au.edu.jcu.v4l4j

Class YVUFrameGrabber

java.lang.Object

au.edu.jcu.v4l4j.YVUFrameGrabber

All Implemented Interfaces:

FrameGrabber

public class YVUFrameGrabber
extends Object

Objects of this class are used to retrieve YVU420-encoded frames from a VideoDevice. A YVU420 frame grabber can only be created if the associated video device can produce images in a format v4l4j knows how to encode in YVU420. The VideoDevice.supportYVUConversion() method can be used to find out whether a video device can have its images YVU420-encoded by v4l4j, ie if a YVU420 frame grabber can be instantiated. YVUFrameGrabber objects are not instantiated directly. Instead, the VideoDevice.getYVUFrameGrabber(int, int, int, int) or VideoDevice.getYVUFrameGrabber(int, int, int, int, ImageFormat) method must be called on the associated VideoDevice. YVU frame grabbers implement the FrameGrabber interface which provides methods to handle video capture. See its documentation for more information.

Author:

gilles

See Also:

{@link FrameGrabber}

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
protected static class	AbstractGrabber.State

Field Summary

Fields

Modifier and Type	Field and Description
protected static int	BGR24_GRABBER
protected DeviceInfo	dInfo
protected int	format
protected static int	JPEG_GRABBER
protected int	nbV4LBuffers
protected long	object
protected static int	RAW_GRABBER
protected static int	RGB24_GRABBER
protected AbstractGrabber.State	state
protected Vector<au.edu.jcu.v4l4j.BaseVideoFrame>	videoFrames
protected static int	YUV_GRABBER
protected static int	YVU_GRABBER

Method Summary

Modifier and Type	Method and Description
protected void	createBuffers(int bufferSize) This abstract method is called when init() succeeds and is responsible for populating the videoFrames member (vector of nbV4LBuffers BaseVideoFrames).
boolean	equals(Object obj)
int	getChannel() This method returns the video channel used to capture frames.
FrameInterval.DiscreteInterval	getFrameInterval() This method returns the current frame interval used for capture.
int	getHeight() This method returns the actual height of captured frames.
ImageFormat	getImageFormat() This method returns the native image format used by this FrameGrabber.
int	getNumberOfRecycledVideoFrames() This method returns the number of recycled video frames, ie.
int	getNumberOfVideoFrames() This method returns the number of buffers v4l4j has negotiated with the driver.
int	getStandard() This method returns the actual video standard: V4L4JConstants.STANDARD_NTSC, V4L4JConstants.STANDARD_PAL , V4L4JConstants.STANDARD_SECAM or V4L4JConstants.STANDARD_WEBCAM
Tuner	getTuner() This method returns the Tuner associated with the input of this FrameGrabber, or throws a NoTunerException if there is none.
int	getVideoInput() This method retrieves the current video input channel number.
int	getVideoStandard() This method retrieves the current video standard used by the current video input.
int	getWidth() This method returns the actual width of captured frames.
int	hashCode()
void	setCaptureCallback(CaptureCallback callback) setCaptureCallback sets the CaptureCallback object which will be notified by this grabber as soon as new frames become available. This method cannot be called while the capture is active, ie.
void	setFrameInterval(int num, int denom) This method sets the frame interval used for capture.
protected void	setQuality(long o, int i) This method sets a new value for the JPEG quality
void	setVideoInputNStandard(int input, int standard) This method adjusts the current video input number and video standard.
void	startCapture() This method starts the capture.
void	stopCapture() This method stops the capture, and recycles all @link VideoFrames.

