xref: /frameworks/base/docs/html/about/versions/kitkat.jd

page.title=KitKat

@jd:body


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<!-- BEGIN ANDROID 4.4 -->
<div id="44-android-44" class="version-section">

  <div style="padding:0px 0px 0px 60px;margin-top:-3px;float:right;">
    <img src="{@docRoot}images/kk-android-44.png" alt="Android 4.3 on phone and tablet" width="380"> 
  </div>

  <div class="landing-docs" style="float:right;clear:both;margin:22px 0 2em 3em;">
  <div class="col-4 normal-links highlights" style="font-size:12px;">
    <h3 id="thisd" >Key Developer Features</h3>
    <ul style="list-style-type:none;">
      <!--<li><a href="#44-ui">UI refresh</a></li>-->
      <li><a href="#44-hce">Host Card Emulation</a></li>
      <li><a href="#44-printing">Printing framework</a></li>
      <li><a href="#44-storage-access">Storage access framework</a></li>
      <li><a href="#44-sensors">Low-power sensors</a></li>
      <li><a href="#44-sms-provider">SMS provider</a></li>
      <li><a href="#44-immersive">Full-screen Immersive mode</a></li>
      <li><a href="#44-transitions">Transitions framework</a></li>
      <li><a href="#44-webview">Chromium WebView</a></li>
      <li><a href="#44-screen-recording">Screen recording</a></li>
      <li><a href="#44-renderscript-ndk">RenderScript NDK</a></li>
      <li><a href="#44-bluetooth">Bluetooth HOGP and MAP</a></li>
      <li><a href="#44-ir-blasters">IR Blasters</a></li>
      <li><a href="#44-closed-captioning">Closed captioning settings</a></li>
      <li><a href="#44-international-users">RTL features</a></li>
      <li><a href="#44-security">Security enhancements</a></li>
      <li><a href="#44-tools">Tools for analyzing memory use</a></li>
    </ul>
  </div>
</div>


<p>Welcome to Android 4.4 KitKat!</p>

<p>Android KitKat brings all of Android's 
most innovative, most beautiful, and most useful features to more devices everywhere. </p>
<p>This document provides a glimpse of what's new for
developers. </p>
<p>Find out more about KitKat for consumers at <a
href="http://www.android.com/whatsnew">www.android.com</a>.</p> 


<h2 id="svelte" style="line-height:1.25em;">Making Android for everyone</h2>

<p><span style="white-space:nowrap;">Android 4.4</span> is designed to run fast, smooth,
  and responsively on a much broader range of devices than ever before &mdash; including
  on millions of entry-level devices around the world that have as little as <strong>512MB
  RAM</strong>. </p>

<!--<p>Now in KitKat, Android brings all of
its most innovative, most beautiful, and most useful features and APIs to devices everywhere. </p>-->
<p>KitKat streamlines every major component to reduce memory use and introduces new APIs
  and tools to help you create innovative, responsive, memory-efficient applications. 

<p>OEMs building the next generation of Android devices can take advantage of <strong>targeted recommendations
  and options</strong> to run <span style="white-space:nowrap;">Android 4.4</span> efficiently, even on low-memory devices. Dalvik JIT code cache tuning,
  kernel samepage merging (KSM), swap to zRAM, and other optimizations help manage
  memory. New configuration options let OEMs tune out-of-memory levels for processes, set graphics cache sizes,
  control memory reclaim, and more. </p>

<p>In Android itself, changes across the system improve memory management and reduce
  memory footprint.  Core system processes are trimmed to <strong>use less heap</strong>, and they now
  more <strong>aggressively protect system memory</strong> by killing long-running cached and idle
  processes that consume large memory. When multiple services start at once &mdash; such
  as when network connectivity changes &mdash; Android now <strong>launches the services serially</strong>,
  in small groups, to avoid peak memory demands.</p>

<p>For developers, <span style="white-space:nowrap;">Android 4.4</span> helps you deliver <strong>apps that are efficient and responsive</strong> on all devices. A new API,
  <span style="font-size:11.5px;font-family:monospace;">ActivityManager.isLowRamDevice()</span>,
  lets you tune your app's
  behavior to match the device's memory configuration. You can modify or disable large-memory features
  as needed, depending on the use-cases you want to support on entry-level devices. Learn more about optimizing your apps for low-memory devices <a href="">here</a>.</p>

<p>New tools give also give you powerful insight into your app's memory use. The <strong>procstats tool</strong> details memory use over time, 
  with run times and memory footprint for foreground
  apps and background services. An on-device view is also available as a new developer option. The <strong>meminfo tool</strong> is also enhanced to
  make it easier to spot memory trends and issues, and it reveals additional memory
  overhead that hasn't previously been visible. </p>

<!--
  <p>With memory effieciency and , along with the new advantage of memory-saving <span style="font-size:11px;font-family:monospace;">ArrayMap/ArraySet</span>
  APIs, along many other high-performance, low-power APIs and capabilities in <span style="white-space:nowrap;">Android 4.4</span>. -->

<h2 id="44-hce">New NFC capabilities through Host Card Emulation</h2>

<p><span style="white-space:nowrap;">Android 4.4</span> introduces new platform support for secure NFC-based transactions 
through <strong>Host Card Emulation</strong> (HCE), for payments, loyalty programs, 
card access, transit passes, and other custom services. With HCE, any app on an 
Android device can emulate an NFC smart card, letting users tap to initiate 
transactions with an app of their choice &mdash; no provisioned secure element (SE) 
in the device is needed. Apps can also use a new Reader Mode to act as readers 
for HCE cards and other NFC-based transactions.</p>

