SystemV4L2 Class Reference

A class containing mvV4L2 specific settings to control the overall behaviour of the driver(Device specific interface layout only). More...

#include <mvIMPACT_acquire.h>

Inheritance diagram for SystemV4L2:

Public Member Functions
HOBJ	hObj (void) const
	Returns a unique identifier for the component collection referenced by this object.
const ComponentCollection &	restoreDefault (void) const
	Restores the default for every component of this collection.
	SystemV4L2 (Device *pDev)
	Constructs a new mvIMPACT::acquire::SystemV4L2 object.

Public Attributes
PropertyI	acquisitionIdleTimeMax_ms
	An integer property defining the maximum time in ms the driver waits for new requests being queued until streaming by the device will automatically be stopped.
PropertyIAcquisitionMode	acquisitionMode
	An enumerated integer property defining the acquisition mode of the device.
PropertyI	balance
	If V4L2 device supports audio, this integer property adjusts the audio balance.
PropertyI	bass
	If V4L2 device supports audio, this integer property adjusts the audio bass.
PropertyIBoolean	featurePollingEnable
	An enumerated integer property defining whether features defining a polling time shall be updated automatically or not.
PropertyI	featurePollingInterval_ms
	An integer property defining the polling interval in ms the driver waits for each iteration before running through update loop again.
PropertyIBoolean	genDCParserEnable
	An enumerated integer property which can be used to enable/disable automatic GenICam™ GenDC Container parsing.
PropertyI	imageProcessingMaximumThreadCount
	An integer property influencing the number of parallel threads used by the internal image processing pipeline.
PropertyIImageProcessingMode	imageProcessingMode
	An enumerated integer property influencing the behaviour of the internal image processing pipeline.
PropertyIImageProcessingOptimization	imageProcessingOptimization
	An enumerated integer property influencing the behaviour of the internal image processing algorithms.
PropertyIBoolean	loudness
	If V4L2 device supports audio, this enumerated integer property sets audio loudness on/off.
PropertyI	methodPollingInterval_ms
	An integer property defining the polling interval in ms the driver waits during each iteration before checking a methods execution state again.
PropertyI	methodPollingMaxRetryCount
	An integer property defining the polling interval in ms the driver waits during each iteration before checking a methods execution state again.
PropertyIBoolean	mute
	If V4L2 device supports audio, this enumerated integer property sets audio mute on/off.
PropertyI	requestCount
	An integer property defining the number of requests allocated by the driver.
PropertyI	treble
	If V4L2 device supports audio, this integer property adjusts the audio treble.
PropertyI	volume
	If V4L2 device supports audio, this integer property adjusts the audio volume.

Protected Attributes
HOBJ	m_hRoot

Detailed Description

A class containing mvV4L2 specific settings to control the overall behaviour of the driver(Device specific interface layout only).

Note

UNDER CONSTRUCTION! Subject to change.

This class will only be available if mvIMPACT::acquire::Device::interfaceLayout is set to mvIMPACT::acquire::dilDeviceSpecific before the device is opened.

Constructor & Destructor Documentation

SystemV4L2()

SystemV4L2 ( Device * pDev )

inlineexplicit

Constructs a new mvIMPACT::acquire::SystemV4L2 object.

Parameters

[in]

pDev

A pointer to a mvIMPACT::acquire::Device object obtained from a mvIMPACT::acquire::DeviceManager object.

Member Function Documentation

hObj()

HOBJ hObj ( void ) const

inlineinherited

Returns a unique identifier for the component collection referenced by this object.

This handle will always reference an object of type mvIMPACT::acquire::ComponentList.

Returns

A unique identifier for the component referenced by this object.

restoreDefault()

const ComponentCollection & restoreDefault ( void ) const

inlineinherited

Restores the default for every component of this collection.

Calling this function will restore the default value for every component belonging to this collection.

Note

The caller must have the right to modify the component. Otherwise an exception will be thrown.

Returns

A const reference to the component.

Member Data Documentation

acquisitionIdleTimeMax_ms

PropertyI acquisitionIdleTimeMax_ms

inherited

An integer property defining the maximum time in ms the driver waits for new requests being queued until streaming by the device will automatically be stopped.

This property defines the maximum time in milliseconds the driver waits for new mvIMPACT::acquire::Request objects being queued by calling mvIMPACT::acquire::FunctionInterface::imageRequestSingle once the driver will automatically send an acquisition stop command to a streaming device (such as a GigE Vision or USB3 Vision device) when the driver's request queue has run empty (thus the driver has no more buffers to capture data into).

This property will only be taken into account when mvIMPACT::acquire::Device::acquisitionStartStopBehaviour has been set to mvIMPACT::acquire::assbDefault.

Note

This property will not be available for every device. Right now only devices operated through the GenTL driver package will support this feature.

