTPUT_MPLANE
  • V4l2BufferType.VIDEO_OVERLAY
cropping_rectangle

The cropping rectangle (see V4l2Rectangle).

Note

The cropping rectange is specfic to the set buffer type. (See buffer_type)

device

The device file (read-only).

driver

The linux driver (read-only).

fileno()

Returns underlying file descriptor if one exists.

OSError is raised if the IO object does not use a file descriptor.

flush()

Flush write buffers, if applicable.

This is not implemented for read-only and non-blocking streams.

formats

A generator for the suported formats by this video device.

Note

The formats are specfic to the set buffer type. (See buffer_type)

isatty()

Return whether this is an ‘interactive’ stream.

Return False if it can’t be determined.

iter_buffer_formats(buffer_type)

Iterate over the formats supported by a certain buffer.

Keyword Arguments:
 buffer_type – see V4l2BufferType.
Returns:a generator
static iter_devices(skip_links=True)

Return an iterator over the available v4l2 devices.

Keyword Arguments:
 skip_links (bool) – skip links and return every device only once (default True)
Returns:an iterator
name

The card name (read-only).

physical_capabilities

The general physical capabilities (read-only). These are the capabilities associated with the physical device as a while, and not limited to this dev-file only.

readable()

Return whether object was opened for reading.

If False, read() will raise OSError.

readline(size=-1)

Read and return a line from the stream.

If size is specified, at most size bytes will be read.

The line terminator is always b’n’ for binary files; for text files, the newlines argument to open can be used to select the line terminator(s) recognized.

readlines(hint=-1)

Return a list of lines from the stream.

hint can be specified to control the number of lines read: no more lines will be read if the total size (in bytes/characters) of all lines so far exceeds hint.

seekable()

Return whether object supports random access.

If False, seek(), tell() and truncate() will raise OSError. This method may need to do a test seek().

supported_buffer_types

The supported buffer types by this video device (read-only).

version

The kernel version as a string (read-only).

version_tuple

The kernel version as a tuple (read-only).

writable()

Return whether object was opened for writing.

If False, write() will raise OSError.

writelines(lines)

Write a list of lines to stream.

Line separators are not added, so it is usual for each of the lines provided to have a line separator at the end.

class v4l2ctl.V4l2Capabilities

The v4l2 capability flags.

These are the flags defining the supported capabilities of a V4l2 devince.

Example

Check if device /dev/video0 supports video capturing:

vid_dev = VideoDevice(r"/dev/video0")
if CapabilityFlags.VIDEO_CAPTURE in vid_dev.capabilities:
    start_recording()
ASYNCIO = 33554432

Async I/O.

AUDIO = 131072

Has audio support.

DEVICE_CAPS = 2147483648

Sets device capabilities field.

EXT_PIX_FORMAT = 2097152

Supports the extended pixel format.

HW_FREQ_SEEK = 1024

Can do hardware frequency seek.

META_CAPTURE = 8388608

Is a metadata capture device.

META_OUTPUT = 134217728

Is a metadata output device.

MODULATOR = 524288

Has a modulator.

RADIO = 262144

Is a radio device.

RDS_CAPTURE = 256

RDS data capture.

RDS_OUTPUT = 2048

Is an RDS encoder.

READWRITE = 16777216

Read/write systemcalls.

SDR_CAPTURE = 1048576

Is a SDR capture device.

SDR_OUTPUT = 4194304

Is a SDR output device.

SLICED_VBI_CAPTURE = 64

Is a sliced VBI capture device.

SLICED_VBI_OUTPUT = 128

Is a sliced VBI output device.

STREAMING = 67108864

Streaming I/O ioctls.

TOUCH = 268435456

Is a touch device.

TUNER = 65536

Has a tuner.

VBI_CAPTURE = 16

Is a raw VBI capture device.

VBI_OUTPUT = 32

Is a raw VBI output device.

VIDEO_CAPTURE = 1

Is a video capture device.

VIDEO_CAPTURE_MPLANE = 4096

Is a video capture device that supports multiplanar formats.

VIDEO_M2M = 32768

Is a video mem-to-mem device.