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, toString, wait, wait, wait

Field Detail

RAW_GRABBER

protected static final int RAW_GRABBER

See Also:

Constant Field Values

JPEG_GRABBER

protected static final int JPEG_GRABBER

See Also:

Constant Field Values

RGB24_GRABBER

protected static final int RGB24_GRABBER

See Also:

Constant Field Values

BGR24_GRABBER

protected static final int BGR24_GRABBER

See Also:

Constant Field Values

YUV_GRABBER

protected static final int YUV_GRABBER

See Also:

Constant Field Values

YVU_GRABBER

protected static final int YVU_GRABBER

See Also:

Constant Field Values

dInfo

protected DeviceInfo dInfo

nbV4LBuffers

protected int nbV4LBuffers

videoFrames

protected Vector<au.edu.jcu.v4l4j.BaseVideoFrame> videoFrames

state

protected AbstractGrabber.State state

format

protected int format

object

protected long object

Method Detail

getImageFormat

public ImageFormat getImageFormat()

This method returns the native image format used by this FrameGrabber. The returned format specifies the image format the capture uses, ie the one images are retrieved from the device BEFORE YVU conversion.

Returns:

the native image format used by this FrameGrabber.

Throws:

StateException - if this FrameGrabber has been already released, and therefore must not be used anymore.

createBuffers

protected void createBuffers(int bufferSize)

This abstract method is called when init() succeeds and is responsible for populating the videoFrames member (vector of nbV4LBuffers BaseVideoFrames).

Parameters:

bufferSize - the size of each buffer

setQuality

protected void setQuality(long o,
                          int i)

This method sets a new value for the JPEG quality

Parameters:

o - the struct v4l4_device

i - the new value

Throws:

V4L4JException - if the JPEG quality is disabled because of the type of this frame grabber (not JPEG_GRABBER).

getNumberOfVideoFrames

public int getNumberOfVideoFrames()

Description copied from interface: FrameGrabber

This method returns the number of buffers v4l4j has negotiated with the driver. The driver stores captured frames in these buffers and returns them to v4l4j. A VideoFrame represents (and encapsulates) one of these buffers. Hence, this number is an indication of how many video frames can be delivered by v4l4j to your application before the capture blocks until a buffer is returned to the driver. Practically speaking, this number specifies how many times v4l4j can call CaptureCallback.nextFrame(VideoFrame frame) and block waiting for one of the previous frames to be recycled through VideoFrame.recycle().
You can specify how many buffers the driver should use by setting the v4l4j.num_driver_buffers property to an integer value before creating a frame grabber object. The number you specify is only an indication, and the driver can decide to allocate a different number of buffers. Before setting this number, make sure you fully understand the implications of doing this.

Specified by:

getNumberOfVideoFrames in interface FrameGrabber

Returns:

the number of frame buffers used to retrieve frames from the driver

getNumberOfRecycledVideoFrames

public int getNumberOfRecycledVideoFrames()

Description copied from interface: FrameGrabber

This method returns the number of recycled video frames, ie. the number of video frames are currently available to v4l4j (and the driver) to store new incoming frames. This number indicates how many more frames can be captured by v4l4j before the capture stops until you recycle one of the previous frame that was delivered to your application by calling VideoFrame.recycle().

Specified by:

getNumberOfRecycledVideoFrames in interface FrameGrabber

Returns:

the number of video frames currently recycled.

See Also:

FrameGrabber.getNumberOfVideoFrames()

setFrameInterval

public void setFrameInterval(int num,
                             int denom)
                      throws InvalidValue

Description copied from interface: FrameGrabber

This method sets the frame interval used for capture. The frame interval defined the lapse of time (in second) between two captured frames and is the inverse of the frame rate. It may or may not be supported by the underlying hardware/driver. If not supported, calling this method throws a UnsupportedMethod exception. This method will throw an InvalidValue exception if the given frame interval value is not supported. As a guide, you can check the ResolutionInfo objects associated with the video device to find out whether frame intervals are at all supported, and if they are, what values (or range of values) are accepted. ResolutionInfo objects can be obtained for each ImageFormat. See the ImageFormat and ResolutionInfo documentation for more information.

