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<concept id="GUID-F46E4F89-B9ED-5A4A-B812-B605B925D0C0" xml:lang="en"><title>How to use the audio convert utility</title><prolog><metadata><keywords/></metadata></prolog><conbody>

<section id="GUID-06F005A3-F80A-5428-9AFE-0BF1B567BE6D"><title>Overview</title> <p>Audio convert utility is used to convert audio clips contained

in files or descriptors to other formats using the default codecs

provided by MMF. This functionality is implemented by the <xref href="GUID-810D29DA-8332-3E63-8A63-5B8A04EC9688.dita"><apiname>CMdaAudioConvertUtility</apiname></xref> class. </p> </section>

<section id="GUID-598B8280-09AB-4A60-9400-0AAE88A8DE4B"><title>Description</title> <p>Using a audio converter utility

involves the following tasks: </p> <ul>

<li id="GUID-707AF876-DBB4-5AE0-8610-A9E6B5A7D543"><p> <xref href="GUID-F46E4F89-B9ED-5A4A-B812-B605B925D0C0.dita#GUID-F46E4F89-B9ED-5A4A-B812-B605B925D0C0/GUID-8E3F0FF4-48D5-58E3-9F6B-643D7401EF47">Construct and open converter utility object</xref>  </p> </li>

<li id="GUID-0E4A77DB-0E03-5918-9EB1-8AF6F589490B"><p> <xref href="GUID-F46E4F89-B9ED-5A4A-B812-B605B925D0C0.dita#GUID-F46E4F89-B9ED-5A4A-B812-B605B925D0C0/GUID-F46111C2-E670-5A1D-A091-48B2BB959C1F">Configure conversion parameters</xref>  </p> </li>

<li id="GUID-CDCA30C1-7474-554F-A81E-5B13D36B7652"><p> <xref href="GUID-F46E4F89-B9ED-5A4A-B812-B605B925D0C0.dita#GUID-F46E4F89-B9ED-5A4A-B812-B605B925D0C0/GUID-5B8C4F5B-104E-58F8-A705-A3FD1E2B82FA">Convert audio clip</xref>  </p> </li>

<li id="GUID-07128D98-31E5-5090-B9CC-12FA2696A356"><p> <xref href="GUID-F46E4F89-B9ED-5A4A-B812-B605B925D0C0.dita#GUID-F46E4F89-B9ED-5A4A-B812-B605B925D0C0/GUID-785AFDB4-527A-5AEA-88F3-91F8E348E049">Change conversion position and crop audio data </xref>  </p> </li>

<li id="GUID-58C88A02-7CB2-541C-AE59-CB92511D0C1C"><p> <xref href="GUID-F46E4F89-B9ED-5A4A-B812-B605B925D0C0.dita#GUID-F46E4F89-B9ED-5A4A-B812-B605B925D0C0/GUID-E79175EB-EBAE-52FB-A594-04F2275A9A5F">Custom commands</xref>  </p> </li>

</ul> <p id="GUID-8E3F0FF4-48D5-58E3-9F6B-643D7401EF47"><b>Construct and open

converter utility object</b> </p> <p>The MMF provides a utility class

called <xref href="GUID-30F792FF-577D-36F3-9905-6AAAC53B25D5.dita"><apiname>CMdaAudioConverterUtility</apiname></xref>. Using this class,

you can convert audio clips from one format to another. The <xref href="GUID-30F792FF-577D-36F3-9905-6AAAC53B25D5.dita#GUID-30F792FF-577D-36F3-9905-6AAAC53B25D5/GUID-751B7E8A-4464-3DF0-96C0-B5BDA1200E57"><apiname>CMdaAudioConverterUtility::NewL()</apiname></xref> function need to be used

to construct an object of this utility class, with the following arguments: </p> <ul>

<li id="GUID-11759C41-FAE9-59C5-89DA-131537795AED"><p>An object of

the class, which inherits the <xref href="GUID-C18F29E7-6A66-320A-8F19-988BA1E4EAB9.dita"><apiname>MMdaObjectStateChangeObserver</apiname></xref> class to receive state change notifications from the converter object. </p> </li>

