A class representing a video channel. More...

#include <video.h>

Inheritance diagram for PVideoChannel:

Collaboration diagram for PVideoChannel:

Public Member Functions
virtual PINDEX	GetGrabWidth ()
	Return the width of the currently selected grabbing device. More...

virtual PINDEX	GetGrabHeight ()
	Return the height of the currently selected grabbing device. More...

virtual PBoolean	Read (void *buf, PINDEX len)
	Low level read from the channel. More...

PBoolean	Write (const void *buf, PINDEX len)
	Low level write to the channel, which is data to be rendered to the local video display device. More...

virtual PBoolean	Write (const void buf, PINDEX len, void mark)
	Low level write to the video channel with marker. More...

virtual PBoolean	Redraw (const void *frame)
	Cause the referenced data to be drawn to the previously defined media. More...

PINDEX	GetRenderWidth ()
	Return the previously specified width. More...

PINDEX	GetRenderHeight ()
	Return the previously specified height. More...

virtual void	SetRenderFrameSize (int width, int height)
	Specify the width and height of the video stream, which is to be rendered onto the previously specified device. More...

virtual void	SetRenderFrameSize (int width, int height, int sarwidth, int sarheight)
	Specify the width and height of the video stream, which is to be rendered onto the previously specified device including sample aspect ratio. More...

virtual void	SetGrabberFrameSize (int width, int height)
	Specifiy the width and height of the video stream, which is to be extracted from the previously specified device. More...

virtual void	AttachVideoPlayer (PVideoOutputDevice *device, PBoolean keepCurrent=true)
	Attach a user specific class for rendering video. More...

virtual void	AttachVideoReader (PVideoInputDevice *device, PBoolean keepCurrent=true)
	Attach a user specific class for acquiring video. More...

virtual PVideoInputDevice *	GetVideoReader ()
	Return a pointer to the class for acquiring video. More...

virtual PVideoOutputDevice *	GetVideoPlayer ()
	Return a pointer to the class for displaying video. More...

virtual PBoolean	IsGrabberOpen ()
	See if the grabber is open. More...

virtual PBoolean	IsRenderOpen ()
	See if the rendering device is open. More...

virtual PBoolean	DisableDecode ()
	Allow the outputdevice decide whether the decoder should ignore decode hence not render any output. More...

PBoolean	DisplayRawData (void *videoBuffer)
	Get data from the attached inputDevice, and display on the attached ouptutDevice. More...

virtual void	CloseVideoReader ()
	Destroy the attached grabber class. More...

virtual void	CloseVideoPlayer ()
	Destroy the attached video display class. More...

void	RestrictAccess ()
	Restrict others from using this video channel. More...

void	EnableAccess ()
	Allow free access to this video channel. More...

PBoolean	ToggleVFlipInput ()
	Toggle the vertical flip state of the video grabber. More...

virtual bool	FlowControl (const void *flowData)
	Flow Control information Pass data to the channel for flowControl determination. More...

virtual PBoolean	Close ()
	Close the channel, shutting down the link to the data source. More...

virtual PString	GetName () const
	Get the platform and I/O channel type name of the channel. More...

PString	GetErrorText () const

Public Member Functions inherited from PChannel
PBoolean	SetErrorValues (Errors errorCode, int osError, ErrorGroup group=LastGeneralError)
	Set error values to those specified. More...

virtual Comparison	Compare (const PObject &obj) const
	Get the relative rank of the two strings. More...

virtual PINDEX	HashFunction () const
	Calculate a hash value for use in sets and dictionaries. More...

virtual P_INT_PTR	GetHandle () const
	Get the integer operating system handle for the channel. More...

FILE *	FDOpen (const char *mode)
	Re-open the device using the stdio library. More...

virtual PChannel *	GetBaseReadChannel () const
	Get the base channel of channel indirection using PIndirectChannel. More...

virtual PChannel *	GetBaseWriteChannel () const
	Get the base channel of channel indirection using PIndirectChannel. More...

virtual bool	CloseBaseReadChannel ()
	Close the base channel of channel indirection using PIndirectChannel. More...

virtual bool	CloseBaseWriteChannel ()
	Close the base channel of channel indirection using PIndirectChannel. More...

void	SetReadTimeout (const PTimeInterval &time)
	Set the timeout for read operations. More...

