CMdaAudioInputStream Class Reference

#include <mdaaudioinputstream.h>

Link against: mediaclientaudioinputstream.lib

class CMdaAudioInputStream : public CBase

Inherits from

CMdaAudioInputStream

Public Member Functions
	~CMdaAudioInputStream()
IMPORT_C TInt	BitRateL()
IMPORT_C TAny *	CustomInterface(TUid)
IMPORT_C TFourCC	DataType()
IMPORT_C TInt	Gain()
IMPORT_C TInt	GetBalanceL()
IMPORT_C TInt	GetBytes()
IMPORT_C void	GetSupportedBitRatesL(RArray< TInt > &)
IMPORT_C TInt	MaxGain()
IMPORT_C CMdaAudioInputStream *	NewL(MMdaAudioInputStreamCallback &)
IMPORT_C CMdaAudioInputStream *	NewL(MMdaAudioInputStreamCallback &, TInt, TInt)
IMPORT_C void	Open(TMdaPackage *)
IMPORT_C const TTimeIntervalMicroSeconds &	Position()
IMPORT_C void	ReadL(TDes8 &)
IMPORT_C void	RequestStop()
IMPORT_C void	SetAudioPropertiesL(TInt, TInt)
IMPORT_C void	SetBalanceL(TInt)
IMPORT_C void	SetBitRateL(TInt)
IMPORT_C void	SetDataTypeL(TFourCC)
IMPORT_C void	SetGain(TInt)
IMPORT_C void	SetPriority(TInt, TInt)
IMPORT_C void	SetSingleBufferMode(TBool)
IMPORT_C void	Stop()

Inherited Functions
	CBase::CBase()
	CBase::Delete(CBase *)
	CBase::Extension_(TUint,TAny &,TAny )
	CBase::operator new(TUint)
	CBase::operator new(TUint,TAny *)
	CBase::operator new(TUint,TLeave)
	CBase::operator new(TUint,TLeave,TUint)
	CBase::operator new(TUint,TUint)
	CBase::~CBase()

Detailed Description

The interface to an audio stream player passing raw audio data from the audio hardware to specified buffers.

This class enables MMF clients to:

Stream raw audio data from the audio hardware to specified buffers.

Specify the priority of the audio stream in relation to other clients that may request to use the same audio hardware.

Set the sample rate and the number of channels after successfully opening the stream. It is not possible to change these values once streaming has started.

Change the gain and balance before or while streaming is in progress. Gain and balance settings take effect immediately.

The API supports callbacks from the server to notify the client:

MaiscOpenComplete() will be called when the audio streaming object is open and ready to stream data back to the user as a result of a previous call to Open().

MaiscBufferCopied() will be called multiple times while the FIFO (queued via ReadL()) is emptied. Note: Each buffer will be flagged with KErrAbort if received after Stop() on is called. MaiscRecordComplete is called once all remaining buffers have been read.

MaiscRecordComplete() is called after Stop() has been called. aError - KErrAbort if MaiscRecordComplete called as a result of a call to Stop().

Users of object CMdaAudioInputStream should ensure that implementation of the callback methods MaiscOpenComplete,MaiscBufferCopied and MaiscRecordComplete in class MMdaAudioInputStreamCallback do not delete the object,otherwise a Kern-Exec 3 would occur during callback.

Constructor & Destructor Documentation

~CMdaAudioInputStream ( )

~CMdaAudioInputStream

(

)

Destructor.

Frees all resources owned by the object prior to its destruction.

Member Function Documentation

BitRateL ( )

IMPORT_C TInt

BitRateL

(

)

const

Returns the current bit rate.

leave: KErrNotSupported If the sound device does not support returning the current bit rate

Returns: The current bit rate, in bits per second.

CustomInterface ( TUid )

IMPORT_C TAny *

CustomInterface

(

TUid

aInterfaceId

)

Retrieves a custom interface to the underlying device.

Parameter	Description
aInterfaceId	The interface UID, defined with the custom interface.

Returns: A pointer to the interface implementation, or NULL if the device does not implement the interface requested. The return value must be cast to the correct type by the user.