VIDEO_M2M_MPLANE = 16384

Is a video mem-to-mem device that supports multiplanar formats.

VIDEO_OUTPUT = 2

Is a video output device.

VIDEO_OUTPUT_MPLANE = 8192

Is a video output device that supports multiplanar formats.

VIDEO_OUTPUT_OVERLAY = 512

Can do video output overlay.

VIDEO_OVERLAY = 4

Can do video overlay.

class v4l2ctl.V4l2BufferType

The v4l2 buffer types.

Used with :attribute:`enum_fmt`.

META_CAPTURE = 13

Buffer for metadata capture, see Metadata Interface.

META_OUTPUT = 14

Buffer for metadata output, see Metadata Interface.

SDR_CAPTURE = 11

Buffer for Software Defined Radio (SDR) capture stream, see Software Defined Radio Interface (SDR).

SDR_OUTPUT = 12

Buffer for Software Defined Radio (SDR) output stream, see Software Defined Radio Interface (SDR).

SLICED_VBI_CAPTURE = 6

Buffer of a sliced VBI capture stream, see Sliced VBI Data Interface.

SLICED_VBI_OUTPUT = 7

Buffer of a sliced VBI output stream, see Sliced VBI Data Interface.

VBI_CAPTURE = 4

Buffer of a raw VBI capture stream, see Raw VBI Data Interface.

VBI_OUTPUT = 5

Buffer of a raw VBI output stream, see Raw VBI Data Interface.

VIDEO_CAPTURE = 1

Buffer of a single-planar video capture stream, see Video Capture Interface.

VIDEO_CAPTURE_MPLANE = 9

Buffer of a multi-planar video capture stream, see Video Capture Interface.

VIDEO_OUTPUT = 2

Buffer of a single-planar video output stream, see Video Output Interface.

VIDEO_OUTPUT_MPLANE = 10

Buffer of a multi-planar video output stream, see Video Output Interface.

VIDEO_OUTPUT_OVERLAY = 8

Buffer for video output overlay (OSD), see Video Output Overlay Interface.

VIDEO_OVERLAY = 3

Buffer for video overlay, see Video Overlay Interface.

class v4l2ctl.V4l2Formats

An Enum-Container for all V4l2Formats. This class delegates its operations to the contained enums. For more information, see:

py:class:V4l2PixFormats py:class:V4l2SdrFormats py:class:V4l2TouchFormats py:class:V4l2MetaFormats
class v4l2ctl.V4l2FormatDescFlags

The v4l2 format flags.

COMPRESSED = 1

This is a compressed format.

EMULATED = 2

This format is not native to the device but emulated through software (usually libv4l2), where possible try to use a native format instead for better performance.

NONE = 0

No flags are set.

exception v4l2ctl.IoctlError(device, name, request, return_code, extra_msg=None)

Raised when ioctl() returns a non-zero value.

exception v4l2ctl.FeatureNotSupported

Internal documentation

Internal documentation

This is the documentation of the internals of v4l2ctl

Module ioctlmacros

Module v4l2interface

Module v4l2device

exception v4l2ctl.v4l2device.FeatureNotSupported

Bases: Exception

__module__ = 'v4l2ctl.v4l2device'
__weakref__

list of weak references to the object (if defined)

class v4l2ctl.v4l2device.V4l2Device(device='/dev/video0')

Bases: io.IOBase

Initialize the V4l2Device object and read its basic information.

Keyword Arguments:
 device (str, path-like, int) – the video device (default r”/dev/video0”) if an int is given, it is assumed to be number after “video” in “/dev”.
Raises:IoctlError – if a non-video device file is given.
__abstractmethods__ = frozenset()
__enter__()
__exit__(exc_type, exc, tb)
__init__(device='/dev/video0')

Initialize self. See help(type(self)) for accurate signature.

__iter__()

Implement iter(self).

__module__ = 'v4l2ctl.v4l2device'
__next__()

Implement next(self).

__repr__()

Return repr(self).

_abc_impl = <_abc_data object>
_open()
buffer_type

The buffer type (see V4l2BufferType) required for several operations. This attribute does not change anything in the device itself. It is used by other operations.

bus

The bus through which this device is connected (read-only).

capabilities

The device specific capabilities (read-only). These are the capabilities associated with this dev-file only. The physical device can have more than one dev-file, and hence more capabilities. See physical_capabilities.

close()

Flush and close the IO object.