PTimeInterval	GetReadTimeout () const
	Get the timeout for read operations. More...

virtual PINDEX	GetLastReadCount () const
	Get the number of bytes read by the last Read() call. More...

virtual PINDEX	SetLastReadCount (PINDEX count)

virtual int	ReadChar ()
	Read a single character from the channel. More...

PBoolean	ReadBlock (void *buf, PINDEX len)
	Read len bytes into the buffer from the channel. More...

PString	ReadString (PINDEX len)
	Read `len` character into a string from the channel. More...

void	SetWriteTimeout (const PTimeInterval &time)
	Set the timeout for write operations to complete. More...

PTimeInterval	GetWriteTimeout () const
	Get the timeout for write operations to complete. More...

virtual PBoolean	Write (const void buf, PINDEX len, const void )
	Low level write to the channel with marker. More...

virtual PINDEX	GetLastWriteCount () const
	Get the number of bytes written by the last Write() call. More...

virtual PINDEX	SetLastWriteCount (PINDEX count)

PBoolean	WriteChar (int c)
	Write a single character to the channel. More...

PBoolean	WriteString (const PString &str)
	Write a string to the channel. More...

	~PChannel ()
	Close down the channel. More...

Errors	GetErrorCode (ErrorGroup group=NumErrorGroups) const
	Get normalised error code. More...

int	GetErrorNumber (ErrorGroup group=NumErrorGroups) const
	Get OS errro code. More...

virtual PString	GetErrorText (ErrorGroup group=NumErrorGroups) const
	Get error message description. More...

virtual bool	ReadAsync (AsyncContext &context)
	Begin an asynchronous read from channel. More...

virtual void	OnReadComplete (AsyncContext &context)
	User callback function for when a `ReadAsync()` call has completed or timed out. More...

virtual bool	WriteAsync (AsyncContext &context)
	Begin an asynchronous write from channel. More...

virtual void	OnWriteComplete (AsyncContext &context)
	User callback function for when a WriteAsync() call has completed or timed out. More...

virtual PBoolean	Shutdown (ShutdownValue option)
	Close one or both of the data streams associated with a channel. More...

virtual bool	SetLocalEcho (bool localEcho)
	Set local echo mode. More...

PBoolean	SetBufferSize (PINDEX newSize)
	Set the iostream buffer size for reads and writes. More...

PBoolean	SendCommandString (const PString &command)
	Send a command meta-string. More...

void	AbortCommandString ()
	Abort a command string that is in progress. More...

Public Member Functions inherited from PObject
__inline unsigned	GetTraceContextIdentifier () const
	Get PTRACE context identifier. More...

__inline void	SetTraceContextIdentifier (unsigned id)

__inline void	SetTraceContextIdentifier (const PObject &obj)

__inline void	SetTraceContextIdentifier (const PObject *obj)

__inline void	CopyTraceContextIdentifier (PObject &obj) const

__inline void	CopyTraceContextIdentifier (PObject *obj) const

virtual	~PObject ()

__inline const char *	GetClass () const

__inline bool	IsClass (const char *name) const

__inline const PObject *	PTraceObjectInstance () const

virtual PObject *	Clone () const
	Create a copy of the class on the heap. More...

template<class CLS >
CLS *	CloneAs () const
	As for Clone() but converts to specified type. More...

virtual Comparison	CompareObjectMemoryDirect (const PObject &obj) const
	Determine the byte wise comparison of two objects. More...

bool	operator== (const PObject &obj) const
	Compare the two objects. More...

bool	operator!= (const PObject &obj) const
	Compare the two objects. More...

bool	operator< (const PObject &obj) const
	Compare the two objects. More...

bool	operator> (const PObject &obj) const
	Compare the two objects. More...

bool	operator<= (const PObject &obj) const
	Compare the two objects. More...

bool	operator>= (const PObject &obj) const
	Compare the two objects. More...

virtual void	PrintOn (ostream &strm) const
	Output the contents of the object to the stream. More...

virtual void	ReadFrom (istream &strm)
	Input the contents of the object from the stream. More...