<div style="float:right;margin:32px;width:200px;">
  <img src="{@docRoot}images/kk-contactless-card.png" alt="" width="200" style="margin-bottom:0;">
<!--<p class="img-caption" style="padding-top:1.5em;margin-left:6px;line-height:1.25em;width:480px;">You can add printing support to your apps or develop print services to support specific types of printers.</p>-->
</div>

<p>Android HCE emulates ISO/IEC 7816 based smart cards that use the contactless 
ISO/IEC 14443-4 (ISO-DEP) protocol for transmission. These cards are used by 
many systems today, including the existing EMVCO NFC payment infrastructure. 
Android uses Application Identifiers (AIDs) as defined in ISO/IEC 7816-4 as the 
basis for routing transactions to the correct Android applications.</p>

<p>Apps declare the AIDs they support in their manifest files, along with a 
category identifier that indicates the type of support available (for example, 
"payments"). In cases where multiple apps support the same AID in the same 
category, Android displays a dialog that lets the user choose which app to use. </p>

<p>When the user taps to pay at a point-of-sale terminal, the system extracts the 
preferred AID and routes the transaction to the correct application. The app 
reads the transaction data and can use any local or network-based services to 
verify and then complete the transaction. </p>

<p>Android HCE requires an NFC controller to be present in the device. Support for 
HCE is already widely available on most NFC controllers, which offer dynamic 
support for both HCE and SE transactions. <span style="white-space:nowrap;">Android 4.4</span> devices that support NFC 
will include Tap &amp; Pay for easy payments using HCE.</p>

<h2 id="44-printing">Printing framework</h2>

<p>Android apps can now <strong>print any type of content</strong> over Wi-Fi or 
cloud-hosted services such as Google Cloud Print. In print-enabled apps, users 
can discover available printers, change paper sizes, choose specific pages to 
print, and print almost any kind of document, image, or file. </p>

<p><span style="white-space:nowrap;">Android 4.4</span> introduces native platform support for printing, along with APIs for 
managing printing and adding new types of printer support. The platform provides 
a print manager that mediates between apps requesting printing and installed 
print services that handle print requests. The print manager provides shared 
services and a system UI for printing, giving users consistent control over 
printing from any app. The print manager also ensures the security of content as 
it's passed across processes, from an app to a print service.</p>

<div style="float:right;margin:22px 0px 0px 24px;width:490px;">
  <img src="{@docRoot}images/kk-print-land-n5.png" alt="" width="471" style="margin-bottom:0;">
<p class="img-caption" style="padding-top:1.5em;margin-left:6px;line-height:1.25em;width:480px;">You can add printing support to your apps or develop print services to support specific types of printers.</p>
</div>



<p>Printer manufacturers can use new APIs to develop their own <strong>print services</strong> &mdash; 
pluggable components that add vendor-specific logic and services for 
communicating with specific types of printers. They can build print services and 
distribute them through Google Play, making it easy for users to find and 
install them on their devices. Just as with other apps, you can update print 
services over-the-air at any time.</p>

<p>App developers can use new APIs to <strong>add printing capabilities</strong> to their apps with 
minimal code changes. In most cases, you would add a print action to your Action 
Bar and a UI for choosing items to print. You would also implement APIs to 
create print jobs, query the print manager for status, and cancel jobs. This 
lets you print nearly any type of content, from local images and documents to 
network data or a view rendered to a canvas. </p>

<p>For broadest compatibility, Android uses PDF as its primary file format for 
printing. Before printing, your app needs to generate a properly paginated PDF 
version of your content. For convenience, the printing API provides native and 
WebView helper classes to let you create PDFs using standard Android drawing 
APIs. If your app knows how to draw the content, it can quickly create a PDF for 
printing.</p>

<p>Most devices running <span style="white-space:nowrap;">Android 4.4</span> will include Google Cloud Print pre-installed 
as a print service, as well as several Google apps that support printing, 
including Chrome, Drive, Gallery, and QuickOffice.</p>

<h2 id="44-storage-access">Storage access framework</h2>


<p>A new storage access framework makes it 
simple for users to browse and open documents, images, and other files across 
all of their their preferred document storage providers. A 
standard, easy-to-use UI lets users browse files and access recents in a consistent way across apps and providers.</p>

<div style="float:right;margin:22px 0px 0px 24px;width:490px;">
  <img src="{@docRoot}images/kk-saf2-n5.png" alt="" width="240" style="margin-bottom:0;">
<img src="{@docRoot}images/kk-saf1-n5.png" alt="" width="240" style="margin-bottom:0;padding-left:6px;">

<p class="img-caption" style="padding-top:1.5em;margin-left:6px;line-height:1.25em;width:480px;">The storage access framework brings users, apps, and storage services together in a single convenient ecosystem.</p>
</div>



<p>Storage services can participate in this ecosystem by implementing a new 
document provider class that encapsulates their services. The provider class 
includes all of the APIs needed to register the provider with the system and 
manage browsing, reading, and writing documents in the provider. The document 
provider can give users access to any local or remote data that can be 
represented as files &mdash; from text, photos, and wallpapers to video, audio, and 
more. </p>

<p>If you build a document provider for a local or cloud-based service, you can 
deliver it to users as part of your existing Android app. After downloading and 
installing the app, users will have instant access your service from any app 
that participates in the framework. This can help you gain exposure and user 
engagement, since users will find your services more easily.</p>

<p>If you develop an app that manages files or documents, you can integrate with 
the storage access framework just by using new <span style ="font-size:11.5px;">CREATE_DOCUMENT</span>
or <span style ="font-size:11.5px;">OPEN_DOCUMENT</span>
intents to open or create files &mdash; the system automatically displays the 
standard UI for browsing documents, including all available document providers. 

