C++ reference¶

This is for the most part identical to the Python reference, so much of the descriptions are not here, The descriptions are mostly for the parts that differ from the Python interface.

Devices¶

Device¶

class Device¶

Subclassed by qamlib::StreamingDevice

Public Functions

std::map<std::string, std::shared_ptr<Control>> list_controls()¶

virtual void set_control(const std::string &name, int value)¶: Set named control to value

void set_control(uint32_t id, int value)¶: Set control of id to value

int get_control(const std::string &name)¶

int get_control(uint32_t id)¶

void set_ext_control(const std::string &name, ControlValue &value)¶

std::unique_ptr<ControlValue> get_ext_control(const std::string &name, bool default_value = false)¶

std::map<std::string, std::unique_ptr<ControlValue>> get_controls(std::vector<std::string> names, bool default_value = false)¶

void set_controls(std::map<std::string, ControlValue*> values)¶

inline virtual ~Device()¶

Public Members

DeviceInfo device_info¶

StreamingDevice¶

class StreamingDevice : public qamlib::Device ¶

Subclassed by qamlib::Camera

Public Functions

virtual void start()¶

virtual void stop()¶

std::tuple<uint32_t, uint32_t> get_resolution()¶

std::tuple<uint32_t, uint32_t> set_resolution(uint32_t newWidth, uint32_t newHeight)¶

std::vector<Rectangle> get_crop()¶

void set_crop(int left, int top, uint32_t width, uint32_t height)¶

void set_crop(Rectangle rectangle)¶

void set_crop(std::vector<Rectangle> rectangles)¶

Rectangle get_crop_default()¶

Rectangle get_crop_bounds()¶

std::map<std::string, ImageFormat> list_formats()¶

Camera¶

class Camera : public qamlib::StreamingDevice ¶

Class for interacting with a V4L2 capture device.

Public Functions

inline Camera(const std::string &device, std::optional<uint32_t> buffers = std::nullopt, bool overflow_exception = true)¶

inline Camera(uint32_t device_num, std::optional<uint32_t> buffers = std::nullopt, bool overflow_exception = true)¶

inline Camera(bool overflow_exception = true)¶

inline ~Camera() override¶

virtual void start() override¶: Start streaming from the camera

virtual void stop() override¶: Stop streaming from the camera

std::tuple<struct FrameMetadata, cv::Mat> get_frame(std::optional<double> timeout = std::nullopt, bool buffered = false)¶

Get latest frame from the camera as a OpenCV Mat object.

Parameters:

timeout – Time in seconds to wait before throwing a TimeoutException. If 0 then there is no timeout.
buffered – If true then the first frame in the buffer is returned, if false then the latest frame is returned.

std::unique_ptr<Format> get_format()¶

std::unique_ptr<Format> set_format(Format &format)¶

std::unique_ptr<Format> set_format(const std::string &format, bool big_endian = false)¶

std::unique_ptr<FrameRate> get_framerates()¶

std::unique_ptr<FrameRate> get_framerates(uint32_t width, uint32_t height)¶

std::unique_ptr<FrameRate> get_framerates(uint32_t width, uint32_t height, const std::string &format, bool big_endian = false)¶

double get_framerate()¶

double set_framerate(double value)¶

Controls¶

Control¶

class Control¶

Subclassed by qamlib::ValueControl

Public Functions

inline Control(v4l2_query_ext_ctrl *query)¶

virtual ~Control() = default¶

virtual std::string to_string() const¶

virtual json to_json() const¶

Public Members

uint32_t id¶

std::string name¶

uint32_t type¶

ControlFlags flags¶

uint32_t elem_size¶

uint32_t elems¶

std::vector<uint32_t> dimensions¶

ValueControl¶

class ValueControl : public qamlib::Control ¶

Subclassed by qamlib::IntegerMenuControl, qamlib::MenuControl

Public Functions

inline ValueControl(v4l2_query_ext_ctrl *query)¶

virtual std::string to_string() const override¶

virtual json to_json() const override¶

Public Members

int64_t min¶

int64_t max¶

int64_t default_value¶

uint64_t step¶

MenuControl¶

class MenuControl : public qamlib::ValueControl ¶

Public Functions

inline MenuControl(v4l2_query_ext_ctrl *query, std::map<uint32_t, std::string> items)¶

