libcamera::V4L2PixelFormat Class Reference

V4L2 pixel format FourCC wrapper. More...

Classes
struct	Info
	Information about a V4L2 pixel format. More...

Public Member Functions
	V4L2PixelFormat ()
	Construct a V4L2PixelFormat with an invalid format. More...
	V4L2PixelFormat (uint32_t fourcc)
	Construct a V4L2PixelFormat from a FourCC value. More...
bool	isValid () const
	Check if the pixel format is valid. More...
uint32_t	fourcc () const
	Retrieve the pixel format FourCC numerical value. More...
	operator uint32_t () const
	Convert to the pixel format FourCC numerical value. More...
std::string	toString () const
	Assemble and return a string describing the pixel format. More...
const char *	description () const
	Retrieve the V4L2 description for the format. More...
PixelFormat	toPixelFormat (bool warn=true) const
	Convert the V4L2 pixel format to the corresponding PixelFormat. More...

Static Public Member Functions
static const std::vector< V4L2PixelFormat > &	fromPixelFormat (const PixelFormat &pixelFormat)
	Retrieve the list of V4L2PixelFormat associated with pixelFormat. More...

Detailed Description

V4L2 pixel format FourCC wrapper.

The V4L2PixelFormat class describes the pixel format of a V4L2 buffer. It wraps the V4L2 numerical FourCC, and shall be used in all APIs that deal with V4L2 pixel formats. Its purpose is to prevent unintentional confusion of V4L2 and DRM FourCCs in code by catching implicit conversion attempts at compile time.

To achieve this goal, construction of a V4L2PixelFormat from an integer value is explicit. To retrieve the integer value of a V4L2PixelFormat, both the explicit value() and implicit uint32_t conversion operators may be used.

Constructor & Destructor Documentation

V4L2PixelFormat() [1/2]

libcamera::V4L2PixelFormat::V4L2PixelFormat ( )

inline

Construct a V4L2PixelFormat with an invalid format.

V4L2PixelFormat instances constructed with the default constructor are invalid, calling the isValid() function returns false.

V4L2PixelFormat() [2/2]

libcamera::V4L2PixelFormat::V4L2PixelFormat ( uint32_t  fourcc )

inlineexplicit

Construct a V4L2PixelFormat from a FourCC value.

Parameters

[in]

fourcc

The pixel format FourCC numerical value

Member Function Documentation

description()

const char * libcamera::V4L2PixelFormat::description

(

)

const

Retrieve the V4L2 description for the format.

The description matches the value used by the kernel, as would be reported by the VIDIOC_ENUM_FMT ioctl.

Returns

The V4L2 description corresponding to the V4L2 format, or a placeholder description if not found

fourcc()

uint32_t libcamera::V4L2PixelFormat::fourcc ( ) const

inline

Retrieve the pixel format FourCC numerical value.

Returns

The pixel format FourCC numerical value

fromPixelFormat()

const std::vector< V4L2PixelFormat > & libcamera::V4L2PixelFormat::fromPixelFormat ( const PixelFormat &  pixelFormat )

static

Retrieve the list of V4L2PixelFormat associated with pixelFormat.

Parameters

[in]

pixelFormat

The PixelFormat to convert

Multiple V4L2 formats may exist for one PixelFormat as V4L2 defines separate 4CCs for contiguous and non-contiguous versions of the same image format.

Returns

The list of V4L2PixelFormat corresponding to pixelFormat

isValid()

bool libcamera::V4L2PixelFormat::isValid ( ) const

inline

Check if the pixel format is valid.

V4L2PixelFormat instances constructed with the default constructor are invalid. Instances constructed with a FourCC defined in the V4L2 API are valid. The behaviour is undefined otherwise.

Returns

True if the pixel format is valid, false otherwise

operator uint32_t()

libcamera::V4L2PixelFormat::operator uint32_t ( ) const

inline

Convert to the pixel format FourCC numerical value.

Returns

The pixel format FourCC numerical value

toPixelFormat()

PixelFormat libcamera::V4L2PixelFormat::toPixelFormat

(

bool

warn = true

)

const

Convert the V4L2 pixel format to the corresponding PixelFormat.

Parameters

[in]

warn

When true, log a warning message if the V4L2 pixel format isn't known

Users of this function might try to convert a V4L2PixelFormat to a PixelFormat just to check if the format is supported or not. In that case, they can suppress the warning message by setting the warn argument to false to not pollute the log with unnecessary messages.

Returns

The PixelFormat corresponding to the V4L2 pixel format

toString()

std::string libcamera::V4L2PixelFormat::toString

(

)

const

Assemble and return a string describing the pixel format.

Returns

A string describing the pixel format

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The documentation for this class was generated from the following files:

• include/libcamera/internal/v4l2_pixelformat.h
• src/libcamera/v4l2_pixelformat.cpp