<p>You can integrate your app one time, for all providers, without any
  vendor-specific code. As users add or remove providers, they’ll continue to
  have access to their preferred services from your app, without changes or
  updates needed in your code.</p>

<p>
  The storage access framework is integrated with the existing <span style=
  "font-size:11.5px;">GET_CONTENT</span> intent, so users also have access to
  all of their previous content and data sources from the new system UI for
  browsing. Apps can continue using <span style=
  "font-size:11.5px;">GET_CONTENT</span> as a way to let users import data. The
  storage access framework and system UI for browsing make it easier for users
  to find and import their data from a wider range of sources.
</p>

<p>Most devices running <span style="white-space:nowrap;">Android 4.4</span> will include Google Drive and local
  storage pre-integrated as document providers, and Google apps that work
  with files also use the new framework. </p>


<h2 id="44-sensors">Low-power sensors</h2>



<!--<div style="float:right;padding-top:0em;width:372px;margin-left:2em;">

<img src="{@docRoot}images/kk-rs-chart-versions.png" alt="Renderscipt optimizations chart" width="360" height="252" style="border:1px solid #ddd;border-radius: 6px;" />
<p class="img-caption" style="margin-left:6px;line-height:1.25em;">Performance benchmarks for Android&nbsp;4.4 relative to Android&nbsp;4.3, run on the same devices (Nexus 7, Nexus 10).</p>
</div> -->

<h4 id="44-sensor-batching">Sensor batching</h4>

<p><span style="white-space:nowrap;">Android 4.4</span> introduces platform support for hardware sensor batching, a new 
optimization that can dramatically reduce power consumed by ongoing sensor 
activities. </p>

<p>With sensor batching, Android works with the device hardware to 
collect and deliver sensor events efficiently in batches, rather than 
individually as they are detected. This lets the device's application processor 
remain in a low-power idle state until batches are delivered.</p>

<p>You can request batched events from any sensor using a standard event listener, 
and you can control the interval at which you receive batches. You can also 
request immediate delivery of events between batch cycles. </p>

<!-- <div style="margin:0 0;width:770px;height">
  <div style="float:right;width:380px;">
<img src="{@docRoot}images/kk-memdinfo.png" alt="" width="360" height="200" style="margin-bottom:0;box-shadow: 3px 10px 12px 1px #eee;border:1px solid #ddd;border-radius: 6px;">
<p class="img-caption" style="padding-top:1.5em;line-height:1.25em;">Real-world power reductions for apps.</p>
</div>

  <div style="width:380px;">
<img src="{@docRoot}images/kk-procstdats.png" alt="" width="360" height="200" style="margin-bottom:0;box-shadow: 3px 10px 18px 1px #eee;border:1px solid #ddd;border-radius: 6px;">
<p class="img-caption" style="padding-top:1.5em;line-height:1.25em;">Step detector power use over time.</p>
</div>

</div>-->










<div style="float:right;margin:1em 2em 0em 5em;width:200px;clear:both">
  <img src="{@docRoot}images/kk-moves-n5.png" alt="" width="240" style="margin-bottom:0;"> 

<p class="img-caption" style="padding-top:1.5em;margin-left:6px;line-height:1.25em;"><a class="external-link" href="https://play.google.com/store/apps/details?id=com.protogeo.moves">Moves</a> <!-- and <a class="external-link" href="https://play.google.com/store/apps/details?id=com.runtastic.android.pedometer.lite">Runtastic Pedometer</a> are using --> is using the hardware step-detector to for reduced power comsumption.</p>
</div> 

<p>Sensor batching is 
ideal for low-power, long-running use-cases such as fitness, location tracking, 
monitoring, and more. It can makes your app more efficient and it lets you track 
sensor events continuously &mdash; even while the screen is off and the system is 
asleep. </p>

<p>Sensor batching is currently available on Nexus 5, and we're working with our 
chipset partners to bring it to more devices as soon as possible. </p>

<h4 id="44-step-detector">Step Detector and Step Counter</h4>

<p><span style="white-space:nowrap;">Android 4.4</span> also adds platform support for two new composite sensors &mdash;  step 
detection and step counter &mdash; that let your app track steps when the user is 
walking, running, or climbing stairs.  These new sensors are implemented in 
hardware for low power consumption.</p>

<p>The step detector analyzes accelerometer input to recognize when the user has 
taken a step, then triggers an event with each step. The step counter tracks the 
total number of steps since the last device reboot and triggers an event with 
each change in the step count. Because the logic and sensor management is built 
into the platform and underlying hardware, you don't need to maintain your own 
detection algorithms in your app. </p>

<p>Step detector and counter sensors are available on Nexus 5, and we're working 
with our chipset partners to bring them to new devices as soon as possible. </p>


<h2 id="44-sms-provider">SMS provider</h2>

<p>If you develop a messaging app that uses SMS or MMS, you can now use a shared 
SMS provider and new APIs to manage your app's message storage and retrieval. 
The new SMS provider and APIs define a standardized interaction model for all 
apps that handle SMS or MMS messages. </p>