DataType ( )

IMPORT_C TFourCC

DataType

(

)

const

Returns the current data type.

Returns: The ID of the data type.

Gain ( )

IMPORT_C TInt

Gain

(

)

const

Returns the current gain setting.

Returns: The current gain setting.

GetBalanceL ( )

IMPORT_C TInt

GetBalanceL

(

)

const

Returns the current audio balance.

Returns: The current balance value.

GetBytes ( )

IMPORT_C TInt

GetBytes

(

)

Returns the current number of bytes rendered by audio hardware.

Returns: The number of bytes.

GetSupportedBitRatesL ( RArray< TInt > & )

IMPORT_C void

GetSupportedBitRatesL

(

RArray< TInt > &

aSupportedBitRates

)

Returns the bit rates supported by the sound device

leave: KErrNotSupported If the sound device does not support setting the bit rate The supported bit rates, in bits per second, shall be appended to this array. Note that the array shall be reset by this method.

MaxGain ( )

IMPORT_C TInt

MaxGain

(

)

const

Returns the maximum gain level.

Returns: The maximum gain value that is supported by the sound device.

NewL ( MMdaAudioInputStreamCallback & )

IMPORT_C CMdaAudioInputStream *

NewL

(

MMdaAudioInputStreamCallback &

aCallBack

)

[static]

Instantiates a new audio input stream using default priority preferences.

capability: UserEnvironment For recording - the requesting client process must have a UserEnvironment capability.

Static NewL

Parameter	Description
aCallBack	A callback to notify the client when the input stream has been initialised and is ready for use, when data has been copied to a specified descriptor and when input streaming is stopped. The caller must create a callback class that implements this interface.

Returns: A pointer to the audio input stream object.CMdaAudioInputStream*

NewL ( MMdaAudioInputStreamCallback &, TInt, TInt )

IMPORT_C CMdaAudioInputStream *	NewL	(	MMdaAudioInputStreamCallback &	aCallBack,
			TInt	aPriority,
			TInt	aPref
		)	[static]

Instantiates a new audio input stream.

capability: UserEnvironment For recording - the requesting client process must have a UserEnvironment capability.

Note: The Priority Value and Priority Preference are used primarily when deciding what to do when several audio clients attempt to play or record simultaneously. In addition to the Priority Value and Preference, the adaptation may consider other parameters such as the SecureId and Capabilities of the client process. Whatever, the decision as to what to do in such situations is up to the audio adaptation, and may vary between different phones. Portable applications are advised not to assume any specific behaviour.

Static NewL

Parameter	Description
aCallBack	A callback to notify the client when the input stream has been initialised and is ready for use. The caller must create a callback class which implements this interface.
aPriority	The Priority Value - this client's relative priority. This is a value between EMdaPriorityMin and EMdaPriorityMax and represents a relative priority. A higher value indicates a more important request.
aPref	The Priority Preference - an additional audio policy parameter. The suggested default is EMdaPriorityPreferenceNone. Further values are given by TMdaPriorityPreference, and additional values may be supported by given phones and/or platforms, but should not be depended upon by portable code.

Returns: A pointer to the audio input stream object.CMdaAudioInputStream*

Open ( TMdaPackage * )

IMPORT_C void

Open

(

TMdaPackage *

aSettings

)

Opens an input audio stream package.

The MMdaAudioInputStreamCallback::MaisOpenComplete() callback function is called when the stream has been opened and is ready to record data. If the open was unsuccessful, this is indicated by the aError parameter of the callback.

Parameter	Description
aSettings	A pointer to an TMdaPackage object.

Position ( )

IMPORT_C const TTimeIntervalMicroSeconds &

Position

(

)

Returns the current position within the data stream in microseconds since the start of streaming.

Returns: The current position.

ReadL ( TDes8 & )

IMPORT_C void

ReadL

(

TDes8 &

aData

)

Records streaming raw audio data.

If this is the first ReadL() after a successful Open() this function starts the audio recording process.

The MMdaAudioInputStreamCallback::MaisBufferCopied() callback function is called when the buffer has been successfully filled. A pointer to the newly filled buffer is returned in the callback.

