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aInputStream = CMdaAudioInputStream::NewL(aCallback, EMdaPriorityNormal, EMdaPriorityPreferenceTimeAndQuality);</codeblock> <p>where, <codeph>aCallback</codeph> is an <xref href="GUID-6A1EAD31-95CA-3CAC-8897-791E9D522DF0.dita"><apiname>MMdaAudioInputStreamCallback</apiname></xref> object. </p> </li> </ul> <p id="GUID-51B28404-61E7-54E8-9F4E-730315308EA2"><b>Basic Procedure to Open an Audio Input Stream</b> </p> <p>The high level steps to open an audio input stream are shown here: </p> <ol id="GUID-67E0F7C7-E2E3-5882-A21F-254CB2EEBDA3"><li id="GUID-B3AE7481-9750-5352-B10B-D51D1A220F97"><p>To open an input stream, use the <xref href="GUID-20D0D10F-3401-3F72-8AF6-DC35F6025DC2.dita"><apiname>Open()</apiname></xref> member function, which provides a pointer to the <xref href="GUID-06892E22-2EAC-305A-9D3A-F24E7F903427.dita"><apiname>TMdaPackage</apiname></xref> object with the required audio settings. You can also open the stream without the audio settings. For example: </p> <codeblock id="GUID-96065C5F-54F6-59D7-B6F1-BDE71EF46303" xml:space="preserve">aInputStream-&gt;Open(NULL);</codeblock> </li> <li id="GUID-8D443EF2-2FD1-5DBD-BEB3-21C5B7855978"><p>Once the stream is open, a <xref href="GUID-6A1EAD31-95CA-3CAC-8897-791E9D522DF0.dita#GUID-6A1EAD31-95CA-3CAC-8897-791E9D522DF0/GUID-1F9A4EAF-EE58-3FA4-8707-D8C5EDFC0664"><apiname>MMdaAudioInputStreamCallback::MaiscOpenComplete()</apiname></xref> is issued to indicate that the stream is ready for use. </p> <codeblock id="GUID-20F93B48-6662-59F1-A61B-374565A2FCB2" xml:space="preserve">void CIOStreamAudio::MaiscOpenComplete(TInt aError)

    {

    ASSERT(iState==EStateOpeningInput);

    if (aError!=KErrNone)

        {

        Complete(aError);

        }

    else

        {

        iMainBuffer.Zero();

        iState = EStateReading;

        ReadNextBlock(KNullDesC8); // kick off a new read - KNullDesC8 for first buffer

        }

    }</codeblock> </li> </ol> <p id="GUID-4EAC65E0-E108-5BAA-B338-5B19B82D5057"><b>Basic Procedure to Get and Set Stream Properties </b> </p> <p>The high level steps to get and set stream properties are shown here: </p> <ol id="GUID-98A49133-59B7-5681-9EC0-C19B1D71E9DD"><li id="GUID-DD84E50F-B44A-5ADC-ADF5-5DDE561D9AFD"><p>To set the sampling rate and number of audio channels, use the <xref href="GUID-38034819-8999-3EBE-9833-479D96D5DAB6.dita"><apiname>SetAudioPropertiesL()</apiname></xref> member function. You can do this only if the stream is open and if data is not being streamed. Values must be specified as enum values. For example, <xref href="GUID-CF54F882-E290-3C68-9352-79C6B7303FDF.dita#GUID-CF54F882-E290-3C68-9352-79C6B7303FDF/GUID-681C1220-0CDD-34BF-848F-9DC82CB001DB"><apiname>TMdaAudioDataSettings::ESampleRate8000Hz</apiname></xref> and not <codeph>8000</codeph> (Hz). The following code sets the sampling rate to 8000Hz and audio channel to mono: </p> <codeblock id="GUID-EBC071A0-A461-5000-80E5-D3579E690D18" xml:space="preserve">aInputStream-&gt;SetAudioPropertiesL(TMdaAudioDataSettings::ESampleRate8000Hz,TMdaAudioDataSettings::EChannelsMono));</codeblock> </li> <li id="GUID-EE508886-465A-581D-9FAF-76B5C522433F"><p>The <xref href="GUID-F4CC52C5-414A-3CA9-8472-A5C5298AC412.dita"><apiname>Gain()</apiname></xref> and <xref href="GUID-C2B76645-A50F-3DFF-943B-4F3D5A33ED31.dita"><apiname>GetBalanceL()</apiname></xref> member functions let you determine the current gain and balance settings. </p> </li> <li id="GUID-AEABCD16-7828-5DA1-B234-58BF44FB9C0E"><p>The <xref href="GUID-54851704-F44B-3C2C-B3C9-2B4537AD1472.dita"><apiname>SetGain()</apiname></xref> and <xref href="GUID-D1856981-6A17-3CD9-80B5-65781A803BA4.dita"><apiname>SetBalanceL()</apiname></xref> member functions let you set the gain and balance respectively. You can use them while the stream is open, with the new settings taking immediate effect. </p> </li> </ol> <p id="GUID-BD91C4E9-9BBA-5442-A72E-01B42160DBDA"><b>Basic Procedure to Read an Audio Input Stream</b> </p> <p>The high level steps to read an audio input stream are shown here: </p> <ol id="GUID-D78033B0-4918-51B8-8DC0-8B55F0172AC3"><li id="GUID-47C7BE03-0EAA-5C19-8FBB-7723B2AA9DEC"><p>To record the audio stream, use the <xref href="GUID-D7A48ABE-33F7-333E-8F57-0E673DA4B6F5.dita"><apiname>ReadL()</apiname></xref> member function, specifying the buffer to use. The first <xref href="GUID-D7A48ABE-33F7-333E-8F57-0E673DA4B6F5.dita"><apiname>ReadL()</apiname></xref> after a successful <xref href="GUID-20D0D10F-3401-3F72-8AF6-DC35F6025DC2.dita"><apiname>Open()</apiname></xref>, starts audio recording. Once the buffer is successfully recorded, a pointer to it is returned by <xref href="GUID-6A1EAD31-95CA-3CAC-8897-791E9D522DF0.dita#GUID-6A1EAD31-95CA-3CAC-8897-791E9D522DF0/GUID-FB4EC66A-4B6D-331B-B5A1-4605084343B0"><apiname>MMdaAudioInputStreamCallback::MaiscBufferCopied()</apiname></xref> callback. </p> <codeblock id="GUID-362E4E39-294E-57B9-912D-D0EB2C7B0B9B" xml:space="preserve">void CIOStreamAudio::MaiscBufferCopied(TInt aError, const TDesC8&amp; aBuffer)

