<?xml version="1.0" encoding="utf-8"?>

<!-- Copyright (c) 2007-2010 Nokia Corporation and/or its subsidiary(-ies) All rights reserved. -->

<!-- This component and the accompanying materials are made available under the terms of the License 

"Eclipse Public License v1.0" which accompanies this distribution, 

and is available at the URL "http://www.eclipse.org/legal/epl-v10.html". -->

<!-- Initial Contributors:

    Nokia Corporation - initial contribution.

Contributors: 

-->

<!DOCTYPE concept

  PUBLIC "-//OASIS//DTD DITA Concept//EN" "concept.dtd">

<concept id="GUID-D62A282E-9DEA-5EF3-A606-20647BC5049D" xml:lang="en"><title>Audio Client Overview </title><prolog><metadata><keywords/></metadata></prolog><conbody>

<p>This document provides an overview of the Audio Client. </p>

<section id="GUID-DBB3FA4E-B6E7-4545-8C15-F58DE69780DA"><title>Purpose</title> <p>The Audio Client provides an interface

to: </p> <ul>

<li id="GUID-E1752C25-893D-5859-A9B7-C527AC115044"><p>Play back, record,

and convert sound clips. </p> </li>

<li id="GUID-5AF02D1B-25A9-59F0-B57B-7F0CAE7EB07D"><p>Play tone sequences

and DTMF (Dual-Tone Multi-Frequency) strings. </p> </li>

</ul> <p><b>Audio Client Library Details</b> </p> <p>The DLL that provides

the functionality and the library to which your code must link is

identified below. </p> <table id="GUID-28BCAB7A-147C-5519-8833-62ACA430C4D3">

<tgroup cols="3"><colspec colname="col0"/><colspec colname="col1"/>

<colspec colname="col2"/>

<thead>

<row>

<entry>DLL</entry>

<entry>LIB</entry>

<entry>Short Description</entry>

</row>

</thead>

<tbody>

<row>

<entry><p> <b>mediaclientaudio.dll</b>  </p> </entry>

<entry><p> <b>mediaclientaudio.lib</b>  </p> </entry>

<entry><p>These files are used for implementing the Audio Client. </p> </entry>

</row>

</tbody>

</tgroup>

</table> </section>

<section id="GUID-24255721-6198-4D8A-A560-DC86C14E92A7"><title>Architectural Relationship</title> <p>The methods

for recording, converting, and playing audio clips or tones interact

with the lower levels of MMF (known as the controller framework).

The controller framework is in turn responsible for managing the interface

to audio hardware. On some phones, this is implemented as a device

driver; on others it may be implemented as a connection to a lower

level hardware controller. </p> <p>Clients using any of the <xref href="GUID-29FB1DE6-D00C-3E6B-A8AA-476FAFD7F26C.dita"><apiname>CMdaAudioRecorderUtility</apiname></xref>, <xref href="GUID-810D29DA-8332-3E63-8A63-5B8A04EC9688.dita"><apiname>CMdaAudioConvertUtility</apiname></xref>, <xref href="GUID-778D24B5-A68E-3C91-B66A-69007FBA4791.dita"><apiname>CMdaAudioPlayerUtility</apiname></xref> or <xref href="GUID-D728A286-A202-3915-9643-8FD70646F78A.dita"><apiname>CMdaAudioToneUtility</apiname></xref> classes must have an active scheduler running in their thread because

the implementations use active objects and callbacks. </p> <p>How

the tone player class interacts with other components of MMF is shown

below. </p> <fig id="GUID-8273BE86-D5F9-528F-9147-0C0C58D9ABCD">

<title>              Audio tone player overview            </title>

<image href="GUID-4F879832-8425-5C56-B3FE-4C4592EBB6A5_d0e520043_href.png" placement="inline"/>

</fig> </section>

<section id="GUID-B41E6DF0-5963-4AF8-822E-473380A1CE78"><title>Description</title> <p><b>Audio Playing, Recording, and Conversion</b> </p> <p>All three

of the audio classes are plugin based, leaving the list of supported

audio formats for input and output open ended. The audio file formats

supported as standard by MMF are: AU, WAV and raw audio data. Each

file format may support one or more compression algorithms (codecs).

The standard file formats and corresponding codecs are shown below: </p> <table id="GUID-058548B8-0DEF-5E61-B9A1-6FEC07DCAA8A">

<tgroup cols="2"><colspec colname="col0"/><colspec colname="col1"/>

<thead>

<row>

<entry>Audio file format</entry>

<entry>Codecs supported</entry>

</row>

</thead>

<tbody>

<row>

<entry><p>AU </p> </entry>

<entry><p>A-Law, mu-law, signed 16 bit PCM big-endian, signed 8 bit

PCM </p> </entry>

</row>

<row>

<entry><p>WAV </p> </entry>

<entry><p>IMA-ADPCM, A-Law, mu-law, unsigned 8 bit PCM, gsm 6.10,

signed 16 bit PCM </p> </entry>

</row>

<row>

<entry><p>raw data </p> </entry>

<entry><p>Signed big-endian 16 bit PCM, signed 16 bit PCM, unsigned

16 bit PCM </p> </entry>

</row>

</tbody>

</tgroup>

</table> <p>Input and output audio data can be of any format supported

by the installed plugins. When possible MMF uses a plugin resolver

to determine the format and codecs to use. It determines this by checking

the filename extension and reading any header data that may be present

in the audio clip. The plugin resolver cannot determine the format

and codecs to use for raw audio, so in such cases you must specify

this information yourself. A full list of supported plugins can be

retrieved by using <xref href="GUID-810D29DA-8332-3E63-8A63-5B8A04EC9688.dita#GUID-810D29DA-8332-3E63-8A63-5B8A04EC9688/GUID-D0456E01-109E-3C93-949D-0452B09E886F"><apiname>CMdaAudioConvertUtility::GetSupportedDestinationDataTypesL()</apiname></xref>. </p> <p> <b> Note:</b> All audio clips can be uniquely identified