Since

2.4.1

acquisitionMode

PropertyIAcquisitionMode acquisitionMode

inherited

An enumerated integer property defining the acquisition mode of the device.

Valid values for this property are defined by the enumeration mvIMPACT::acquire::TAcquisitionMode.

balance

PropertyI balance

If V4L2 device supports audio, this integer property adjusts the audio balance.

This property represents a V4L2-audio-control ID.

Note

This property is not supported by every device. Therefore always call the function mvIMPACT::acquire::Component::isValid to check if this property is available or not. If supported, a minimum value, a maximum value and step width will be defined. Thus, invalid values may be tuned after writing to fit within the step size, values too large or too small will raise an exception.

bass

PropertyI bass

If V4L2 device supports audio, this integer property adjusts the audio bass.

This property represents a V4L2-audio-control ID.

Note

This property is not supported by every device. Therefore always call the function mvIMPACT::acquire::Component::isValid to check if this property is available or not. If supported, a minimum value, a maximum value and step width will be defined. Thus, invalid values may be tuned after writing to fit within the step size, values too large or too small will raise an exception.

featurePollingEnable

PropertyIBoolean featurePollingEnable

inherited

An enumerated integer property defining whether features defining a polling time shall be updated automatically or not.

Valid values for this property are defined by the enumeration mvIMPACT::acquire::TBoolean.

See also

mvIMPACT::acquire::SystemSettings::featurePollingInterval_ms

featurePollingInterval_ms

PropertyI featurePollingInterval_ms

inherited

An integer property defining the polling interval in ms the driver waits for each iteration before running through update loop again.

Some features define a so called polling time. This is a recommendation by the device/driver stating that this property might change its value without user interaction act a certain rate (e.g. the device temperature could be one example for a feature with such a behaviour). When mvIMPACT::acquire::SystemSettings::featurePollingEnable is set to mvIMPACT::acquire::bTrue a thread will check every featurePollingInterval_ms if features need to be updated. This will only cause communication with a device for each feature whose polling time has elapsed.

Note

This property will not be available for every device. Right now only devices operated through the GenTL driver package will support this feature.

Since

2.18.3

genDCParserEnable

PropertyIBoolean genDCParserEnable

inherited

An enumerated integer property which can be used to enable/disable automatic GenICam™ GenDC Container parsing.

When working with a GenICam™ compliant device, that transmits data using the GenDC format this property can be used to switch on/off the automatic parsing of the received containers. The default value of this property will be mvIMPACT::acquire::bTrue, so a GenDC container will be parsed upon reception and will be reported as the individual components like described here. This results in slightly more CPU time being consumed which sometimes might not be desirable since the GenDC Containers shall be processed later by another entity of the application or shall just be written to some storage location for off-line processing at a later moment in time. When this property is set to mvIMPACT::acquire::bFalse the data buffer will reported as a raw GenDC Container. mvIMPACT::acquire::Request::payloadType will return mvIMPACT::acquire::ptGenDC then and mvIMPACT::acquire::Request::imagePixelFormat will be mvIMPACT::acquire::ibpfRaw then. mvIMPACT::acquire::Request::imageData and mvIMPACT::acquire::Request::imageSize however can directly be fed into any GenDC capable algorithm.

Note

This property will not be available for every device. Only GenICam™ compliant devices will support this feature. More Information about the GenICam™ GenDC format can be found here: https://www.emva.org/standards-technology/genicam/genicam-downloads/.

Valid values for this property are defined by the enumeration mvIMPACT::acquire::TBoolean.

Since

3.2.0

imageProcessingMaximumThreadCount

PropertyI imageProcessingMaximumThreadCount

inherited

An integer property influencing the number of parallel threads used by the internal image processing pipeline.

This property can be used to control the size of the internal thread pool used for image processing tasks. Using a value higher than the number of physical CPU cores usually has a negative impact on the performance. Use with care!

Note

This property will only be available on some platforms. Always check if this property is available before using it!

See also

mvIMPACT::acquire::SystemSettings::imageProcessingOptimization
mvIMPACT::acquire::SystemSettings::imageProcessingMode
Multithreading

Since

2.41.0

imageProcessingMode

PropertyIImageProcessingMode imageProcessingMode

inherited

An enumerated integer property influencing the behaviour of the internal image processing pipeline.

Valid values for this property are defined by the enumeration mvIMPACT::acquire::TImageProcessingMode.

Note

This property will only be available if mvIMPACT::acquire::Device::userControlledImageProcessingEnable has been set to mvIMPACT::acquire::bTrue before the device is opened.