    {

    ASSERT(iState==EStateReading);

    if (aError!=KErrNone)

        {

        if (aError!=KErrAbort) // aborts happen on Stop as buffers are recovered, need to ignore

            {

            Complete(aError);

            }

        }

    else

        {

        ReadNextBlock(aBuffer);

        }

    }</codeblock> </li> <li id="GUID-CD08610E-0AFE-5730-BC3A-8F112FF54EE5"><p>The following code reads the next audio block into the buffer in an array of descriptors: </p> <codeblock id="GUID-7E4D79D2-34DC-5691-865A-6C472B766BF8" xml:space="preserve">void CIOStreamAudio::ReadNextBlock(const TDesC8&amp; aBuffer)

    {

    ASSERT(iState==EStateReading);

    // buffer will be tail of iMainBuffer. Shift latter's length and get the next bit

    TInt lengthRecorded = iMainBuffer.Length()+aBuffer.Length();

    iMainBuffer.SetLength(lengthRecorded);

    iBufferPtr.Set(const_cast<TUint8*>(iMainBuffer.Ptr())+lengthRecorded, 0, iMainBuffer.MaxLength()-lengthRecorded);

    TRAPD(error, iInputStream->ReadL(iBufferPtr));

    if (error!=KErrNone)

        {

        Complete(error);

        }

    }</codeblock> </li> </ol> <p id="GUID-5811A2A0-5793-5FBB-B01A-AD94590955A8"><b>Basic Procedure to Stop an Audio Input Stream</b> </p> <p>The high level steps to stop an audio input stream are shown here: </p> <ul><li id="GUID-43677A50-198B-59D5-8F58-39C96CFAC5A4"><p>To stop recording the audio stream, use the <xref href="GUID-7CBDCF0D-1D11-34D1-BF5C-1E5B50DA75B5.dita"><apiname>Stop()</apiname></xref> member function. Two callbacks are issued after a <codeph>Stop()</codeph>. </p> <ol id="GUID-591B7B4E-899D-5D28-B33D-3EFC2DE1B4D6"><li id="GUID-EE9F9106-E0E8-5C20-8D8E-CB2A9FCCD0C4"><p>An <xref href="GUID-6A1EAD31-95CA-3CAC-8897-791E9D522DF0.dita#GUID-6A1EAD31-95CA-3CAC-8897-791E9D522DF0/GUID-FB4EC66A-4B6D-331B-B5A1-4605084343B0"><apiname>MMdaAudioInputStreamCallback::MaiscBufferCopied()</apiname></xref> pointing to a buffer that contains the last of the recorded audio data (and an <codeph>aError</codeph> value of <codeph>KErrAbort</codeph>). </p> </li> <li id="GUID-E3EBC7BE-C12C-527C-BF33-3EF787D8F9F4"><p>An <xref href="GUID-6A1EAD31-95CA-3CAC-8897-791E9D522DF0.dita#GUID-6A1EAD31-95CA-3CAC-8897-791E9D522DF0/GUID-23F823E5-46A4-34D1-A7DD-DF6B18C37445"><apiname>MMdaAudioInputStreamCallback::MaiscRecordComplete()</apiname></xref>, indicating successful closure of the audio stream. </p> <codeblock id="GUID-A9CE4580-E981-56E8-B98B-05C84E3C746E" xml:space="preserve">void CIOStreamAudio::MaiscRecordComplete(TInt aError)

    {

    ASSERT(iState==EStateReading && aError!=KErrNone);

    Complete(aError);

    }</codeblock> </li> </ol> </li> </ul> </section> <section><title>See Also</title> <p><xref href="GUID-ECBA6331-2187-52C9-A5DF-20CD1EEFE781.dita">Audio Output Streaming Tutorial</xref>  </p> </section> </conbody></concept>