Abstract class for a generalised sound channel, and an implementation of PSoundChannel for old code that is not plugin-aware. More...

#include <sound.h>

Inheritance diagram for PSoundChannel:

[legend]

Collaboration diagram for PSoundChannel:

[legend]

Public Member Functions
Play functions
virtual PBoolean	Write (const void *buf, PINDEX len)
	Low level write (or play) to the channel. More...

virtual PINDEX	GetLastWriteCount () const
	Get number of bytes written in last Write() operation. More...

virtual PBoolean	PlaySound (const PSound &sound, PBoolean wait=true)
	Play a sound to the open device. More...

virtual PBoolean	PlayFile (const PFilePath &file, PBoolean wait=true)
	Play a sound file to the open device. More...

virtual PBoolean	HasPlayCompleted ()
	Indicate if the sound play begun with PlayBuffer() or PlayFile() has completed. More...

virtual PBoolean	WaitForPlayCompletion ()
	Block calling thread until the sound play begun with PlaySound() or PlayFile() has completed. More...

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

PINDEX	GetLastReadCount () const
	Return number of bytes read in last Read() call. More...

virtual PBoolean	RecordSound (PSound &sound)
	Record into the sound object all of the buffer's of sound data. More...

virtual PBoolean	RecordFile (const PFilePath &file)
	Record into the platform dependent sound file all of the buffer's of sound data. More...

virtual PBoolean	StartRecording ()
	Start filling record buffers. More...

virtual PBoolean	IsRecordBufferFull ()
	Determine if a record buffer has been filled, so that the next Read() call will not block. More...

virtual PBoolean	AreAllRecordBuffersFull ()
	Determine if all of the record buffer allocated has been filled. More...

virtual PBoolean	WaitForRecordBufferFull ()
	Block the thread until a record buffer has been filled, so that the next Read() call will not block. More...

virtual PBoolean	WaitForAllRecordBuffersFull ()
	Block the thread until all of the record buffer allocated has been filled. More...

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...

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

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

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

virtual int	ReadChar ()
	Read a single 8 bit byte 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...

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...

virtual bool	FlowControl (const void *flowData)
	Flow Control information Pass data to the channel for flowControl determination. 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
unsigned	GetTraceContextIdentifier () const
	Get PTRACE context identifier. More...

void	SetTraceContextIdentifier (unsigned id)

void	GetTraceContextIdentifier (PObject &obj)

void	GetTraceContextIdentifier (PObject *obj)

void	SetTraceContextIdentifier (const PObject &obj)

void	SetTraceContextIdentifier (const PObject *obj)

virtual	~PObject ()

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 const char *	GetClass (unsigned ancestor=0) const
	Get the current dynamic type of the object instance. More...

PBoolean	IsClass (const char *cls) const

virtual PBoolean	InternalIsDescendant (const char *clsName) const
	Determine if the dynamic type of the current instance is a descendent of the specified class. More...

__inline const PObject *	PTraceObjectInstance () const

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
PSoundChannel *	m_baseChannel

PReadWriteMutex	m_baseMutex

Directions	activeDirection
	This is the direction that this sound channel is opened for use in. More...

Protected Attributes inherited from PChannel
P_INT_PTR	os_handle
	The operating system file handle return by standard open() function. More...

Errors	lastErrorCode [NumErrorGroups+1]
	The platform independant error code. More...

int	lastErrorNumber [NumErrorGroups+1]
	The operating system error number (eg as returned by errno). More...

PINDEX	lastReadCount
	Number of byte last read by the Read() function. More...

PINDEX	lastWriteCount
	Number of byte last written by the Write() function. More...

PTimeInterval	readTimeout
	Timeout for read operations. More...

PTimeInterval	writeTimeout
	Timeout for write operations. More...

PString	channelName
	Name of channel. More...

PMutex	px_threadMutex

PXBlockType	px_lastBlockType

PThread *	px_readThread

PThread *	px_writeThread

PMutex	px_writeMutex

PThread *	px_selectThread [3]

PMutex	px_selectMutex [3]

Protected Attributes inherited from PObject
unsigned	m_traceContextIdentifier

Construction
enum	Directions { Closed = -1, Recorder, Player }

	PSoundChannel ()
	Create a sound channel. More...