<li id="GUID-577C3B7C-30A4-5ECC-A38D-DCE762F8AA80"><p>Client's relative

priority, which can be <codeph>EMdaPriorityMin</codeph>, <codeph>EMdaPriorityNormal</codeph> or <codeph>EMdaPriorityMax</codeph>. </p> </li>

<li id="GUID-1639A961-D674-525A-8B59-C1837441BD3B"><p>An object of <xref href="GUID-0C8D114E-EE63-3A33-83AE-AB75B23E4E71.dita"><apiname>TMdaPriorityPreference</apiname></xref> specifying the behaviour, if a higher

priority client takes over the device. </p> </li>

</ul> <p>The following code shows how the client application <codeph>CClientApp</codeph> inherits the <xref href="GUID-C18F29E7-6A66-320A-8F19-988BA1E4EAB9.dita"><apiname>MMdaObjectStateChangeObserver</apiname></xref> and creates the audio converter utility object: </p> <codeblock id="GUID-0DD27445-881B-5A95-8E06-BE066206B429" xml:space="preserve">class CClientApp : public CBase, MMdaObjectStateChangeObserver

    {

public:

   void CClientApp();

protected:

    // from MMdaObjectStateChangeObserver

    virtual void MoscoStateChangeEvent(CBase *aObject, TInt aPreviousState, TInt aCurrentState, TInt aErrorCode);

protected:

    CMdaAudioConverterUtility*    iConverter;   

    };

void CClientApp()

{    

    iConverter = CMdaAudioConverterUtility::NewL(*this, EMdaPriorityNormal,

                   EMdaPriorityPreferenceTimeAndQuality);

}

</codeblock> <p>Once the audio converter utility object is constructed,

you can open an audio clip for conversion using the function <xref href="GUID-30F792FF-577D-36F3-9905-6AAAC53B25D5.dita#GUID-30F792FF-577D-36F3-9905-6AAAC53B25D5/GUID-B6F6968B-3731-3FD3-AE85-003786EFCBF9"><apiname>CMdaAudioConverterUtility::OpenL()</apiname></xref>. You can use the following

versions of this function: </p> <ul>

<li id="GUID-4AAA0055-3EC1-5B47-8ED9-8A1562F45292"><p>To open an existing

audio file and append the converted audio data to another file, use

the following version: </p> <codeblock id="GUID-32DB2AEF-251A-5C2A-AE73-6BCCB4DEAC48" xml:space="preserve">OpenL(const TDesC&amp; aPrimaryFile, const TdesC&amp; aSecondaryFile);</codeblock> <p>Where, <codeph>aPrimaryFile</codeph> and <codeph>aSecondaryFile</codeph> are used to specify the source and destination audio file names. </p> </li>

<li id="GUID-403A3496-1B71-5DE0-AF6D-56453E7FC349"><p>To open existing

audio file and store the converted audio data to either a file or

a descriptor, use the following version: </p> <codeblock id="GUID-E5DCD0F0-BB3E-5AE4-AA6F-2D9D3A43B9B9" xml:space="preserve">OpenL(const TdesC&amp; aPrimaryFile

        TMdaClipLocation* aLocation,

        TMdaClipFormat* aFormat,

        TMdaPackage* aArg1 = NULL,

        TMdaPackage* aArg2 = NULL);

</codeblock> <p>Where, <codeph>aPrimaryFile</codeph> specifies the

source audio file names. The <codeph>aLocation</codeph>, <codeph>aFormat</codeph>, <codeph>aArg1</codeph> and <codeph>aArg2</codeph> are used to specify

the target location for the converted audio data, target audio format,

codec for the target audio and target audio settings. </p> </li>

<li id="GUID-0A3D5957-920F-5232-85A0-F5137A6E9759"><p>To open audio

data either from a file or a descriptor source and store the resulting

data to either a file or descriptor, use the following version: </p> <codeblock id="GUID-51904005-0194-587B-BBAE-5DD14FF09593" xml:space="preserve">OpenL(TmdaClipLocation* aPriLocation

        TMdaClipLocation* aSecLocation,

        TMdaClipFormat* aPriFormat,

        TMdaClipFormat* aSecFormat,

        TMdaPackage* aPriArg1 = NULL,

        TMdaPackage* aPriArg2 = NULL,

        TMdaPackage* aSecArg1 = NULL,

        TMdaPackage* aSecArg2 = NULL);