<p>Along with the new provider and APIs, <span style="white-space:nowrap;">Android 4.4</span> introduces new semantics for 
receiving messages and writing to the provider. When a message is received, the 
system routes it directly to the user's default messaging app using the new 
<span style ="font-size:11.5px;">SMS_DELIVER</span> intent. Other apps can still listen for incoming messages using the 
<span style ="font-size:11.5px;">SMS_RECEIVED</span> intent. Also, the system now allows only the default app to write 
message data to the provider, although other apps can read at any time.  Apps 
that are not the user's default can still send messages &mdash; the system handles 
writing those messages to the provider on behalf of the app, so that users can 
see them in the default app. </p>

<p>The new provider and semantics help to improve the user's experience when 
multiple messaging apps are installed, and they help you to build new messaging 
features with fully-supported, forward-compatible APIs.</p>

<h2 id="44-beautiful-apps">New ways to build beautiful apps</h2>




<!--
    <div class="framed-nexus5-port-span-5" style="margin-left:0;padding:auto 1em 1em 0;">
      <video class="play-on-hover" autoplay="">
        <source src="{@docRoot}images/home.mp4" type="video/mp4">
        <source src="{@docRoot}images/immdersive.webm" type="video/webm">
        <source src="{@docRoot}images/immerdsive.ogv" type="video/ogg">
      </video>
    </div>
    <div class="figure-caption">
      Home screen...
      <div class="video-instructions">&nbsp;</div>
    </div>

  </div>-->



<div style="float:right;margin:0px 0px 0px 24px;widdth:246px;">
<img src="{@docRoot}images/kk/kk-immersive-pacras-ljpm.jpg" alt="" width="240" style="margin-bottom:0;">
  <img src="{@docRoot}images/kk/kk-immersive-pacras-lgc.png" alt="" width="240" style="margin-bottom:0;">
  <img src="{@docRoot}images/kk/kk-immersive-pacras.png" alt="" width="240" style="margin-bottom:0;">
<p class="img-caption" style="padding-top:1.5em;margin-left:6px;line-height:1.25em;">A new immersive mode lets apps use every pixel on the screen to show content 
and capture touch events.</p>
</div>

<h4 id="44-immersive">Full-screen Immersive mode</h4>

<p>Now your apps can use every pixel on the device screen to showcase your content 
and capture touch events. <span style="white-space:nowrap;">Android 4.4</span> addsa new full-screen immersive mode that 
lets you create full-bleed UIs reaching from edge to edge on phones and tablets, 
hiding all system UI such as the status bar and navigation bar. It's ideal for 
rich visual content such as photos, videos, maps, books, and games.</p>

<p>In the new mode, the system UI stays hidden, even while users are interacting 
with your app or game &mdash; you can capture touch events from anywhere across the 
screen, even areas that would otherwise be occupied by the system bars. This 
gives you a great way to create a larger, richer, more immersive UI in your app 
or game and also reduce visual distraction.</p>

<p>To make sure that users always have easy, consistent access to system UI from 
full-screen immersive mode, <span style="white-space:nowrap;">Android 4.4</span> supports a new gesture &mdash; in immersive 
mode, an edge swipe from the top or bottom of the screen now reveals the system 
UI. </p>

<p>To return to immersive mode, users can touch the screen outside of the bar 
bounds or wait for a short period for the bars to auto-hide. For a consistent 
user experience, the new gesture also works with previous methods of hiding the 
status bar.</p>

<h4 id="44-transitions">Transitions framework for animating scenes</h4>

<p>Most apps structure their flows around several key UI states that expose 
different actions. Many apps also use animation to help users understand their 
progress through those states and the actions available in each. To make it 
easier to create high-quality animations in your app, <span style="white-space:nowrap;">Android 4.4</span> introduces a 
new transitions framework. </p>

<p>The transitions framework lets you define scenes, typically view hierarchies, 
and transitions, which define how to animate or transform the scenes when the 
user enters or exits them. You can use several predefined transition types to 
animate your scenes based on specific properties, such as layout bounds, or 
visibility. There's also an auto-transition type that automatically fades, 
moves, and resizes views during a scene change. In addition, you can define 
custom transitions that animate the properties that matter most to your app, and 
you can plug in your own animation styles if needed. </p>

<p>With the transitions framework you can also animate changes to your UI on the 
fly, without needing to define scenes. For example, you can make a series of 
changes to a view hierarchy and then have the TransitionManager automatically 
run a delayed transition on those changes. </p>


<p>Once you've set up transitions, it's straightforward to invoke them from your 
app. For example, you can call a single method to begin a transition, make 
various changes in your view hierarchy, and on the next frame animations will 
automatically begin that animate the changes you specified. </p>

<div style="float:right;margin:0px 0px 22px 32px;width:340px;">
<img src="{@docRoot}images/kk-home-crop.png" alt="translucent system UI" widtdh="240" style="margin-bottom:0">
<p class="img-caption" style="padding-top:1.5em;line-height:1.25em;margin-bottom:0;">Apps
can use new window styles to request translucent system bars.</p>
</div>

<p>For custom control over the transitions that run between specific scenes in your 
application flow, you can use the TransitionManager. The TransitionManager lets 
you define the relationship between scenes and the transitions that run for 
specific scene changes.</p>
<h4 id="44-translucent-system-ui">Translucent system UI styling</h4>

<p>To help get more impact out of your content, you can now use new window styles and
themes to request translucent system UI, including both the status bar and
navigation bar. To ensure the legibility of navigation bar buttons or status bar
information, subtle gradients is shown behind the system bars. A typical use-case
would be an app that needs to show through to a wallpaper.</p>