	PSoundChannel (const PString &device, Directions dir, unsigned numChannels=1, unsigned sampleRate=8000, unsigned bitsPerSample=16)
	Create a sound channel. More...

virtual	~PSoundChannel ()

Open functions
virtual PBoolean	Open (const PString &device, Directions dir, unsigned numChannels=1, unsigned sampleRate=8000, unsigned bitsPerSample=16)
	Open the specified device for playing or recording. More...

virtual PBoolean	IsOpen () const
	Test if this instance of PSoundChannel is open. More...

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

virtual P_INT_PTR	GetHandle () const
	Get the OS specific handle for the PSoundChannel. More...

virtual PString	GetName () const
	Get the name of the open channel. More...

Directions	GetDirection () const
	Get the direction of the channel. More...

virtual const char *	GetDirectionText () const

virtual PBoolean	Abort ()
	Abort the background playing/recording of the sound channel. More...

static PStringArray	GetDriverNames (PPluginManager *pluginMgr=NULL)
	Get the list of available sound drivers (plug-ins) More...

static PStringArray	GetDriversDeviceNames (const PString &driverName, Directions direction, PPluginManager *pluginMgr=NULL)
	Get sound devices that correspond to the specified driver name. More...

static PStringArray	GetDeviceNames (const PString &driverName, Directions direction, PPluginManager *pluginMgr=NULL)

static PSoundChannel *	CreateChannel (const PString &driverName, PPluginManager *pluginMgr=NULL)
	Create the sound channel that corresponds to the specified driver name. More...

static PSoundChannel *	CreateChannelByName (const PString &deviceName, Directions direction, PPluginManager *pluginMgr=NULL)

static PSoundChannel *	CreateOpenedChannel (const PString &driverName, const PString &deviceName, Directions direction, unsigned numChannels=1, unsigned sampleRate=8000, unsigned bitsPerSample=16, PPluginManager *pluginMgr=NULL)
	Create an opened sound channel that corresponds to the specified names. More...

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

static PStringArray	GetDeviceNames (Directions direction, PPluginManager *pluginMgr=NULL)
	Get the list of all devices name for the default sound devices/driver that is on this platform. More...

static const char *	GetDirectionText (Directions dir)
	Get text representing the direction of the channel. More...

Channel set up functions
enum	{ MaxVolume = 100 }

virtual PBoolean	SetFormat (unsigned numChannels=1, unsigned sampleRate=8000, unsigned bitsPerSample=16)
	Set the format for play/record. More...

virtual unsigned	GetChannels () const
	Get the number of channels (mono/stereo) in the sound. More...

virtual unsigned	GetSampleRate () const
	Get the sample rate in samples per second. More...

virtual unsigned	GetSampleSize () const
	Get the sample size in bits per sample. More...

virtual PBoolean	SetBuffers (PINDEX size, PINDEX count=2)
	Set the internal buffers for the sound channel I/O. More...

virtual PBoolean	GetBuffers (PINDEX &size, PINDEX &count)
	Get the internal buffers for the sound channel I/O. More...

virtual PBoolean	SetVolume (unsigned volume)
	Set the volume of the play/read process. More...

virtual PBoolean	GetVolume (unsigned &volume)
	Get the volume of the play/read process. More...

virtual bool	SetMute (bool mute)
	Set the mute state of the play/read process. More...

virtual bool	GetMute (bool &mute)
	Get the mute state of the play/read process. 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 }

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

static PBoolean	ConvertOSError (P_INT_PTR libcReturnValue, Errors &lastError, int &osError)
	Convert an operating system error into platform independent error. More...

Static Public Member Functions inherited from PObject
static const char *	Class ()
	Get the name of the class as a C string. More...

static __inline const PObject *	PTraceObjectInstance (const char *)

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

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)

PBoolean	PXSetIOBlock (PXBlockType type, const PTimeInterval &timeout)

P_INT_PTR	GetOSHandleAsInt () const

int	PXClose ()

	PChannel ()
	Create the channel. More...

Friends inherited from PObject

Detailed Description

Abstract class for a generalised sound channel, and an implementation of PSoundChannel for old code that is not plugin-aware.