</codeblock> <p>Where, <codeph>aPriLocation</codeph> and <codeph>aPriLocation</codeph> specifies the source and destination audio data locations. The <codeph>aPriFormat</codeph> and <codeph>aSecFormat</codeph> specifies the

audio format of the source and target audio data. The <codeph>aPriArg1</codeph> and <codeph>aPriArg2</codeph> specifies codec and settings for the

source audio data. Whereas, the <codeph>aSecArg1</codeph> and <codeph>aSecArg2</codeph> specifies the codec and settings for the target

audio data. </p> </li>

</ul> <p> <b>Note</b>: It is recommended to use the first version

of <codeph>OpenL</codeph> to specify source and destination audio

file location. The arguments for the other versions are deprecated. </p> <p>The following code uses the first version of OpenL to specify

source and destination audio location: </p> <codeblock id="GUID-AEAF18F8-C228-581A-ADBF-48B67E72E8B2" xml:space="preserve">TFileName fromFilename = _L("C:\\rectest2.wav");

TFileName toFilename = _L("C:\\rectest2.wav");

iConverter->OpenL(&fromFilename, &toFilename);

</codeblock> <p>Once the converter calls the <xref href="GUID-30F792FF-577D-36F3-9905-6AAAC53B25D5.dita#GUID-30F792FF-577D-36F3-9905-6AAAC53B25D5/GUID-B6F6968B-3731-3FD3-AE85-003786EFCBF9"><apiname>CMdaAudioConverterUtility::OpenL()</apiname></xref> function, the callback function <xref href="GUID-C18F29E7-6A66-320A-8F19-988BA1E4EAB9.dita#GUID-C18F29E7-6A66-320A-8F19-988BA1E4EAB9/GUID-4FD38520-962C-3FA3-9F29-012695B1841B"><apiname>MMdaObjectStateChangeObserver::MoscoStateChangeEvent()</apiname></xref> will notify the client application about the change in state of

the object. </p> <p id="GUID-F46111C2-E670-5A1D-A091-48B2BB959C1F"><b>Configure conversion

parameters</b> </p> <p>The configuration parameters can be broadly

classified into four categories as shown below: </p> <p><b>Set recorded file length </b> </p> <p>You can control the size

settings of a recorded file. This is handled by the <xref href="GUID-123B2967-5B45-3FE3-9FDB-937D254DBAC7.dita"><apiname>SetMaxWriteLength()</apiname></xref> function that sets the maximum number of bytes that can be written

to a recorded audio clip. The <xref href="GUID-123B2967-5B45-3FE3-9FDB-937D254DBAC7.dita"><apiname>SetMaxWriteLength()</apiname></xref> function is provided so that converters can limit the amount of

file storage or memory that should be allocated. If the maximum limit

is reached, MMF stops recording and notifies the client application. </p> <p>The following code sets the maximum number of bytes to 800: </p> <codeblock id="GUID-D472EA81-8859-573A-BEB1-36B5C12577B4" xml:space="preserve">iConverter-&gt;SetMaxWriteLength(800);</codeblock> <p><b>Formats and Codecs </b> </p> <p>You can report and set formats

and codecs for audio data that is already open. The four methods related

to DataTypes (codecs) enable you to retrieve a list of supported codecs

for the current data format, set a new codec to use or determine which

codec is currently in use. A further three methods are provided to

query and set the audio format to use. </p> <p>Codec related actions: </p> <ul>

<li id="GUID-BEFE741E-42F8-5A2A-A045-9DEED5351AF8"><p>To get the data

type of the destination audio clip, use the <xref href="GUID-DE1B22B0-EA40-3400-8880-B8D02FEA53AE.dita"><apiname>DestinationDataTypeL()</apiname></xref> function. </p> </li>

<li id="GUID-88543928-F6EA-5D88-A470-383203E328C5"><p>To set the data

type of the destination audio clip, use the <xref href="GUID-C63D3BEC-50E2-39F3-9F72-E5FC1E7EDBC3.dita"><apiname>SetDestinationDataTypeL()</apiname></xref> function. </p> </li>