for purposes of plugin assignment by their format (gsm z6.10, AU,

WAV and so on) and their codec (for example for AU, valid codecs include

A-Law, mu-law, signed 16 bit PCM big-endian, signed 8 bit PCM). Each

format and codec has an arbitrary ID assigned to it by MMF and its

associated plugin, for use with the "Open" functions of both <codeph>CMdaAudioConvertUtility</codeph> and <codeph>CMdaAudioRecorderUtility</codeph>. </p> <p id="GUID-B99776D8-B713-5C18-AB32-3BF13EDDFEBB"><b>Tone Playing</b> </p> <p>The Audio Client provide a simple interface for tone generation

(synthesized sounds) that enables the playing of tone sequences and

DTMF (Dual-Tone Multi-Frequency) strings. The tone player functionality

is provided by the <xref href="GUID-D728A286-A202-3915-9643-8FD70646F78A.dita"><apiname>CMdaAudioToneUtility</apiname></xref> class and

using this class you can play: </p> <ul>

<li id="GUID-5B1FD304-5905-5F3A-97C6-237A59F911A1"><p>Single tones

of a specified duration and frequency. </p> </li>

<li id="GUID-6CD5A5D6-8659-5DDB-B773-1513C663E4F6"><p>DTMF strings. </p> </li>

<li id="GUID-9F98BD96-C5F6-5100-96FB-EA8396AE0364"><p>Sequences of

tones held in files or descriptors. </p> </li>

<li id="GUID-B27D9870-E9AE-5280-A144-E4C24AA91E09"><p>Predefined (fixed)

sequences of tones held in the mobile equipment. </p> </li>

</ul> </section>

<section id="GUID-7655A8EA-ADE9-4CDE-95D9-27055E14122D"><title>Key Audio Client Classes</title> <p>The functionality

provided by the Audio Client is contained within the following classes: </p> <ul>

<li id="GUID-0EF967E4-CFE1-5528-9EAB-BA0A2E71C6D3"><p> <xref href="GUID-29FB1DE6-D00C-3E6B-A8AA-476FAFD7F26C.dita"><apiname>CMdaAudioRecorderUtility</apiname></xref>  </p> </li>

<li id="GUID-93D94E92-E9E6-523B-9C4B-02DF91D9976E"><p> <xref href="GUID-810D29DA-8332-3E63-8A63-5B8A04EC9688.dita"><apiname>CMdaAudioConvertUtility</apiname></xref>  </p> </li>

<li id="GUID-CBD9AF2F-BB55-5D03-A87B-A7A23AAA4CD5"><p> <xref href="GUID-778D24B5-A68E-3C91-B66A-69007FBA4791.dita"><apiname>CMdaAudioPlayerUtility</apiname></xref>  </p> </li>

<li id="GUID-3B16D9CB-B192-548F-B096-5BA7B0E89344"><p> <xref href="GUID-D728A286-A202-3915-9643-8FD70646F78A.dita"><apiname>CMdaAudioToneUtility</apiname></xref> <xref href="GUID-6BD89347-671F-3518-9777-55801A090C79.dita"><apiname/></xref>  </p> </li>

</ul> </section>

<section id="GUID-CD24BD19-FCE1-4F3E-8E1D-906FC63AD238"><title>Using the Audio Client</title> <p>Clients can use

the Audio Client to: </p> <ul>

<li id="GUID-AB6FC77A-FD23-55F0-9A07-916D388CE19D"><p>Manipulate audio

sources and sinks, add, retrieve and modify meta data and record audio

data to files or descriptors. </p> </li>

<li id="GUID-8557E211-D6E7-59FF-AE63-939A0BCBF3C4"><p>Convert audio

clips contained in files or descriptors to other formats using the

default codecs provided by MMF. </p> </li>

<li id="GUID-E9D2FB84-0CF1-5873-BC5B-005869025A91"><p>Play audio clips

contained in files, descriptors or URLs. </p> </li>

<li id="GUID-C3C75693-4113-5684-9643-2C6DC1A5BCB0"><p>Play single

tones, DTMF strings and tone sequences. </p> </li>

</ul> </section>

<section id="GUID-04F7EA21-F6B4-4C37-A37E-F86B3C94FCD3"><title>See Also</title> <p><xref href="GUID-F46E4F89-B9ED-5A4A-B812-B605B925D0C0.dita">How to use the audio

convert utility</xref>  </p> <p><xref href="GUID-9EE78D5A-32BC-5E0F-9139-AF00CDB95CC1.dita">How to use the audio

tone player utility</xref>  </p> <p><xref href="GUID-2D3F7471-9B92-5E49-B8BC-E0FA7AA709D7.dita">DevSound Overview</xref>  </p> </section>

</conbody></concept>