<h4 id="44-notification-access">Enhanced notification access</h4>

<p>Notification listener services can now see more information about incoming 
notifications that were constructed using the notification builder APIs. 
Listener services can access a notification's actions as well as new extras 
fields &mdash; text, icon, picture, progress, chronometer, and many others &mdash; to 
extract cleaner information about the notification and present the information 
in a different way.</p>




<div style="float:left;margin:1em 2em 1em 2em;">
<a href=""><img src="{@docRoot}images/kk-chromium-icon.png" alt="" height="160" style="margin-bottom:0em;"></a>
</div>

<h4 id="44-webview">Chromium WebView</h4>
<p><span style="white-space:nowrap;">Android 4.4</span> includes a completely new implementation of WebView that's based on 
<a href="http://www.chromium.org/Home">Chromium</a>. The new Chromium WebView gives 
you the latest in standards support, performance, and compatibility to build and 
display your web-based content.</p>

<p>Chromium WebView provides broad support for HTML5, CSS3, and JavaScript. It 
supports most of the HTML5 features available in Chrome for Android 30. It also 
brings an updated version of the JavaScript Engine (V8) that delivers dramatically 
improved JavaScript performance.</p>

<p stydle="clear:both;">In addition, the new Chromium WebView supports remote debugging using Chrome 
DevTools. For example, you can use Chrome DevTools on your development machine 
to inspect, debug, and analyze your WebView content live on a mobile device. </p>

<p>The new Chromium WebView is included on all compatible devices running 
<span style="white-space:nowrap;">Android 4.4</span> and higher. You can take advantage of the new WebView right away, 
and with minimum modifications to existing apps and content. In most cases, your 
content will migrate to the new implementation seamlessly in most cases. </p>



<h2 id="44-media">New media capabilities</h2>

<h4 id="44-screen-recording">Screen recording</h4>

<p>Now it's easy to create high-quality video of your app, directly from your 
Android device. <span style="white-space:nowrap;">Android 4.4</span> adds support for screen recording and provides a 
<strong>screen recording utility</strong> that lets you capture video as you use the device 
and store it as an MP4 file.  It's a great new way to create walkthroughs and 
tutorials for your app, testing materials, marketing videos, and much more.  </p>

<p>You can record at any device-supported resolution and bitrate you want, and the 
output retains the aspect ratio of the display. By default, the utility selects 
a resolution equal or close to the device's display resolution in the current 
orientation. When you are done recording, you can share the video directly from 
your device or pull the MP4 file to your host computer for post-production.</p>

<p>If your app plays video or other protected content that you don’t want to
  be captured by the screen recorder, you can use
  <span style="font-size:11.5px;font-family:monospace;white-space:nowrap;">SurfaceView.setSecure()</span>
  to mark the content as secure. 

<p>You can access screen recording through the adb tool included in the Android 
SDK,  using the command <span style="font-size:11.5px;font-family:monospace;white-space:nowrap;">adb
shell screenrecord</span>. You can also launch it through the DDMS panel in
Android Studio.</p>

<h4 id="44-adaptive-playback">Resolution switching through adaptive playback</h4>

<p><span style="white-space:nowrap;">Android 4.4</span> brings formal support for adaptive playback into the Android media 
framework. Adaptive playback is an optional feature of video decoders for 
MPEG-DASH and other formats that enables seamless change in resolution during 
playback. The client can start to feed the decoder input video frames of a new 
resolution and the resolution of the output buffers change automatically, and 
without a significant gap.</p>

<p>Resolution switching in <span style="white-space:nowrap;">Android 4.4</span> lets media apps offer a significantly better 
streaming video experience. Apps can check for adaptive playback support at 
runtime using existing APIs and implement resolution-switching using new APIs 
introduced in <span style="white-space:nowrap;">Android 4.4</span>.</p>

<h4 id="44-cenc">Common Encryption for DASH</h4>

<p>Android now supports the Common Encryption (CENC) for MPEG-DASH, providing a 
standard, multiplatform DRM scheme for managing protecting content. Apps can 
take advantage of CENC through Android's modular DRM framework and platform APIs 
for supporting DASH.</p>

<h4 id="44-hls">HTTP Live Streaming</h4>

<p><span style="white-space:nowrap;">Android 4.4</span> updates the platform's HTTP Live Streaming (HLS) support to a 
superset of version 7 of the HLS specification (version 4 of the protocol). See 
the 
<a href="http://tools.ietf.org/html/draft-pantos-http-live-streaming-07" class="external-link">IETF draft</a> for details.</p>

<h4 id="44-audio-tunneling">Audio Tunneling to DSP</h4>

<p>For high-performance, lower-power audio playback, <span style="white-space:nowrap;">Android 4.4</span> adds platform 
support for audio tunneling to a digital signal processor (DSP) in the device 
chipset. With tunneling, audio decoding and output effects are off-loaded to the 
DSP, waking the application processor less often and using less battery. </p>

<p>Audio tunneling can dramatically improve battery life for use-cases such as 
listening to music over a headset with screen off. For example, with audio 
tunneling, Nexus 5 offers a total off-network audio playback time of up to 60 
hours, an increase of over 50% over non-tunneled audio. </p>

<p>Media applications can take advantage of audio tunneling on supported devices 
without needing to modify code. The system applies tunneling to optimize audio 
playback whenever it's available on the device.</p>



<div style="float:right;padding-top:1em;width:372px;margin-left:2em;">

<img src="{@docRoot}images/kk-loudnessEnhancerAnnotated.png" alt="Visualizer showing loudness enhancer audio effect" width="360" height="252" style="border:1px solid #ddd;border-radius: 6px;" />
<p class="img-caption" style="margin-left:6px;line-height:1.25em;">Visualization of how the LoudnessEnhancer effect can make speech content more audible.</p>
</div>

