src/devices/media/index.jd

page.title=Media
@jd:body

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    <h2>In this document</h2>
    <ol id="auto-toc">
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<img style="float: right; margin: 0px 15px 15px 15px;"
src="images/ape_fwk_hal_media.png" alt="Android Media HAL icon"/>

<p>Android includes Stagefright, a media playback engine at the native level
that has built-in software-based codecs for popular media formats.</p>

<p>Stagefright audio and video playback features include integration with
OpenMAX codecs, session management, time-synchronized rendering, transport
control, and DRM.</p>

<p>Stagefright also supports integration with custom hardware codecs provided by
you. To set a hardware path to encode and decode media, you must implement a
hardware-based codec as an OpenMax IL (Integration Layer) component.</p>

<p class="note"><strong>Note:</strong> Stagefright updates can occur through the
Android <a href="{@docRoot}security/bulletin/index.html">monthly security
update</a> process and as part of an Android OS release.</p>

<h2 id="architecture">Architecture</h2>
<p>Media applications interact with the Android native multimedia framework
according to the following architecture.</p>
<img src="images/ape_fwk_media.png" alt="Android media architecture"
id="figure1" /><p class="img-caption"><strong>Figure 1.</strong> Media
architecture</p>

<dl>
<dt>Application Framework</dt>
<dd>At the application framework level is application code that utilizes
<a href="http://developer.android.com/reference/android/media/package-summary.html">android.media</a>
APIs to interact with the multimedia hardware.</dd>

<dt>Binder IPC</dt>
<dd>The Binder IPC proxies facilitate communication over process boundaries.
They are located in the <code>frameworks/av/media/libmedia</code> directory and
begin with the letter "I".</dd>

<dt>Native Multimedia Framework</dt>
<dd>At the native level, Android provides a multimedia framework that utilizes
the Stagefright engine for audio and video recording and playback. Stagefright
comes with a default list of supported software codecs and you can implement
your own hardware codec by using the OpenMax integration layer standard. For
more implementation details, see the MediaPlayer and Stagefright components
located in <code>frameworks/av/media</code>.</dd>

<dt>OpenMAX Integration Layer (IL)</dt>
<dd>The OpenMAX IL provides a standardized way for Stagefright to recognize and
use custom hardware-based multimedia codecs called components. You must provide
an OpenMAX plugin in the form of a shared library named
<code>libstagefrighthw.so</code>. This plugin links Stagefright with your custom
codec components, which must be implemented according to the OpenMAX IL
component standard.</dd>
</dl>

<h2 id="codecs">Implementing custom codecs</h2>
<p>Stagefright comes with built-in software codecs for common media formats, but
you can also add your own custom hardware codecs as OpenMAX components. To do
this, you must create the OMX components and an OMX plugin that hooks together
your custom codecs with the Stagefright framework. For example components, see
the <code>hardware/ti/omap4xxx/domx/</code>; for an example plugin for the
Galaxy Nexus, see <code>hardware/ti/omap4xx/libstagefrighthw</code>.</p>

<p>To add your own codecs:</p>
<ol>
<li>Create your components according to the OpenMAX IL component standard. The
component interface is located in the
<code>frameworks/native/include/media/OpenMAX/OMX_Component.h</code> file. To
learn more about the OpenMAX IL specification, refer to the
<a href="http://www.khronos.org/openmax/">OpenMAX website</a>.</li>
<li>Create a OpenMAX plugin that links your components with the Stagefright
service. For the interfaces to create the plugin, see
<code>frameworks/native/include/media/hardware/OMXPluginBase.h</code> and
<code>HardwareAPI.h</code> header files.</li>
<li>Build your plugin as a shared library with the name
<code>libstagefrighthw.so</code> in your product Makefile. For example:
<br>
<p><pre>LOCAL_MODULE := libstagefrighthw</pre></p>
<p>In your device's Makefile, ensure you declare the module as a product
package:</p>
<pre>
PRODUCT_PACKAGES += \
  libstagefrighthw \
  ...
</pre></li></ol>

<h2 id="expose">Exposing codecs to the framework</h2>
<p>The Stagefright service parses the <code>system/etc/media_codecs.xml</code>
and <code>system/etc/media_profiles.xml</code> to expose the supported codecs
and profiles on the device to app developers via the
<code>android.media.MediaCodecList</code> and
<code>android.media.CamcorderProfile</code> classes. You must create both files
in the <code>device/&lt;company&gt;/&lt;device&gt;/</code> directory
and copy this over to the system image's <code>system/etc</code> directory in
your device's Makefile. For example:</p>
<pre>
PRODUCT_COPY_FILES += \
  device/samsung/tuna/media_profiles.xml:system/etc/media_profiles.xml \
  device/samsung/tuna/media_codecs.xml:system/etc/media_codecs.xml \
</pre>

<p>For complete examples, seee <code>device/samsung/tuna/media_codecs.xml</code>
and <code>device/samsung/tuna/media_profiles.xml</code> .</p>

<p class="note"><strong>Note:</strong> As of Android 4.1, the
<code>&lt;Quirk&gt;</code> element for media codecs is no longer supported.</p>