When instantiated, it selects the first plugin of the base class "PSoundChannel"

As an abstract class, this represents a sound channel. Drivers for real, platform dependent sound hardware will be ancestors of this class and can be found in the plugins section of PTLib.

A sound channel is either playing or recording. If simultaneous playing and recording is desired, two instances of PSoundChannel must be created. It is an error for the same thread to attempt to both read and write audio data to once instance of a PSoundChannel class.

PSoundChannel instances are designed to be reentrant. The actual usage model employed is left to the developer. One model could be where one thread is responsible for construction, setup, opening and read/write operations. After creating and eventually opening the channel this thread is responsible for handling read/writes fast enough to avoid gaps in the generated audio stream.

Remaining operations may beinvoked from other threads. This includes Close() and actually gathering the necessary data to be sent to the device.

Besides the basic I/O task, the Read()/Write(() functions have well defined timing characteristics. When a PSoundChannel instance is used from Opal, the read/write operations are designed to also act as timers so as to nicely space the generated network packets of audio/ sound packets to the speaker.

Read and Writes of audio data to a PSoundChannel are blocking. The length of time required to read/write a block of audio from/to a PSoundChannel instance is equal to the time required for that block of audio to record/play. So for a sound rate of 8khz, 240 samples, it is going to take 30ms to do a read/write.

Since the Read()/Write(() functions have well defined timing characteristics; they are designed to also act as timers in a loop involving data transfers to/from the codecs.

The sound is buffered and the size and number of buffers should be set before playing/recording. Each call to Write() will use one buffer, so care needs to be taken not to use a large number of small writes but tailor the buffers to the size of each write you make.

Similarly for reading, an entire buffer must be read before any of it is available to a Read() call. Note that once a buffer is filled you can read it a byte at a time if desired, but as soon as all the data in the buffer is used, the next read will wait until the entire next buffer is read from the hardware. So again, tailor the number and size of buffers to the application. To avoid being blocked until the buffer fills, you can use the StartRecording() function to initiate the buffer filling, and the IsRecordingBufferFull() function to determine when the Read() function will no longer block.

Note that this sound channel is implicitly a linear PCM channel. No data conversion is performed on data to/from the channel.

Member Enumeration Documentation

anonymous enum

Enumerator
MaxVolume

enum PSoundChannel::Directions

Enumerator
Closed
Recorder
Player

Constructor & Destructor Documentation

PSoundChannel::PSoundChannel ( )

Create a sound channel.

PSoundChannel::PSoundChannel	(	const PString &	device,
		Directions	dir,
		unsigned	numChannels = `1`,
		unsigned	sampleRate = `8000`,
		unsigned	bitsPerSample = `16`
	)

Create a sound channel.

Create a reference to the sound drivers for the platform.

Parameters

device	Name of sound driver/device
dir	Sound I/O direction
numChannels	Number of channels eg mono/stereo
sampleRate	Samples per second
bitsPerSample	Number of bits per sample

virtual PSoundChannel::~PSoundChannel ( )

virtual

Member Function Documentation

virtual PBoolean PSoundChannel::Abort ( )

virtual

Abort the background playing/recording of the sound channel.

There will be a logic assertion if you attempt to Abort a sound channel operation, when the device is currently closed.

Returns: true if the sound has successfully been aborted.

virtual PBoolean PSoundChannel::AreAllRecordBuffersFull ( )

virtual

Determine if all of the record buffer allocated has been filled.

There is an implicit Abort() of the recording if this occurs and recording is stopped. The channel may need to be closed and opened again to start a new recording.

Returns: true if the sound driver has filled a buffer.

virtual PBoolean PSoundChannel::Close ( )

virtual

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

Returns: true if the channel successfully closed.

Reimplemented from PChannel.

static PSoundChannel* PSoundChannel::CreateChannel	(	const PString &	driverName,
		PPluginManager *	pluginMgr = `NULL`
	)

static

Create the sound channel that corresponds to the specified driver name.