<p>Audio tunneling requires support in the device hardware. Currently audio 
tunneling is available on Nexus 5 and we're working with our chipset partners to 
make it available on more devices as soon as possible.</p>

<h4 id="44-audio-monitoring">Audio monitoring</h4>

<p>Apps can use new monitoring tools in the Visualizer effect to get updates on the 
peak and RMS levels of any currently playing audio on the device. For example, 
you could use this creatively in music visualizers or to implement playback 
metering in a media player. </p>



<h4 id="44-loudness">Loudness enhancer</h4>

<p>Media playback applications can increase the loudness of spoken content by using 
the new LoudnessEnhancer effect, which acts as compressor with time constants 
that are specifically tuned for speech.</p>

<h4 id="44-audio-timestamps">Audio timestamps for improved AV sync</h4>

<p>The audio framework can now report presentation timestamps from the audio output 
HAL to applications, for better audio-video synchronization. Audio timestamps 
let your app determine when a specific audio frame will be (or was) presented 
off-device to the user; you can use the timestamp information to more accurately 
synchronize audio with video frames.</p>

<h4 id="44-miracast">Wi-Fi CERTIFIED Miracast™</h4>

<p><span style="white-space:nowrap;">Android 4.4</span> devices can now be certified to the Wi-Fi Alliance Wi-Fi Display 
Specification as Miracast compatible. To help with testing, a new Wireless 
Display developer option exposes advanced configuration controls and settings 
for Wireless Display certification. You can access the option at <strong>Settings &gt; 
Developer options &gt; Wireless display certification</strong></p>. Nexus 5 is a Miracast certified wireless 
display device. </p>

<h2 id="44-renderscript">RenderScript Compute</h2>

<div style="float:right;padding-top:1em;width:372px;margin-left:2em;">

<img src="{@docRoot}images/kk-rs-chart-versions.png" alt="Renderscipt optimizations chart" width="360" height="252" style="border:1px solid #ddd;border-radius: 6px;" />
<p class="img-caption" style="margin-left:6px;line-height:1.25em;">Performance benchmarks for Android&nbsp;4.4 relative to Android&nbsp;4.3, run on the same devices (Nexus 7, Nexus 10).</p>
</div>

<h4>Ongoing performance improvements</strong></h4>

<p>When your apps use RenderScript, they'll benefit from ongoing performance 
tuning in the RenderScript runtime itself, without the need for recompilation. The
chart at right shows performance gains in Android 4.4 on two popular chipsets.</p>

<h4>GPU acceleration</h4>

<p>Any app using RenderScript on a supported device benefits from 
GPU acceleration, without code changes or recompiling. Since the Nexus 10 
first debuted RenderScript GPU acceleration, various other hardware partners 
have added support. </p>

<p>Now with <span style="white-space:nowrap;">Android 4.4</span>, GPU acceleration is available on the Nexus 5, as well as 
the Nexus 4, Nexus 7 (2013), and Nexus 10, and we're working with our partners 
to bring it to more devices as soon as possible.</p>

<h4 id="44-renderscript-ndk">RenderScript in the Android NDK</h4>

<p>Now you can take advantage of RenderScript directly from your native code.  A 
new C++ API in the Android Native Development Kit (NDK) lets you access the same 
RenderScript functionality available through the framework APIs, including 
script intrinsics, custom kernels, and more. </p>

<p>If you have large, performance-intensive tasks to handle in native code, you can 
perform those tasks using RenderScript and integrate them with your native code. 
RenderScript offers great performance across a wide range of devices, with 
automatic support for multi-core CPUs, GPUs, and other processors. </p>

<p>When you build an app that uses the RenderScript through the NDK, you can 
distribute it to any device running Android 2.2 or or higher, just like with the 
RenderScript support library available for framework APIs.</p>

<h2 id="44-graphics">Graphics</h2>

<h4 id="44-surfaceflinger">GLES2.0 SurfaceFlinger</h4>

<p><span style="white-space:nowrap;">Android 4.4</span> upgrades its SurfaceFlinger from OpenGL ES 1.0 to OpenGL ES 2.0. 
This boosts performance by using multi-texturing, and it improves color 
calibration and supports more advanced special effects.</p>

<h4 id="44-composer">New Hardware Composer support for virtual displays</h4>

<p>The latest version of Android Hardware Composer, HWComposer 1.3, supports 
hardware composition of one virtual display in addition to the primary, external 
(e.g. HDMI) display, and has improved OpenGL ES interoperability. </p>

<h2 id="44-connectivity">New Types of Connectivity</h2>

<h4 id="44-bluetooth">New Bluetooth profiles</h4>

<p><span style="white-space:nowrap;">Android 4.4</span> support for two new Bluetooth profiles to let apps support a broader 
range of low-power and media interactions. <strong>Bluetooth HID over GATT</strong>  (HOGP) 
gives apps a low-latency link with low-power peripheral devices such as mice, 
joysticks, and keyboards. <strong>Bluetooth MAP</strong> lets your apps exchange messages 
with a nearby device, for example an automotive terminal for handsfree use or 
another mobile device. As an <strong>extension to Bluetooth AVRCP 1.3</strong>, users can now set
absolute volume on the system from their Bluetooth devices.</p>

<p>Platform support for HOGP, MAP, and AVRCP is built on the Bluedroid Bluetooth 
stack introduced by Google and Broadcom in Android 4.2. Support is available 
right away on Nexus devices and other Android-compatible devices that offer 
compatible Bluetooth capabilities.</p>