Protected Attributes
Directions	direction

PString	deviceName

PVideoInputDevice *	mpInput
	Specified video device name, eg /dev/video0. More...

PVideoOutputDevice *	mpOutput
	For grabbing video from the camera. More...

PMutex	accessMutex
	For displaying video on the screen. More...

Protected Attributes inherited from PChannel
PTimeInterval	readTimeout
	Timeout for read operations. More...

PTimeInterval	writeTimeout
	Timeout for write operations. More...

atomic< P_INT_PTR >	os_handle
	The operating system file handle return by standard open() function. More...

PThreadLocalStorage< Status >	m_status [NumErrorGroups+1]

PXBlockType	px_lastBlockType

PThread *	px_readThread

PThread *	px_writeThread

PThread *	px_selectThread [3]

PCriticalSection	px_selectMutex [3]

Protected Attributes inherited from PObject
unsigned	m_traceContextIdentifier

Static Protected Attributes
static PMutex	dictMutex

Construction
enum	Directions { Recorder, Player }

	PVideoChannel ()
	Create a video channel. More...

	PVideoChannel (const PString &device, Directions dir)
	Create a video channel. More...

	~PVideoChannel ()

Open functions
PBoolean	Open (const PString &device, Directions dir)
	Open the specified device for playing or recording. More...

PBoolean	IsOpen () const
	return True if one (or both) of the video device class pointers is non NULL. More...

static PStringArray	GetDeviceNames (Directions dir)
	Get all of the names for video devices/drivers that are available on this platform. More...

static PString	GetDefaultDevice (Directions dir)
	Get the name for the default video devices/driver that is on this platform. More...

Additional Inherited Members
Public Types inherited from PChannel
enum	PXBlockType { PXReadBlock, PXWriteBlock, PXAcceptBlock, PXConnectBlock }

enum	Errors { NoError, NotFound, FileExists, DiskFull, AccessDenied, DeviceInUse, BadParameter, NoMemory, NotOpen, Timeout, Interrupted, BufferTooSmall, Miscellaneous, ProtocolFailure, Unavailable, NumNormalisedErrors }
	Normalised error codes. More...

enum	ErrorGroup { LastReadError, LastWriteError, LastGeneralError, NumErrorGroups }
	Error groups. More...

typedef PNotifierTemplate < PChannel::AsyncContext & >	AsyncNotifier

enum	ShutdownValue { ShutdownRead = 0, ShutdownWrite = 1, ShutdownReadAndWrite = 2 }

Public Types inherited from PObject
enum	Comparison { LessThan = -1, EqualTo = 0, GreaterThan = 1 }
	Result of the comparison operation performed by the `Compare()` function. More...

Static Public Member Functions inherited from PChannel
static PString	GetErrorText (Errors lastError, int osError=0)
	Get error message description. More...

Static Public Member Functions inherited from PObject
static __inline void	CopyTraceContextIdentifier (PObject &to, const PObject &from)

static __inline void	CopyTraceContextIdentifier (PObject &to, const PObject *from)

static __inline void	CopyTraceContextIdentifier (PObject *to, const PObject &from)

static __inline void	CopyTraceContextIdentifier (PObject to, const PObject from)

static __inline const char *	Class ()

static __inline const PObject *	PTraceObjectInstance (const char *)

static __inline const PObject *	PTraceObjectInstance (const PObject *obj)

template<typename T >
static Comparison	Compare2 (T v1, T v2)
	Compare two types, returning Comparison type. More...

static Comparison	InternalCompareObjectMemoryDirect (const PObject obj1, const PObject obj2, PINDEX size)
	Internal function caled from CompareObjectMemoryDirect() More...

Protected Member Functions inherited from PChannel
	PChannel (const PChannel &)

PChannel &	operator= (const PChannel &)

virtual PBoolean	ConvertOSError (P_INT_PTR libcReturnValue, ErrorGroup group=LastGeneralError)
	Convert an operating system error into platform independent error. More...

int	ReadCharWithTimeout (PTimeInterval &timeout)
	Read a character with specified timeout. More...