See also

mvIMPACT::acquire::Device::userControlledImageProcessingEnable
mvIMPACT::acquire::Request::hasProcessingBeenSkipped

Since

2.14.0

imageProcessingOptimization

PropertyIImageProcessingOptimization imageProcessingOptimization

inherited

An enumerated integer property influencing the behaviour of the internal image processing algorithms.

Valid values for this property are defined by the enumeration mvIMPACT::acquire::TImageProcessingOptimization.

Since

2.12.2

loudness

PropertyIBoolean loudness

If V4L2 device supports audio, this enumerated integer property sets audio loudness on/off.

This property represents a boolean-valued V4L2-control ID. Valid values for this property are defined by the enumeration mvIMPACT::acquire::TBoolean.

Note

This property is not supported by every device. Therefore always call the function mvIMPACT::acquire::Component::isValid to check if this property is available or not.

m_hRoot

HOBJ m_hRoot

protectedinherited

methodPollingInterval_ms

PropertyI methodPollingInterval_ms

inherited

An integer property defining the polling interval in ms the driver waits during each iteration before checking a methods execution state again.

When working with a GenICam™ compliant device, GenICam™ method objects need to be checked for their completion status every now and then. This parameter defines how often this shall be done.

Note

This property will not be available for every device. Right now only devices operated through the GenTL driver package will support this feature.

Since

2.18.3

methodPollingMaxRetryCount

PropertyI methodPollingMaxRetryCount

inherited

An integer property defining the polling interval in ms the driver waits during each iteration before checking a methods execution state again.

When working with a GenICam™ compliant device, GenICam™ method objects need to be checked for their completion status every now and then. This parameter defines how often this shall be done at all. A method is checked for completion methodPollingMaxRetryCount * methodPollingInterval_ms at max. Until then either the device starts to inform the driver that it needs more time OR the execution of the method has completed successfully or an error will be generated.

Note

This property will not be available for every device. Right now only devices operated through the GenTL driver package will support this feature.

Since

2.18.3

mute

PropertyIBoolean mute

If V4L2 device supports audio, this enumerated integer property sets audio mute on/off.

This property represents a boolean-valued V4L2-control ID. Valid values for this property are defined by the enumeration mvIMPACT::acquire::TBoolean.

Note

This property is not supported by every device. Therefore always call the function mvIMPACT::acquire::Component::isValid to check if this property is available or not.

requestCount

PropertyI requestCount

inherited

An integer property defining the number of requests allocated by the driver.

Each request object can be used to capture data into. Multiple requests can be processed by a device driver as background tasks.

Setting this property to a value at least allowing a driver to capture data for up to 500ms without user interaction (thus 0.5 times the expected frame rate) is highly recommended. Increasing this value will NOT introduce additional latency to your application. The only drawback will be additional RAM consumption by the driver but applications that do not need to copy the request buffers can even benefit from that as the overall memory fragmentation is likely to go down then. Values smaller than 3 most likely result in undesired behaviour and should be avoided unless absolutely needed.

Note

For performance reasons this value can be increased at any time(only exception: Working with the interface layout mvIMPACT::acquire::dilGenICam while streaming is active) but can only be decreased when no request object is currently locked by the application and no requests has been queued for acquisition. So modifying this value might require the application to call mvIMPACT::acquire::FunctionInterface::imageRequestReset and several calls to mvIMPACT::acquire::Request::unlock before.

There are not too many reasons to modify the default request count suggested by the device driver. Good reasons include:

• a single image is huge compared to the overall system memory(e.g. a single image has 200MB while the system itself only has about 2GB of RAM. Here it might make sense to reduce the number of capture buffers to 1 or 2. Please note that in such a scenario double buffering or live display when one buffer is constantly blocked by the display engine can become a challenge!
• the frame rate is high(larger than 100 frames per second) and no frames shall be lost. Here it might make sense to set the number of capture buffers to something like frame rate divided by 2 to 5 as a rule of thumb.

See also

mvIMPACT::acquire::FunctionInterface::requestCount

Examples

ContinuousCapture.linux.cpp.

treble

PropertyI treble

If V4L2 device supports audio, this integer property adjusts the audio treble.

This property represents a V4L2-audio-control ID.

Note

This property is not supported by every device. Therefore always call the function mvIMPACT::acquire::Component::isValid to check if this property is available or not. If supported, a minimum value, a maximum value and step width will be defined. Thus, invalid values may be tuned after writing to fit within the step size, values too large or too small will raise an exception.

volume

PropertyI volume

If V4L2 device supports audio, this integer property adjusts the audio volume.

This property represents a V4L2-audio-control ID.

Note

This property is not supported by every device. Therefore always call the function mvIMPACT::acquire::Component::isValid to check if this property is available or not. If supported, a minimum value, a maximum value and step width will be defined. Thus, invalid values may be tuned after writing to fit within the step size, values too large or too small will raise an exception.