Specified by:

setFrameInterval in interface FrameGrabber

Parameters:

num - the numerator of the frame interval to be set

denom - the denominator of the frame interval to be set

Throws:

InvalidValue - if the given frame interval value is invalid.

getFrameInterval

public FrameInterval.DiscreteInterval getFrameInterval()

Description copied from interface: FrameGrabber

This method returns the current frame interval used for capture. It may or may not be supported by the underlying hardware/driver. If not supported, calling this method throws a UnsupportedMethod exception.

Specified by:

getFrameInterval in interface FrameGrabber

setVideoInputNStandard

public void setVideoInputNStandard(int input,
                                   int standard)
                            throws VideoStandardException,
                                   CaptureChannelException

Description copied from interface: FrameGrabber

This method adjusts the current video input number and video standard.

Specified by:

setVideoInputNStandard in interface FrameGrabber

Throws:

VideoStandardException - if the chosen video standard is not supported

CaptureChannelException - if the given channel number value is not valid

getVideoInput

public int getVideoInput()

Description copied from interface: FrameGrabber

This method retrieves the current video input channel number.

Specified by:

getVideoInput in interface FrameGrabber

Returns:

the current input number

getVideoStandard

public int getVideoStandard()

Description copied from interface: FrameGrabber

This method retrieves the current video standard used by the current video input.

Specified by:

getVideoStandard in interface FrameGrabber

Returns:

the current standard

getTuner

public final Tuner getTuner()
                     throws NoTunerException

Description copied from interface: FrameGrabber

This method returns the Tuner associated with the input of this FrameGrabber, or throws a NoTunerException if there is none.

Specified by:

getTuner in interface FrameGrabber

Returns:

the Tuner object associated with the chosen input.

Throws:

NoTunerException - if the selected input does not have a tuner

setCaptureCallback

public final void setCaptureCallback(CaptureCallback callback)

Description copied from interface: FrameGrabber

setCaptureCallback sets the CaptureCallback object which will be notified by this grabber as soon as new frames become available.
This method cannot be called while the capture is active, ie. in between a call to FrameGrabber.startCapture() and FrameGrabber.stopCapture().

Specified by:

setCaptureCallback in interface FrameGrabber

Parameters:

callback - an object implementing the CaptureCallback interface which will receive new frames and capture exceptions.

startCapture

public final void startCapture()
                        throws V4L4JException

Description copied from interface: FrameGrabber

This method starts the capture. Frames will be delivered to the provided CaptureCallback object.

Specified by:

startCapture in interface FrameGrabber

Throws:

V4L4JException - if no valid CaptureCallback object was provided (call FrameGrabber.setCaptureCallback(CaptureCallback callback) OR if the capture cannot be started

stopCapture

public final void stopCapture()

Description copied from interface: FrameGrabber

This method stops the capture, and recycles all @link VideoFrames.

Specified by:

stopCapture in interface FrameGrabber

getHeight

public final int getHeight()

Description copied from interface: FrameGrabber

This method returns the actual height of captured frames.

Specified by:

getHeight in interface FrameGrabber

Returns:

the height

getWidth

public final int getWidth()

Description copied from interface: FrameGrabber

This method returns the actual width of captured frames.

Specified by:

getWidth in interface FrameGrabber

Returns:

the width

getChannel

public final int getChannel()

Description copied from interface: FrameGrabber

This method returns the video channel used to capture frames.

Specified by:

getChannel in interface FrameGrabber

Returns:

the channel

getStandard

public final int getStandard()

Description copied from interface: FrameGrabber

This method returns the actual video standard: V4L4JConstants.STANDARD_NTSC, V4L4JConstants.STANDARD_PAL , V4L4JConstants.STANDARD_SECAM or V4L4JConstants.STANDARD_WEBCAM

Specified by:

getStandard in interface FrameGrabber

Returns:

the video standard

hashCode

public int hashCode()

Overrides:

hashCode in class Object

equals

public boolean equals(Object obj)

Overrides:

equals in class Object