Parameters

driverName	Name of driver
pluginMgr	Plug in manager, use default if NULL

static PSoundChannel* PSoundChannel::CreateChannelByName	(	const PString &	deviceName,
		Directions	direction,
		PPluginManager *	pluginMgr = `NULL`
	)

static

Parameters

deviceName	Name of device
direction	Direction for device (record or play)
pluginMgr	Plug in manager, use default if NULL

static PSoundChannel* PSoundChannel::CreateOpenedChannel	(	const PString &	driverName,
		const PString &	deviceName,
		Directions	direction,
		unsigned	numChannels = `1`,
		unsigned	sampleRate = `8000`,
		unsigned	bitsPerSample = `16`,
		PPluginManager *	pluginMgr = `NULL`
	)

static

Create an opened sound channel that corresponds to the specified names.

If the driverName parameter is an empty string or "*" then CreateChannelByName is used with the deviceName parameter which is assumed to be a value returned from GetAllDeviceNames().

Parameters

driverName	Name of driver
deviceName	Name of device
direction	Direction for device (record or play)
numChannels	Number of channels 1=mon, 2=stereo
sampleRate	Sample rate
bitsPerSample	Bits per sample
pluginMgr	Plug in manager, use default if NULL

virtual PBoolean PSoundChannel::GetBuffers	(	PINDEX &	size,
		PINDEX &	count
	)

virtual

Get the internal buffers for the sound channel I/O.

Returns: true if the buffer size were obtained.

virtual unsigned PSoundChannel::GetChannels ( ) const

virtual

Get the number of channels (mono/stereo) in the sound.

static PString PSoundChannel::GetDefaultDevice ( Directions dir )

static

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

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

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

static PStringArray PSoundChannel::GetDeviceNames	(	const PString &	driverName,
		Directions	direction,
		PPluginManager *	pluginMgr = `NULL`
	)

inlinestatic

References GetDriversDeviceNames().

static PStringArray PSoundChannel::GetDeviceNames	(	Directions	direction,
		PPluginManager *	pluginMgr = `NULL`
	)

static

Get the list of all devices name for the default sound 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.

This will return a list of unique device names across all of the available drivers. If two drivers have identical names for devices, then the string returned will be of the form driver+'\t'+device.

Returns: Platform dependent strings for the sound player/recorder.

Parameters

direction	Direction for device (record or play)
pluginMgr	Plug in manager, use default if NULL

Directions PSoundChannel::GetDirection ( ) const

inline

Get the direction of the channel.

References activeDirection.

static const char* PSoundChannel::GetDirectionText ( Directions dir )

static

Get text representing the direction of the channel.

virtual const char* PSoundChannel::GetDirectionText ( ) const

inlinevirtual

References activeDirection.

static PStringArray PSoundChannel::GetDriverNames ( PPluginManager * pluginMgr = NULL )

static

Get the list of available sound drivers (plug-ins)

Parameters

pluginMgr Plug in manager, use default if NULL

static PStringArray PSoundChannel::GetDriversDeviceNames	(	const PString &	driverName,
		Directions	direction,
		PPluginManager *	pluginMgr = `NULL`
	)

static

Get sound devices that correspond to the specified driver name.

If driverName is an empty string or the value "*" then GetAllDeviceNames() is used.

Parameters

driverName	Name of driver
direction	Direction for device (record or play)
pluginMgr	Plug in manager, use default if NULL

Referenced by GetDeviceNames().

virtual P_INT_PTR PSoundChannel::GetHandle ( ) const

virtual

Get the OS specific handle for the PSoundChannel.

Returns: integer value of the handle.

PINDEX PSoundChannel::GetLastReadCount ( ) const

virtual

Return number of bytes read in last Read() call.

Reimplemented from PChannel.

virtual PINDEX PSoundChannel::GetLastWriteCount ( ) const

virtual

Get number of bytes written in last Write() operation.

Reimplemented from PChannel.

virtual bool PSoundChannel::GetMute ( bool & mute )

virtual

Get the mute state of the play/read process.

Returns: true if there were no errors.

Parameters

mute	Variable to receive mute state.

virtual PString PSoundChannel::GetName ( ) const

virtual

Get the name of the open channel.

Reimplemented from PChannel.

virtual unsigned PSoundChannel::GetSampleRate ( ) const

virtual

Get the sample rate in samples per second.

virtual unsigned PSoundChannel::GetSampleSize ( ) const

virtual

Get the sample size in bits per sample.

virtual PBoolean PSoundChannel::GetVolume ( unsigned & volume )

virtual

Get the volume of the play/read process.