virtual std::string to_string() const override¶

virtual json to_json() const override¶

Public Members

std::map<uint32_t, std::string> items¶

IntegerMenuControl¶

class IntegerMenuControl : public qamlib::ValueControl ¶

Public Functions

inline IntegerMenuControl(v4l2_query_ext_ctrl *query, std::map<uint32_t, int64_t> items)¶

virtual std::string to_string() const override¶

virtual json to_json() const override¶

Public Members

std::map<uint32_t, int64_t> items¶

ControlFlags¶

class ControlFlags¶

Public Functions

inline ControlFlags(uint32_t flags)¶

flag_function(disabled, V4L2_CTRL_FLAG_DISABLED)¶

flag_function(grabbed, V4L2_CTRL_FLAG_GRABBED)¶

flag_function(read_only, V4L2_CTRL_FLAG_READ_ONLY)¶

flag_function(update, V4L2_CTRL_FLAG_UPDATE)¶

flag_function(inactive, V4L2_CTRL_FLAG_INACTIVE)¶

flag_function(slider, V4L2_CTRL_FLAG_SLIDER)¶

flag_function(write_only, V4L2_CTRL_FLAG_WRITE_ONLY)¶

flag_function(is_volatile, V4L2_CTRL_FLAG_VOLATILE)¶

flag_function(has_payload, V4L2_CTRL_FLAG_HAS_PAYLOAD)¶

flag_function(execute_on_write, V4L2_CTRL_FLAG_EXECUTE_ON_WRITE)¶

flag_function(modify_layout, V4L2_CTRL_FLAG_MODIFY_LAYOUT)¶

flag_function(dynamic_array, V4L2_CTRL_FLAG_DYNAMIC_ARRAY)¶

std::string to_string() const¶

json to_json() const¶

Public Members

uint32_t flags¶

ControlValue classes¶

IntegerControlValue¶

class IntegerControlValue : public qamlib::ControlValue¶

Public Functions

inline IntegerControlValue(uint32_t type)¶: Internal qamlib function not to be used otherwise

inline IntegerControlValue(int64_t value)¶

inline IntegerControlValue(int32_t value)¶

int64_t get_value() const¶

virtual void check_value(std::shared_ptr<Control> ctrl) override¶: Internal qamlib function not to be used otherwise

virtual void ready_control(v4l2_ext_control &ctrl) override¶: Internal qamlib function not to be used otherwise

virtual void update_value(v4l2_ext_control &ctrl) override¶: Internal qamlib function not to be used otherwise

virtual std::string to_string() const override¶

virtual json to_json() const override¶

StringControlValue¶

class StringControlValue : public qamlib::ControlValue¶

Public Functions

inline StringControlValue(uint32_t max_size)¶: Internal qamlib function not to be used otherwise

inline StringControlValue(std::string &val)¶

virtual void check_value(std::shared_ptr<Control> ctrl) override¶: Internal qamlib function not to be used otherwise

virtual void ready_control(v4l2_ext_control &ctrl) override¶: Internal qamlib function not to be used otherwise

inline ~StringControlValue() override¶

virtual std::string to_string() const override¶

virtual json to_json() const override¶

ArrayControlValue¶

class ArrayControlValue : public qamlib::ControlValue¶

Public Functions

inline ArrayControlValue(uint32_t elements, uint32_t element_size, std::vector<uint32_t> dims, bool sign = false)¶

inline ArrayControlValue(cv::Mat array)¶

cv::Mat get_array() const¶

virtual void check_value(std::shared_ptr<Control> ctrl) override¶: Internal qamlib function not to be used otherwise