This method has no effect if the file is already closed.

closed
cropping_buffer_types = [<V4l2BufferType.VIDEO_CAPTURE: 1>, <V4l2BufferType.VIDEO_CAPTURE_MPLANE: 9>, <V4l2BufferType.VIDEO_OUTPUT: 2>, <V4l2BufferType.VIDEO_OUTPUT_MPLANE: 10>, <V4l2BufferType.VIDEO_OVERLAY: 3>]
cropping_capabilities

The cropping capabilities (read-only). These are the cropping capabilities of this video device.

Only valid for these buffer types:
  • V4l2BufferType.VIDEO_CAPTURE
  • V4l2BufferType.VIDEO_CAPTURE_MPLANE
  • V4l2BufferType.VIDEO_OUTPUT
  • V4l2BufferType.VIDEO_OUTPUT_MPLANE
  • V4l2BufferType.VIDEO_OVERLAY
cropping_rectangle

The cropping rectangle (see V4l2Rectangle).

Note

The cropping rectange is specfic to the set buffer type. (See buffer_type)

device

The device file (read-only).

driver

The linux driver (read-only).

fileno()

Returns underlying file descriptor if one exists.

OSError is raised if the IO object does not use a file descriptor.

flush()

Flush write buffers, if applicable.

This is not implemented for read-only and non-blocking streams.

formats

A generator for the suported formats by this video device.

Note

The formats are specfic to the set buffer type. (See buffer_type)

isatty()

Return whether this is an ‘interactive’ stream.

Return False if it can’t be determined.

iter_buffer_formats(buffer_type)

Iterate over the formats supported by a certain buffer.

Keyword Arguments:
 buffer_type – see V4l2BufferType.
Returns:a generator
static iter_devices(skip_links=True)

Return an iterator over the available v4l2 devices.

Keyword Arguments:
 skip_links (bool) – skip links and return every device only once (default True)
Returns:an iterator
name

The card name (read-only).

physical_capabilities

The general physical capabilities (read-only). These are the capabilities associated with the physical device as a while, and not limited to this dev-file only.

readable()

Return whether object was opened for reading.

If False, read() will raise OSError.

readline(size=-1)

Read and return a line from the stream.

If size is specified, at most size bytes will be read.

The line terminator is always b’n’ for binary files; for text files, the newlines argument to open can be used to select the line terminator(s) recognized.

readlines(hint=-1)

Return a list of lines from the stream.

hint can be specified to control the number of lines read: no more lines will be read if the total size (in bytes/characters) of all lines so far exceeds hint.

seekable()

Return whether object supports random access.

If False, seek(), tell() and truncate() will raise OSError. This method may need to do a test seek().

supported_buffer_types

The supported buffer types by this video device (read-only).

version

The kernel version as a string (read-only).

version_tuple

The kernel version as a tuple (read-only).

writable()

Return whether object was opened for writing.

If False, write() will raise OSError.

writelines(lines)

Write a list of lines to stream.

Line separators are not added, so it is usual for each of the lines provided to have a line separator at the end.

class v4l2ctl.v4l2device.V4l2DeviceIterator(skip_links)

Bases: object

__dict__ = mappingproxy({'__module__': 'v4l2ctl.v4l2device', '_v4l2_device_prefixes': ['video', 'radio', 'vbi', 'swradio', 'v4l-subdev'], '__init__': <function V4l2DeviceIterator.__init__>, '__iter__': <function V4l2DeviceIterator.__iter__>, '__dict__': <attribute '__dict__' of 'V4l2DeviceIterator' objects>, '__weakref__': <attribute '__weakref__' of 'V4l2DeviceIterator' objects>, '__doc__': None})
__init__(skip_links)

Initialize self. See help(type(self)) for accurate signature.

__iter__()
__module__ = 'v4l2ctl.v4l2device'
__weakref__

list of weak references to the object (if defined)

_v4l2_device_prefixes = ['video', 'radio', 'vbi', 'swradio', 'v4l-subdev']

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