The volume range is 0 == muted, 100 == LOUDEST. The volume is a logarithmic scale mapped from the lowest gain possible on the device to the highest gain.

Returns: true if there were no errors.

Parameters

volume Variable to receive volume level.

virtual PBoolean PSoundChannel::HasPlayCompleted ( )

virtual

Indicate if the sound play begun with PlayBuffer() or PlayFile() has completed.

Returns: true if the sound has completed playing.

virtual PBoolean PSoundChannel::IsOpen ( ) const

virtual

Test if this instance of PSoundChannel is open.

Returns: true if this instance is open.

Reimplemented from PChannel.

virtual PBoolean PSoundChannel::IsRecordBufferFull ( )

virtual

Determine if a record buffer has been filled, so that the next Read() call will not block.

Provided that the amount of data read is less than the buffer size.

Returns: true if the sound driver has filled a buffer.

virtual PBoolean PSoundChannel::Open	(	const PString &	device,
		Directions	dir,
		unsigned	numChannels = `1`,
		unsigned	sampleRate = `8000`,
		unsigned	bitsPerSample = `16`
	)

virtual

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 sound device is valid for playing/recording.

Parameters

device	Name of sound driver/device
dir	Sound I/O direction
numChannels	Number of channels eg mono/stereo
sampleRate	Samples per second
bitsPerSample	Number of bits per sample

virtual PBoolean PSoundChannel::PlayFile	(	const PFilePath &	file,
		PBoolean	wait = `true`
	)

virtual

Play a sound file to the open device.

If the wait parameter is true then the function does not return until the file has been played. If false then the sound play is begun asynchronously and the function returns immediately.

Note if the driver is closed of the object destroyed then the sound play is aborted.

Also note that not all possible sounds and sound files are playable by this library. No format conversions between sound object and driver are performed.

Returns: true if the sound is playing or has played.

Parameters

file	Sound file to play.
wait	Flag to play sound synchronously.

virtual PBoolean PSoundChannel::PlaySound	(	const PSound &	sound,
		PBoolean	wait = `true`
	)

virtual

Play a sound to the open device.

If the wait parameter is true then the function does not return until the file has been played. If false then the sound play is begun asynchronously and the function returns immediately.

Note: if the driver is closed while playing the sound, the play operation stops immediately.

Also note that not all possible sounds and sound files are playable by this library. No format conversions between sound object and driver are performed.

Returns: true if the sound is playing or has played.

Parameters

sound	Sound to play.
wait	Flag to play sound synchronously.

virtual PBoolean PSoundChannel::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.

It will generate a logical assertion if you attempt to read from a PSoundChannel that is setup for playing.

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

Parameters

len	Nr of bytes to endeaveour to read from the sound device. If len equals the buffer size set by SetBuffers() it will block for (1000len)/(samplesizesamplerate) ms. Typically, the sample size is 2 bytes. If len == 0, this will return immediately, where the return value is equal to the value of IsOpen().
buf	is a pointer to the empty data area, which will contain the data collected from the sound device. It is an error for this pointer to be NULL. A logical assert will be generated when buf is NULL.

Returns: true indicates that at least one character was read from the channel. false means no bytes were read due to some I/O error, (which includes timeout or some other thread closed the device).

Parameters

buf	Pointer to a block of memory to receive the read bytes.
len	Maximum number of bytes to read into the buffer.

Reimplemented from PChannel.

virtual PBoolean PSoundChannel::RecordFile ( const PFilePath & file )

virtual

Record into the platform dependent sound file all of the buffer's of sound data.

Use the SetBuffers() function to determine how long the recording will be made.

Note that this function will block until all of the data is buffered. If you wish to do this asynchronously, use StartRecording() and AreAllrecordBuffersFull() to determine when you can call RecordSound() without blocking.

Returns: true if the sound has been recorded.

Parameters

file	Sound file recorded

virtual PBoolean PSoundChannel::RecordSound ( PSound & sound )

virtual

Record into the sound object all of the buffer's of sound data.

Use the SetBuffers() function to determine how long the recording will be made.