virtual void ready_control(v4l2_ext_control &ctrl) override¶: Internal qamlib function not to be used otherwise

inline ~ArrayControlValue() override¶

virtual std::string to_string() const override¶

virtual json to_json() const override¶

Formats¶

ImageFormat¶

class ImageFormat¶

Public Functions

inline ImageFormat(struct v4l2_fmtdesc *fmt)¶

std::string to_string() const¶

json to_json() const¶

Public Members

uint32_t index¶

ImageFormatFlags flags¶

std::string description¶

PixelFormat pixelformat¶

ImageFormatFlags¶

class ImageFormatFlags¶

Public Functions

inline ImageFormatFlags(uint32_t flags)¶

flag_function(compressed, V4L2_FMT_FLAG_COMPRESSED)¶

flag_function(emulated, V4L2_FMT_FLAG_EMULATED)¶

flag_function(continuous_bytestream, V4L2_FMT_FLAG_CONTINUOUS_BYTESTREAM)¶

flag_function(dyn_resolution, V4L2_FMT_FLAG_DYN_RESOLUTION)¶

flag_function(enc_cap_frame_interval, V4L2_FMT_FLAG_ENC_CAP_FRAME_INTERVAL)¶

flag_function(csc_colorspace, V4L2_FMT_FLAG_CSC_COLORSPACE)¶

flag_function(csc_xfer_func, V4L2_FMT_FLAG_CSC_XFER_FUNC)¶

flag_function(csc_ycbcr_enc, V4L2_FMT_FLAG_CSC_YCBCR_ENC)¶

flag_function(csc_hsv_enc, V4L2_FMT_FLAG_CSC_HSV_ENC)¶

flag_function(csc_quantization, V4L2_FMT_FLAG_CSC_QUANTIZATION)¶

std::string to_string() const¶

json to_json() const¶

Public Members

uint32_t flags¶

Format¶

class Format¶

Subclassed by qamlib::SinglePlaneFormat

Public Functions

inline Format(v4l2_buf_type type)¶

virtual ~Format() = default¶

Public Members

v4l2_buf_type type¶

SinglePlaneFormat¶

class SinglePlaneFormat : public qamlib::Format ¶

Public Functions

inline SinglePlaneFormat(struct v4l2_pix_format *fmt, v4l2_buf_type type)¶

std::string to_string() const¶

json to_json() const¶

Public Members

uint32_t width¶

uint32_t height¶

PixelFormat pixelformat¶

v4l2_field field¶

uint32_t bytesperline¶

uint32_t sizeimage¶

v4l2_colorspace colorspace¶

bool priv¶

PixelFormatFlags flags¶

v4l2_quantization quantization¶

v4l2_xfer_func xfer_func¶

PixelFormat¶

class PixelFormat¶

Public Functions

inline PixelFormat(uint32_t code)¶

inline PixelFormat(const std::string &fourcc, bool big_endian)¶

inline PixelFormat(const std::string &fourcc)¶

std::string get_fourcc() const¶

void set_fourcc(std::string &new_name)¶

uint32_t get_code() const¶

std::string to_string() const¶

Public Members

bool big_endian = false¶

PixelFormatFlags¶

class PixelFormatFlags¶

Public Functions

inline PixelFormatFlags(uint32_t flags)¶

flag_function(premul_alpha, V4L2_PIX_FMT_FLAG_PREMUL_ALPHA)¶

flag_function(set_csc, V4L2_PIX_FMT_FLAG_SET_CSC)¶

std::string to_string() const¶

json to_json() const¶

Public Members

uint32_t flags¶

Framerates¶

FrameRate¶

class FrameRate¶

Subclassed by qamlib::ContinuousFrameRate, qamlib::DiscreteFrameRate

Public Functions

virtual ~FrameRate() = default¶

Public Members

v4l2_frmivaltypes type¶

DiscreteFrameRate¶

class DiscreteFrameRate : public qamlib::FrameRate ¶

Public Functions

inline DiscreteFrameRate(std::vector<double> values)¶

std::string to_string() const¶

json to_json() const¶

Public Members

std::vector<double> values¶

ContinuousFrameRate¶