PBoolean	ReceiveCommandString (int nextChar, const PString &reply, PINDEX &pos, PINDEX start)

bool	CheckNotOpen ()

virtual int	os_errno () const

PBoolean	PXSetIOBlock (PXBlockType type, const PTimeInterval &timeout)

P_INT_PTR	GetOSHandleAsInt () const

int	PXClose ()

	PDECLARE_MUTEX (px_threadMutex)

	PDECLARE_MUTEX (px_writeMutex)

	PChannel ()
	Create the channel. More...

Protected Member Functions inherited from PObject
	PObject ()
	Constructor for PObject, made protected so cannot ever create one on its own. More...

Detailed Description

A class representing a video channel.

This class is provided mainly for the playback or recording of video on the system.

Note that this video channel is implicitly a series of frames in YUV411P format. No conversion is performed on data to/from the channel.

Member Enumeration Documentation

enum PVideoChannel::Directions

Enumerator
Recorder
Player

Constructor & Destructor Documentation

PVideoChannel::PVideoChannel ( )

Create a video channel.

PVideoChannel::PVideoChannel	(	const PString &	device,
		Directions	dir
	)

Create a video channel.

Create a reference to the video drivers for the platform.

Parameters

device	Name of video driver/device
dir	Video I/O direction

PVideoChannel::~PVideoChannel ( )

Member Function Documentation

virtual void PVideoChannel::AttachVideoPlayer	(	PVideoOutputDevice *	device,
		PBoolean	keepCurrent = `true`
	)

virtual

Attach a user specific class for rendering video.

If keepCurrent is true, an abort is caused when the program attempts to attach a new player when there is already a video player attached.

If keepCurrent is false, the existing video player is deleted before attaching the new player.

virtual void PVideoChannel::AttachVideoReader	(	PVideoInputDevice *	device,
		PBoolean	keepCurrent = `true`
	)

virtual

Attach a user specific class for acquiring video.

If keepCurrent is true, an abort is caused when the program attempts to attach a new reader when there is already a video reader attached.

If keepCurrent is false, the existing video reader is deleted before attaching the new reader.

virtual PBoolean PVideoChannel::Close ( )

virtual

Close the channel, shutting down the link to the data source.

Returns: true if the channel successfully closed.

Reimplemented from PChannel.

virtual void PVideoChannel::CloseVideoPlayer ( )

virtual

Destroy the attached video display class.

virtual void PVideoChannel::CloseVideoReader ( )

virtual

Destroy the attached grabber class.

virtual PBoolean PVideoChannel::DisableDecode ( )

virtual

Allow the outputdevice decide whether the decoder should ignore decode hence not render any output.

This does not mean the video channel is closed just to not decode and render any frames.

PBoolean PVideoChannel::DisplayRawData ( void * videoBuffer )

Get data from the attached inputDevice, and display on the attached ouptutDevice.

void PVideoChannel::EnableAccess ( )

Allow free access to this video channel.

virtual bool PVideoChannel::FlowControl ( const void * flowData )

virtual

Flow Control information Pass data to the channel for flowControl determination.

Reimplemented from PChannel.

static PString PVideoChannel::GetDefaultDevice ( Directions dir )

static

Get the name for the default video devices/driver that is on this platform.

Note that a named device may not necessarily do both playing and recording so the arrays returned with the dir parameter in each value is not necessarily the same.

Returns: A platform dependent string for the video player/recorder.

static PStringArray PVideoChannel::GetDeviceNames ( Directions dir )

static

Get all of the names for video devices/drivers that are available on this platform.

Note that a named device may not necessarily do both playing and recording so the arrays returned with the dir parameter in each value is not necessarily the same.

Returns: An array of platform dependent strings for each video player/recorder.

Parameters

dir	Video I/O direction

PString PVideoChannel::GetErrorText ( ) const

virtual PINDEX PVideoChannel::GetGrabHeight ( )

virtual

Return the height of the currently selected grabbing device.

virtual PINDEX PVideoChannel::GetGrabWidth ( )

virtual

Return the width of the currently selected grabbing device.

virtual PString PVideoChannel::GetName ( ) const

virtual

Get the platform and I/O channel type name of the channel.