For the Win32 platform, the most efficient way to record a PSound is to use the SetBuffers() function to set a single buffer of the desired size and then do the recording. For Linux OSS this can cause problems as the buffers are rounded up to a power of two, so to gain more accuracy you need a number of smaller buffers.

Note that this function will block until all of the data is buffered. If you wish to do this asynchronously, use StartRecording() and AreAllrecordBuffersFull() to determine when you can call RecordSound() without blocking.

Returns: true if the sound has been recorded.

Parameters

sound Sound recorded

virtual PBoolean PSoundChannel::SetBuffers	(	PINDEX	size,
		PINDEX	count = `2`
	)

virtual

Set the internal buffers for the sound channel I/O.

Note that with Linux OSS, the size is always rounded up to the nearest power of two, so 20000 => 32768.

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

Parameters

size	Size of each buffer
count	Number of buffers

virtual PBoolean PSoundChannel::SetFormat	(	unsigned	numChannels = `1`,
		unsigned	sampleRate = `8000`,
		unsigned	bitsPerSample = `16`
	)

virtual

Set the format for play/record.

Note that linear PCM data is the only one supported at this time.

Note that if the PlayFile() function is used, this may be overridden by information in the file being played.

Returns: true if the format is valid.

Parameters

numChannels	Number of channels eg mono/stereo
sampleRate	Samples per second
bitsPerSample	Number of bits per sample

virtual bool PSoundChannel::SetMute ( bool mute )

virtual

Set the mute state of the play/read process.

Returns: true if there were no errors.

Parameters

mute	New mute state

virtual PBoolean PSoundChannel::SetVolume ( unsigned volume )

virtual

Set the volume of the play/read process.

The volume range is 0 == muted, 100 == LOUDEST. The volume is a logarithmic scale mapped from the lowest gain possible on the device to the highest gain.

Returns: true if there were no errors.

Parameters

volume New volume level

virtual PBoolean PSoundChannel::StartRecording ( )

virtual

Start filling record buffers.

The first call to Read() will also initiate the recording.

Returns: true if the sound driver has successfully started recording.

virtual PBoolean PSoundChannel::WaitForAllRecordBuffersFull ( )

virtual

Block the thread until all of the record buffer allocated has been filled.

There is an implicit Abort() of the recording if this occurs and recording is stopped. The channel may need to be closed and opened again to start a new recording.

Returns: true if the sound driver has filled a buffer.

virtual PBoolean PSoundChannel::WaitForPlayCompletion ( )

virtual

Block calling thread until the sound play begun with PlaySound() or PlayFile() has completed.

Returns: true if the sound has successfully completed playing.

virtual PBoolean PSoundChannel::WaitForRecordBufferFull ( )

virtual

Block the thread until a record buffer has been filled, so that the next Read() call will not block.

Provided that the amount of data read is less than the buffer size.

Returns: true if the sound driver has filled a buffer.

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

virtual

Low level write (or play) to the channel.

It will generate a logical assertion if you attempt write to a channel set up for recording.

Parameters

buf	is a pointer to the data to be written to the channel. It is an error for this pointer to be NULL. A logical assert will be generated when buf is NULL.
len	Nr of bytes to send. If len equals the buffer size set by SetBuffers() it will block for (1000len)/(samplesizesamplerate) ms. Typically, the sample size is 2 bytes. If len == 0, this will return immediately, where the return value is equal to the value of IsOpen().

Returns: true if len bytes were written to the channel, otherwise false. The GetErrorCode() function should be consulted after Write() returns false to determine what caused the failure.

Reimplemented from PChannel.

Member Data Documentation

Directions PSoundChannel::activeDirection

protected

This is the direction that this sound channel is opened for use in.

Should the user attempt to used this opened class instance in a direction opposite to that specified in activeDirection, an assert happens.

Referenced by GetDirection(), and GetDirectionText().

PSoundChannel* PSoundChannel::m_baseChannel

protected

PReadWriteMutex PSoundChannel::m_baseMutex

protected

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

sound.h

Public Member Functions

Protected Attributes

Construction

Open functions

Channel set up functions

Additional Inherited Members

Detailed Description

Member Enumeration Documentation

Constructor & Destructor Documentation

Member Function Documentation

Member Data Documentation