class ContinuousFrameRate : public qamlib::FrameRate ¶

Subclassed by qamlib::StepwiseFrameRate

Public Functions

inline ContinuousFrameRate(double min, double max)¶

std::string to_string() const¶

json to_json() const¶

Public Members

double min¶

double max¶

StepwiseFrameRate¶

class StepwiseFrameRate : public qamlib::ContinuousFrameRate ¶

Public Functions

inline StepwiseFrameRate(double min, double max, double step)¶

std::string to_string() const¶

json to_json() const¶

Public Members

double step¶

Events¶

BaseEvent¶

class BaseEvent¶

Subclassed by qamlib::ControlEvent, qamlib::SourceEvent

Public Functions

inline BaseEvent(v4l2_event &event)¶

virtual ~BaseEvent() = default¶

std::string to_string() const¶

Public Members

EventType type¶

uint32_t pending¶

uint32_t sequence¶

double timestamp¶

uint32_t id¶

ControlEvent¶

class ControlEvent : public qamlib::BaseEvent ¶

Public Functions

inline ControlEvent(v4l2_event &event)¶

std::string to_string() const¶

Public Members

ControlChangesFlags changes¶

uint32_t control_type¶

int64_t value¶

ControlFlags flags¶

int min¶

int max¶

int step¶

int default_value¶

EventType¶

enum qamlib::EventType¶

Values:

enumerator ALL¶

enumerator VSYNC¶

enumerator EOS¶

enumerator CTRL¶

enumerator FRAME_SYNC¶

enumerator SOURCE_CHANGE¶

enumerator MOTION_DET¶

ControlChangesFlags¶

class ControlChangesFlags¶

Public Functions

inline ControlChangesFlags(uint32_t flags)¶

flag_function(value, V4L2_EVENT_CTRL_CH_VALUE)¶

flag_function(ch_flags, V4L2_EVENT_CTRL_CH_FLAGS)¶

flag_function(range, V4L2_EVENT_CTRL_CH_RANGE)¶

std::string to_string() const¶

Misc¶

FrameMetadata¶

class FrameMetadata¶

Metadata for a frame. time is in machine clock with clock specifying which clock is used sequence is the framenumber since the stream was started

Public Functions

std::string to_string()¶: Function to “pretty-print” the FrameMetadata struct

Public Members

double time¶

clockid_t clock¶

uint32_t sequence¶

Rectangle¶

class Rectangle¶

Public Functions

inline Rectangle()¶

inline Rectangle(int left, int top, uint32_t width, uint32_t height)¶

inline std::string to_string()¶

inline std::vector<int> as_vector()¶

inline bool operator==(const Rectangle &rhs) const¶

inline bool operator!=(const Rectangle &rhs) const¶

Public Members

int left = 0¶

int top = 0¶

uint32_t width = 0¶

uint32_t height = 0¶

Exceptions¶

V4L2Exception¶

class V4L2Exception : public std::exception¶

Subclassed by qamlib::V4L2BusyException

Public Functions

inline V4L2Exception(const std::string &msg, int err_num)¶

inline V4L2Exception(const std::string &msg)¶

inline V4L2Exception(const std::string &name, const std::string &msg)¶

inline const char *what() const noexcept override¶

virtual ~V4L2Exception() = default¶

TimeoutException¶

class TimeoutException : public std::exception¶

Public Functions

inline TimeoutException()¶

inline const char *what() const noexcept override¶

DroppedFrameException¶

class DroppedFrameException : public std::exception¶

Public Functions

inline DroppedFrameException()¶

inline const char *what() const noexcept override¶