<h4 id="44-ir-blasters">IR Blasters</h4>

<p><span style="white-space:nowrap;">Android 4.4</span> introduces platform support for built-in IR blasters, along with a 
new API and system service that let you create apps to take advantage them. </p>

<p>Using the new API, you can build apps that let users remotely control nearby 
TVs, tuners, switches, and other electronic devices. The API lets your app check 
whether the phone or tablet has an infrared emitter, query it's carrier 
frequencies, and then send infrared signals.</p>

<p>Because the API is standard across Android devices running <span style="white-space:nowrap;">Android 4.4</span> or 
higher, your app can support the broadest possible range of vendors without 
writing custom integration code.</p>

<h4 id="44-wifi-tdls">Wi-Fi TDLS support</h4>

<p><span style="white-space:nowrap;">Android 4.4</span> introduces a seamless way to stream media and other data faster 
between devices already on the same Wi-Fi network by supporting Wi-Fi Tunneled 
Direct Link Setup (TDLS).</p>

<h2 id="44-accessibility">Accessibility</h2>

<h4 id="44-closed-captioning">System-wide settings for closed captioning</h4>

<p><span style="white-space:nowrap;">Android 4.4</span> now supports a better accessibility experience across apps by adding 
system-wide preferences for Closed Captioning. Users can go to <strong>Settings</strong> &gt; 
<strong>Accessibility</strong> &gt; <strong>Captions</strong> to set global captioning preferences, such as 
whether to show captions and what language, text size, and text style to use. </p>

<p>Apps that use video can now access the user's captioning settings and adjust 
their presentation to meet the user's preferences. A new captioning manager API 
lets you check and monitor the user's captioning preferences. The captioning 
manager provides you with the user's preferred captioning state as well as 
preferred locale, scaling factor, and text style. The text style includes 
foreground and background colors, edge properties, and typeface.</p>


<div style="float:right;margin:22px 0px 0px 24px;width:490px;">
  <img src="{@docRoot}images/kk-captions-n5.png" alt="" width="471" style="margin-bottom:0;">
<p class="img-caption" style="padding-top:1.5em;margin-left:6px;line-height:1.25em;width:480px;">Apps can now refer to the user's system-wide captions preferences. An example of the expected display style is shown right in the settings.</p>
</div>

<p>In addition, apps that use VideoView can use a new API to pass a captioning 
stream along with a video stream for rendering. The system automatically handles 
the display of the captions on video frames according to the user's systemwide 
settings. Currently, VideoView supports auto-display of captions in WebVTT 
format only. </p>

<p>All apps that show captions should make sure to check the user's systemwide 
captioning preferences and render captions as closely as possible to those 
preferences. For more insight into how specific combinations of settings should 
look, you can look at a preview of captions in different languages, sizes, and 
styles right in the Settings app. </p>

<h4 id="44-enhanced-apis">Enhanced Accessibility APIs</h4>

<p><span style="white-space:nowrap;">Android 4.4</span> extends the accessibility APIs to support more precise structural 
and semantic description and observation of onscreen elements. With the new 
APIs, developers can improve the quality of accessible feedback by providing 
accessibility services with more information about on-screen elements.</p>

<p>In accessibility nodes, developers can now determine whether a node is a popup,
get it’s input type, and more. You can also use new APIs to work with nodes that
contain grid-like information, such as lists and tables. For example, you can now
specify new supported actions, collection information, live region modes, and
more.</p>

<p>New accessibility events let developers more closely follow the changes that are 
taking place in window content, and they can now listen for changes in the touch 
exploration mode on the device. </p>

<h2 id="44-international-users">Support for international Users</h2>

<h4 id="44-drawable-mirroring">Drawable mirroring for RTL locales</h4>

<p>If your app is targeting users who use RTL scripts, you can use a new API to 
declare that a Drawable should be auto-mirrored when the user's locale setting 
includes an RTL language. </p>

<p>Declaring a Drawable as auto-mirrored helps you prevent duplication of assets in 
your app and reduces the the size of your APK. When you have drawables that are 
the reusable for both LTR and RTL presentations, you can declare the default 
versions as auto-mirrored and then omit those Drawables from your RTL resources. </p>



<div style="float:right;margin:16px 12px 0px 32px;width:260px;clear:both;">
<img src="{@docRoot}images/kk-pseudolocale-rtl.png" alt="" width="260" style="margin-bottom:0;">
<p class="img-caption" style="padding-top:1.5em;line-height:1.25em;">Pseudo-locales make it easier to test your app's localization.</p>
</div>

<p>You can declare various types of Drawables as auto-mirrored in your application 
code, such as bitmap, nine-patch, layer, state list, and other Drawables. You 
can also declare a Drawable as auto-mirrored in your resource files by using a 
new attribute. </p>

<h4 id="44-pseudolocale-rtl">RTL pseudo-locale</h4>



<p>To make it easier to test and debug your layouts, Android includes an RTL 
pseudo-locale as a new developer option. </p>

<p>The RTL pseudo-locale switches the device to RTL layout for all locales and 
displays text in your current language.  This can help you find layout issues 
across your app, without having to display the app in an RTL language.  You can 
access the RTL pseudo-localed as in <strong>Settings &gt; 
Developer  options &gt; Force RTL layout direction</strong>.</p>