<li id="GUID-11EC06F6-E79D-53CA-8A55-E5E2A709695A"><p>To get a list

of supported data types for the conversion destination, use the <xref href="GUID-C2183CDC-E0E9-3324-BF38-5CC970F8E465.dita"><apiname>GetSupportedDestinationDataTypesL()</apiname></xref> function. </p> </li>

<li id="GUID-FC20AD49-B7F3-55AE-9DC9-96751497FF70"><p>To get the data

type of the source audio clip, use the <xref href="GUID-7B7BB5C5-2435-3AA8-B320-46E7BB308F16.dita"><apiname>SourceDataTypeL()</apiname></xref> function. </p> </li>

</ul> <p>Data format related actions: </p> <ul>

<li id="GUID-63B22181-DCE4-5CF4-AACE-52F92F529821"><p>To get the format

of the destination audio clip, use the <xref href="GUID-E0245ACC-E3AE-36EB-9126-8D8325CA23AA.dita"><apiname>DestinationFormatL()</apiname></xref> function. </p> </li>

<li id="GUID-E3224695-C58D-5986-819B-E7178ADF7537"><p>To set the format

of the destination audio clip, use the <xref href="GUID-730E4D19-96E7-373D-BC5C-981866923767.dita"><apiname>SetDestinationFormatL()</apiname></xref> function. </p> </li>

<li id="GUID-C4A10676-7A39-50B1-807D-1F91B8CC3743"><p>To get the format

of the source audio clip, use the <xref href="GUID-37E7132D-6E48-38FE-9C00-77E4AE4320B9.dita"><apiname>SourceFormatL()</apiname></xref> function. </p> </li>

</ul> <p> <b>Note</b>: It is only possible to report the format and

codec used by the source audio and cannot be changed. </p> <p><b>Bit and sample rates </b> </p> <p>You can report and set bit and

sample rates as required by specific codecs. </p> <p>Methods to control

the bit rate of audio data: </p> <ul>

<li id="GUID-6F218910-6BDD-5553-9648-1F62305F3589"><p>To get a list

of supported bit rates to the conversion destination, use the <xref href="GUID-5777E279-44DB-3256-A2FC-A1E7056EA7C0.dita"><apiname>GetSupportedConversionBitRatesL()</apiname></xref> function. </p> </li>

<li id="GUID-6ED4056A-AFAC-5051-B77F-DB094C6470CD"><p>To get the bit

rate of the destination audio clip, use the <xref href="GUID-2701C3DD-5E86-34EB-BF46-1B7E59B35CE6.dita"><apiname>DestinationBitRateL()</apiname></xref> function. </p> </li>

<li id="GUID-7B6C2AF7-E5BA-548C-BB91-182C4285D0D3"><p>To set the bit

rate of the destination audio clip, use the <xref href="GUID-CD9399AE-0525-3E6F-8D1D-69F7DD9C3774.dita"><apiname>SetDestinationBitRateL()</apiname></xref> function. The bit rate must be one of the supported bit rates of

the audio target. Use the <xref href="GUID-5777E279-44DB-3256-A2FC-A1E7056EA7C0.dita"><apiname>GetSupportedConversionBitRatesL()</apiname></xref> function to retrieve a list of supported bit rates. </p> </li>

<li id="GUID-0D644C39-21EF-57DB-B1C3-EA6109E05AF0"><p>To get the bit

rate of the source audio clip, use the <xref href="GUID-A3511295-70AE-38D6-A362-334CD3722D26.dita"><apiname>SourceBitRateL()</apiname></xref> function. </p> </li>

</ul> <p> <b>Note</b>: None of the default codecs provided in the

MMF support the use of bit rates. These methods are provided to enable

the creation of additional codecs that might require bit rate information,

such as the audio format MP3. </p> <p>Methods for controlling the

sampling rate of audio data: </p> <ul>

<li id="GUID-C59895FE-BAF7-54E3-B5C9-8BC559EF1B32"><p>To get a list

of supported conversion sample rates, use the <xref href="GUID-1F8A204E-D666-37AA-8591-FC325684EF3E.dita"><apiname>GetSupportedConversionSampleRatesL()</apiname></xref> function. The list of sample rates is used by the conversion destination. </p> </li>