Note: The MMdaAudioInputStreamCallback::MaisBufferCopied() callback function is also called when a Stop() is issued, with a pointer to the remaining recorded audio data and the aError parameter of the callback set to indicate recording has finished.

Parameter	Description
aData	A reference to a buffer to be written into.

RequestStop ( )

IMPORT_C void

RequestStop

(

)

Requests a Stop of the recording process.

The device is requested to Stop and does so after all unprocessed buffers are processed and passed back to the input stream. The device is actually Stopped when the final empty buffer indicating buffer process completion is received.

SetAudioPropertiesL ( TInt, TInt )

IMPORT_C void	SetAudioPropertiesL	(	TInt	aSampleRate,
			TInt	aChannels
		)

Sets the sample rate and number of audio channels.

Parameter	Description
aSampleRate	The new sample rate. For possible values, see the TAudioCaps enum in class TMdaAudioDataSettings.
aChannels	The new number of channels. For possible values, see the TAudioCaps enum in class TMdaAudioDataSettings.

SetBalanceL ( TInt )

IMPORT_C void

SetBalanceL

(

TInt

aBalance = KMMFBalanceCenter

)

Sets the current audio balance.

The balance can be any value between KMMFBalanceMaxLeft and KMMFBalanceMaxRight, the default value being KMMFBalanceCenter.

Parameter	Description
aBalance	A specified balance value.

SetBitRateL ( TInt )

IMPORT_C void

SetBitRateL

(

TInt

aBitRate

)

Sets the bit rate to a new value.

leave: KErrNotSupported If the sound device does not support returning the current bit rate or the bit rate set is not supported

Parameter	Description
aBitRate	The new bit rate, in bits per second.

SetDataTypeL ( TFourCC )

IMPORT_C void

SetDataTypeL

(

TFourCC

aAudioType

)

Sets the data type. If the data type is not explicitly set it will assumed to be pcm16. If it is set then the hardware must support the data type being set otherwise the function leaves with KErrNotSupported.

leave: KErrNotSupported Leaves with this for any unsuported data type.

Parameter	Description
aAudioType	The fourCC code used to request the data type of the recorded data.

SetGain ( TInt )

IMPORT_C void

SetGain

(

TInt

aNewGain

)

Sets the gain for the audio device to a specified value.

Parameter	Description
aNewGain	The gain setting. This can be any value from zero to the value returned by a call to MaxGain(). A value which is less than zero is set to zero. A value which is greater than MaxGain() is set to MaxGain().

SetPriority ( TInt, TInt )

IMPORT_C void	SetPriority	(	TInt	aPriority,
			TInt	aPref
		)

Sets the audio priority values.

This function cannot be used while the stream object is open. It is intended for use before an Open() is issued, or between a previous Stop() and a new Open().

Parameter	Description
aPriority	The Priority Value.
aPref	The Priority Preference.

SetSingleBufferMode ( TBool )

IMPORT_C void

SetSingleBufferMode

(

TBool

aSingleMode

)

Indicates that the client wishes to use a single buffer to collect the data. This buffer is passed via the ReadL api.

Parameter	Description
aSingleMode	ETrue to indicate setting of single buffer mode and the use of a single buffer, EFalse to indicate use of multiple buffers.

Stop ( )

IMPORT_C void

Stop

(

)

Stops the recording process.

The MMdaAudioInputStreamCallback::MaisRecordComplete() callback function is called when recording has been halted. Just prior to issuing this callback, the FIFO buffers are read and the remaining audio data passed back by a final MMdaAudioInputStreamCallback::MaisBufferCopied() callback with its aError parameter set to KErrAbort.

Any remaining FIFO buffers are also passed back, with their aError parameter set to KErrAbort.

Stop is immediate and best used for premature stops, for example within destructors. If it is critical to receive all data buffers upto the point that Recording has Stopped, we recommend using RequestStop instead. Otherwise some trailing buffers may be lost from the recording process.

If a Stop is issued after a RequestStop, Stop will take precedent.