For example, it would return the filename in PFile type channels.

Returns: the name of the channel.

Implements PChannel.

PINDEX PVideoChannel::GetRenderHeight ( )

Return the previously specified height.

PINDEX PVideoChannel::GetRenderWidth ( )

Return the previously specified width.

virtual PVideoOutputDevice* PVideoChannel::GetVideoPlayer ( )

virtual

Return a pointer to the class for displaying video.

virtual PVideoInputDevice* PVideoChannel::GetVideoReader ( )

virtual

Return a pointer to the class for acquiring video.

virtual PBoolean PVideoChannel::IsGrabberOpen ( )

virtual

See if the grabber is open.

PBoolean PVideoChannel::IsOpen ( ) const

virtual

return True if one (or both) of the video device class pointers is non NULL.

If either pointer is non NULL, then a device is ready to be written to, which indicates this channel is open.

Reimplemented from PChannel.

virtual PBoolean PVideoChannel::IsRenderOpen ( )

virtual

See if the rendering device is open.

PBoolean PVideoChannel::Open	(	const PString &	device,
		Directions	dir
	)

Open the specified device for playing or recording.

The device name is platform specific and is as returned in the GetDevices() function.

Returns: true if the video device is valid for playing/recording.

Parameters

device	Name of video driver/device
dir	Video I/O direction

virtual PBoolean PVideoChannel::Read	(	void *	buf,
		PINDEX	len
	)

virtual

Low level read from the channel.

This function may block until the requested number of characters were read or the read timeout was reached. The GetLastReadCount() function returns the actual number of bytes read.

The GetErrorCode() function should be consulted after Read() returns false to determine what caused the failure.

Returns: true indicates that at least one character was read from the channel. false means no bytes were read due to timeout or some other I/O error.

Reimplemented from PChannel.

virtual PBoolean PVideoChannel::Redraw ( const void * frame )

virtual

Cause the referenced data to be drawn to the previously defined media.

void PVideoChannel::RestrictAccess ( )

Restrict others from using this video channel.

virtual void PVideoChannel::SetGrabberFrameSize	(	int	width,
		int	height
	)

virtual

Specifiy the width and height of the video stream, which is to be extracted from the previously specified device.

virtual void PVideoChannel::SetRenderFrameSize	(	int	width,
		int	height
	)

virtual

Specify the width and height of the video stream, which is to be rendered onto the previously specified device.

virtual void PVideoChannel::SetRenderFrameSize	(	int	width,
		int	height,
		int	sarwidth,
		int	sarheight
	)

virtual

Specify the width and height of the video stream, which is to be rendered onto the previously specified device including sample aspect ratio.

PBoolean PVideoChannel::ToggleVFlipInput ( )

Toggle the vertical flip state of the video grabber.

PBoolean PVideoChannel::Write	(	const void *	buf,
		PINDEX	len
	)

virtual

Low level write to the channel, which is data to be rendered to the local video display device.

Reimplemented from PChannel.

virtual PBoolean PVideoChannel::Write	(	const void *	buf,
		PINDEX	len,
		void *	mark
	)

virtual

Low level write to the video channel with marker.

Parameters

buf	Pointer to a block of memory to write.
len	Number of bytes to write.
mark	Unique Marker to identify write

Member Data Documentation

PMutex PVideoChannel::accessMutex

protected

For displaying video on the screen.

PString PVideoChannel::deviceName

protected

PMutex PVideoChannel::dictMutex

staticprotected

Directions PVideoChannel::direction

protected

PVideoInputDevice* PVideoChannel::mpInput

protected

Specified video device name, eg /dev/video0.

PVideoOutputDevice* PVideoChannel::mpOutput

protected

For grabbing video from the camera.

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

video.h

Public Member Functions

Protected Attributes

Static Protected Attributes

Construction

Open functions

Additional Inherited Members

Detailed Description

Member Enumeration Documentation

Constructor & Destructor Documentation

Member Function Documentation

Member Data Documentation