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¶