1page.title=Media 2@jd:body 3 4<!-- 5 Copyright 2013 The Android Open Source Project 6 7 Licensed under the Apache License, Version 2.0 (the "License"); 8 you may not use this file except in compliance with the License. 9 You may obtain a copy of the License at 10 11 http://www.apache.org/licenses/LICENSE-2.0 12 13 Unless required by applicable law or agreed to in writing, software 14 distributed under the License is distributed on an "AS IS" BASIS, 15 WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 16 See the License for the specific language governing permissions and 17 limitations under the License. 18--> 19<div id="qv-wrapper"> 20 <div id="qv"> 21 <h2>In this document</h2> 22 <ol id="auto-toc"> 23 </ol> 24 </div> 25</div> 26 27<p> 28 Android provides a media playback engine at the native level called Stagefright that comes built-in with 29 software-based codecs for several popular media formats. Stagefright features for audio and video playback 30 include integration with OpenMAX codecs, session management, time-synchronized rendering, transport control, 31 and DRM. In addition, Stagefright supports integration with custom hardware codecs that you provide. 32 There actually isn't a HAL to implement for custom codecs, but to provide a hardware path to encode and 33 decode media, you must implement your hardware-based codec as an OpenMax IL (Integration Layer) component. 34</p> 35<h2 id="overview"> 36Overview 37</h2> 38<p>The following diagram shows how media applications interact with the Android native multimedia framework.</p> 39<p> 40 <img src="images/media.png"> 41</p> 42<dl> 43<dt>Application Framework</dt> 44 <dd>At the application framework level is the app's code, which utilizes the 45 <a href="http://developer.android.com/reference/android/media/package-summary.html">android.media</a> 46 APIs to interact with the multimedia hardware.</dd> 47 <dt>Binder IPC</dt> 48 <dd>The Binder IPC proxies facilitate communication over process boundaries. They are located in 49 the <code>frameworks/av/media/libmedia</code> directory and begin with the letter "I".</dd> 50 <dt>Native Multimedia Framework</dt> 51 <dd>At the native level, Android provides a multimedia framework that utilizes the Stagefright engine for 52 audio and video recording and playback. Stagefright comes with a default list of supported software codecs 53 and you can implement your own hardware codec by using the OpenMax integration layer standard. For more 54 implementation details, see the various MediaPlayer and Stagefright components located in 55 <code>frameworks/av/media</code>. 56 </dd> 57 <dt>OpenMAX Integration Layer (IL)</dt> 58 <dd>The OpenMAX IL provides a standardized way for Stagefright to recognize and use custom hardware-based 59 multimedia codecs called components. You must provide an OpenMAX plugin in the form of a shared library 60 named <code>libstagefrighthw.so</code>. This plugin links your custom codec components to Stagefright. 61 Your custom codecs must be implemented according to the OpenMAX IL component standard. 62 </dd> 63</dl> 64 65 66<h2 id="codecs"> 67Implementing Custom Codecs 68</h2> 69<p>Stagefright comes with built-in software codecs for common media formats, but you can also add your 70 own custom hardware codecs as OpenMAX components. To do this, you need to create OMX components and also an 71 OMX plugin that hooks together your custom codecs with the Stagefright framework. For an example, see 72 the <code>hardware/ti/omap4xxx/domx/</code> for example components and <code>hardware/ti/omap4xx/libstagefrighthw</code> 73 for an example plugin for the Galaxy Nexus. 74</p> 75 <p>To add your own codecs:</p> 76<ol> 77<li>Create your components according to the OpenMAX IL component standard. The component interface is located in the 78 <code>frameworks/native/include/media/OpenMAX/OMX_Component.h</code> file. To learn more about the 79 OpenMAX IL specification, see the <a href="http://www.khronos.org/openmax/">OpenMAX website</a>.</li> 80<li>Create a OpenMAX plugin that links your components with the Stagefright service. 81 See the <code>frameworks/native/include/media/hardware/OMXPluginBase.h</code> and <code>HardwareAPI.h</code> header 82 files for the interfaces to create the plugin. 83</li> 84<li>Build your plugin as a shared library with the name <code>libstagefrighthw.so</code> in your product Makefile. For example: 85<pre>LOCAL_MODULE := libstagefrighthw</pre> 86 87<p>In your device's Makefile, ensure that you declare the module as a product package:</p> 88<pre> 89PRODUCT_PACKAGES += \ 90 libstagefrighthw \ 91 ... 92</pre> 93</li> 94</ol> 95 96<h2 id="expose">Exposing Codecs to the Framework</h2> 97<p>The Stagefright service parses the <code>system/etc/media_codecs.xml</code> and <code>system/etc/media_profiles.xml</code> 98 to expose the supported codecs and profiles on the device to app developers via the <code>android.media.MediaCodecList</code> and 99 <code>android.media.CamcorderProfile</code> classes. You need to create both files in the 100 <code>device/<company_name>/<device_name>/</code> directory 101 and copy this over to the system image's <code>system/etc</code> directory in your device's Makefile. 102 For example:</p> 103 104 <pre> 105PRODUCT_COPY_FILES += \ 106 device/samsung/tuna/media_profiles.xml:system/etc/media_profiles.xml \ 107 device/samsung/tuna/media_codecs.xml:system/etc/media_codecs.xml \ 108</pre> 109 110<p>See the <code>device/samsung/tuna/media_codecs.xml</code> and 111 <code>device/samsung/tuna/media_profiles.xml</code> file for complete examples.</p> 112 113<p class="note"><strong>Note:</strong> The <code><Quirk></code> element for media codecs is no longer supported 114 by Android starting in Jelly Bean.</p> 115