<h2 id="44-security">Security enhancements</h2>

<h4 id="44-selinux">SELinux (enforcing mode)</h4>

<p><span style="white-space:nowrap;">Android 4.4</span> updates its SELinux configuration from "permissive" to "enforcing." 
This means potential policy violations within a SELinux domain that has an 
enforcing policy will be blocked.  </p>

<h4 id="44-crytpo">Improved cryptographic algorithms</h4>

<p>Android has improved its security further by adding support for two more 
cryptographic algorithms. Elliptic Curve Digital Signature Algorithm (ECDSA) 
support has been added to the keystore provider improving security of digital 
signing, applicable to scenarios such as signing of an application or a data 
connection. The Scrypt key derivation function is implemented to protect the 
cryptographic keys used for full-disk encryption.</p>

<h4 id="44-other">Other enhancements</h4>

<p>On multiuser devices, VPNs are now applied per user.  This can 
allow a user to route all network traffic through a VPN without affecting 
other users on the device. Also, Android now supports FORTIFY_SOURCE level 2,
and all code is compiled with those protections. FORTIFY_SOURCE has been
enhanced to work with clang.</p>
</ul>

<h2 id="44-tools">Tools for analyzing memory use</h2>

<h4 id="44-procstats">Procstats</h4>

<p>A new tool called <strong>procstats</strong> helps you analyze the memory resources your app 
uses, as well as the resources used by other apps and services running on the 
system. </p>

<p>Procstats keeps track of how apps are running over time, providing data about 
their execution durations and memory use to help determine how efficiently they 
are performing.  This is most important for apps that start services that run in 
the background, since it lets you monitor how long they are running and how much 
RAM they are using while doing so.  Procstats will also collect data for 
foreground applications about memory use over time to determine the overall 
memory profile of the app.</p>

<p>Procstats can help you identify background services started by your app. You can 
keep track of how long those services continue running and how much RAM they use 
while doing so. Procstats also lets you profile your app while it's in the 
foreground, using its memory use over time to determine its overall memory 
profile.</p>




<div style="margin:2em 0em;width:780px;">

  <div style="float:left;width:390px;">
<img src="{@docRoot}images/kk-procstats.png" alt="" width="360" style="margin-bottom:0;box-shadow: 3px 10px 18px 1px #eee;border:1px solid #ddd;border-radius: 6px;">
<p class="img-caption" style="padding-top:1.5em;line-height:1.25em;width:360px;">The new <strong>procstats</strong> tool lets you check the memory use of apps and services over time.</p>
</div>

  <div style="float:right;width:390px;">
<img src="{@docRoot}images/kk-meminfo.png" alt="" width="360" style="margin-bottom:0;box-shadow: 3px 10px 12px 1px #eee;border:1px solid #ddd;border-radius: 6px;">
<p class="img-caption" style="padding-top:1.5em;line-height:1.25em;width:360px;">The enhanced <strong>meminfo</strong> tool lets you see details of memory use for an app.</p>
</div>

</div>


<p style="clear:both;">You can access procstats from the adb tool included in the Android SDK,
  <span style="font-size:11.5px;font-family:monospace;white-space:nowrap;">adb shell dumpsys
  procstats</span>. Also, for on-device profiling, see the Process Stats developer option, below. </p>


<h4 id="44-procstats-ondevice" style="clear:both">On-device memory status and profiling</h4>





<p><span style="white-space:nowrap;">Android 4.4</span> includes a new developer option to make it easier to analyze your 
app's memory profile while it's running on any device or emulator. It's 
especially useful to get a view of how your app uses memory and performs on 
devices with low RAM. You can access the option at <strong>Settings &gt; 
Developer options &gt; Process stats</strong></p>

<div style="float:right;margin:22px 0px 0px 24px;width:490px;">
  <img src="{@docRoot}images/kk-proc-device-overview-tri.png" alt="" width="240" style="margin-bottom:0;">
<img src="{@docRoot}images/kk-proc-device-detail.png" alt="" width="240" style="margin-bottom:0;padding-left:6px;">

<p class="img-caption" style="padding-top:1.5em;margin-left:6px;line-height:1.25em;width:480px;"><strong>Process stats</strong> is a convenient way to check your app's memory use. You can see how your app compares to other apps and zoom in on specific data about your app or it's background services.</p>
</div>


<p>The <strong>Process Stats</strong> option shows you a variety of high-level metrics on your 
app's memory use, based on data collected using the new procstats service.  On 
the main screen you can see a summary of system memory status. Green indicates 
relative amount of time spent with low RAM usage, yellow indicates moderate RAM 
usage, and red indicates high (critical) RAM usage</p>

<p>Below the summary is a list summarizing each app's memory load on the system. 
For each app, a blue bar indicates the relative computed memory load (runtime x 
avg_pss) of its process, and a percentage number indicates the relative amount 
of time spent in the background. You can filter the list to show only 
foreground, background, or cached processes, and you can include or exclude 
system processes. You can also change the duration of the data collected to 3, 
6, 12, or 24 hours, and you can include or exclude uss memory. </p>

<p>To take a closer look at a specific app's memory usage in isolation, tap the 
app. For each app, you can now see a summary of the memory consumed and the 
percentage of the collection interval that the app has been running. You can 
also see the average and maximum usage over the collection period, and below the 
app's services and the percentage of time they've been running. </p>

<p>Analyzing your app using the data in Process Stats can reveal issues and suggest 
possible optimizations for your app. For example, if your app is running longer 
than it should or using too much memory over a period of time, there could be 
bugs in your code that you can resolve to improve your app's performance, 
especially when running on a device with low RAM. </p>

</div><!-- END ANDROID 4.4 -->