<li id="GUID-CB4C78D7-827D-5247-8832-8A7271087CAC"><p>To get the sample

rate of the conversion destination, use the <xref href="GUID-67DF026D-A62F-37F7-A581-388CF65B4E5A.dita"><apiname>DestinationSampleRateL()</apiname></xref> function. </p> </li>

<li id="GUID-390679E1-CB13-5722-B090-8E5001142FE3"><p>To set the sample

rate for the conversion destination, use the <xref href="GUID-71A4BDE9-4785-35E4-95CE-0AECF929C7D9.dita"><apiname>SetDestinationSampleRateL()</apiname></xref> function. The sample rate must be one of the supported sample rates

of the audio target. Use the <xref href="GUID-1F8A204E-D666-37AA-8591-FC325684EF3E.dita"><apiname>GetSupportedConversionSampleRatesL()</apiname></xref> function to retrieve a list of supported sample rates. </p> </li>

<li id="GUID-5A4D9803-D3FA-5C3E-A110-4B910A675B26"><p>To get the sample

rate of the source audio clip, use the <xref href="GUID-FBC478AB-D28C-3BB2-B4C7-6FD2111B00CC.dita"><apiname>SourceSampleRateL()</apiname></xref> function. </p> </li>

</ul> <p> <b>Note</b>: It is only possible to report the bit rate

or sample rate used by the source audio and cannot be changed. </p> <p><b>Balance </b> </p> <p>You can report and set the audio mode (mono

or stereo). </p> <ul>

<li id="GUID-AE349537-63C5-500A-96BC-FFD62CA6FA16"><p>To get a list

of the supported number of channels for conversion, use the <xref href="GUID-C5418287-E4F4-3E4A-B91C-64D814B8BA60.dita"><apiname>GetSupportedConversionNumberOfChannelsL()</apiname></xref> function. </p> </li>

<li id="GUID-36B76579-0DA0-5514-9E5F-3B7AAA31F16B"><p>To get the number

of channels the destination audio clip contains, use the <xref href="GUID-C954863D-701A-3A9A-AC60-00F3CB48F46F.dita"><apiname>DestinationNumberOfChannelsL()</apiname></xref> function. </p> </li>

<li id="GUID-B6CC8F43-C44F-5C1B-909F-4517C31844CF"><p>To set the number

of channels the destination audio clip contains, use the <xref href="GUID-87973927-F58D-3961-9777-E9E2A7C7DF22.dita"><apiname>SetDestinationNumberOfChannelsL()</apiname></xref> function. The number

of channels must be one of the values returned by <xref href="GUID-C5418287-E4F4-3E4A-B91C-64D814B8BA60.dita"><apiname>GetSupportedConversionNumberOfChannelsL()</apiname></xref>. </p> </li>

<li id="GUID-7C522973-402E-5231-9A51-76C640C13568"><p>To get the number

of channels used by the conversion source, use the <xref href="GUID-D74F993C-E4AA-3645-88FC-14C699423110.dita"><apiname>SourceNumberOfChannelsL()</apiname></xref> function. </p> </li>

</ul> <p> <b>Note</b>: It is only possible to report the number of

supported channels for the source audio and cannot be changed. </p> <p id="GUID-5B8C4F5B-104E-58F8-A705-A3FD1E2B82FA"><b> Convert audio clip</b> </p> <p>Several methods are provided in <xref href="GUID-810D29DA-8332-3E63-8A63-5B8A04EC9688.dita"><apiname>CMdaAudioConvertUtility</apiname></xref> to enable the conversion of audio data. The specific functions to

convert and perform related tasks are as follows: </p> <ul>

<li id="GUID-ED4D516E-EDD0-59D4-86C9-06E61189D2A5"><p>To start converting

audio data from the current position within the audio source and writing

the converted data to a play window within the destination file, use

the <xref href="GUID-F25BDC34-C955-312A-838E-09CA2EBAB418.dita"><apiname>ConvertL()</apiname></xref> function. </p> </li>

<li id="GUID-41EF4109-6406-5777-A696-72421DF6E4C4"><p>To stop audio

conversion, use the <xref href="GUID-7CBDCF0D-1D11-34D1-BF5C-1E5B50DA75B5.dita"><apiname>Stop()</apiname></xref> function. The positions

within the audio source and destination are maintained to handle subsequent <xref href="GUID-F25BDC34-C955-312A-838E-09CA2EBAB418.dita"><apiname>ConvertL()</apiname></xref> statements. </p> </li>

<li id="GUID-F1C55C8A-F965-5857-A488-4C029CFC6D07"><p>To stop audio

conversion and close all related controllers, use the <xref href="GUID-01D2AF56-21E1-3FF3-BF86-0C356A1658EF.dita"><apiname>Close()</apiname></xref> function. </p> </li>

</ul> <p id="GUID-785AFDB4-527A-5AEA-88F3-91F8E348E049"><b>Change conversion

position and crop audio data</b> </p> <p>It is possible to crop the

audio clip from the current position to the end of the clip or from

the begging to the current position as illustrated below: </p> <ul>

<li id="GUID-31CF2D85-4ACD-5B37-A4F9-67F435BE302C"><p>To crop the

current clip from the current position, use the <xref href="GUID-55FA7E3D-0137-3B74-8911-0D21D3038B85.dita"><apiname>CropL()</apiname></xref> function. The remainder of the clip is discarded. The effects of

the function cannot be undone. The function is synchronous and can

leave if there is a problem. The leave code depends on the configuration

settings. </p> </li>

<li id="GUID-70B87D7E-D4C2-5A26-B1D2-44315A404D4A"><p>To crop the

audio clip from the start of the file to the current position, use

the <xref href="GUID-EFB452A7-07A7-3AA8-988A-BD3EB2E1EF0A.dita"><apiname>CropFromBeginningL()</apiname></xref> function. The audio data

prior to the current position is discarded. The effects of the function

cannot be undone. The function is synchronous and can leave if there

is a problem. The leave code depends on the configuration settings. </p> </li>

</ul> <p>To retrieve the current position of the audio clip or move

the position to the desired location use the following functions: </p> <ul>

<li id="GUID-4764FACE-A6E6-58DE-81A2-B6DF19647673"><p>To get the current

position in the audio clip, use the <xref href="GUID-663106A9-3FA5-3471-A9C6-9D2FFD94FB7B.dita"><apiname>Position()</apiname></xref> function.

The position is defined in terms of a time interval measured from

the beginning of the audio sample data. </p> </li>

<li id="GUID-431A1E59-15CC-5463-83D5-64FE363369FA"><p>To set the current

position in the audio clip, use the <xref href="GUID-2C54E7FC-7C61-35FA-B129-1B15FFAC8F69.dita"><apiname>SetPosition()</apiname></xref> function. A subsequent call to the <xref href="GUID-F25BDC34-C955-312A-838E-09CA2EBAB418.dita"><apiname>ConvertL()</apiname></xref> function starts conversion from this new position. </p> </li>

</ul> <p id="GUID-E79175EB-EBAE-52FB-A594-04F2275A9A5F"><b> Custom commands</b> </p> <ul>

<li id="GUID-403EADC5-2D41-54F5-A97B-3484B754109B"><p>To send a raw

custom command synchronously to the controller or to allow data to

be returned from the controller, use the <xref href="GUID-8B88A239-C622-3952-9737-A7BEEA99AC9B.dita"><apiname>CustomCommandSync() </apiname></xref> function. </p> </li>

<li id="GUID-8958B82D-B1C5-5D27-B931-D957735955E4"><p>To send a raw

custom command asynchronously to the controller or to allows data

to be returned from the controller, use the <xref href="GUID-601DC50C-CD58-3604-98B2-35A7B5E6EBD8.dita"><apiname>CustomCommandAsync() </apiname></xref> function. </p> </li>

</ul> </section>

<section id="GUID-1AEF4A81-2898-46F5-AC26-E5DDA3E64061"><title>See Also</title> <p> <xref href="GUID-9EE78D5A-32BC-5E0F-9139-AF00CDB95CC1.dita">How to use the audio

tone player utility</xref>  </p> </section>

</conbody></concept>