In the previous article, we discussed digital TV/The Current Situation and Future of the set-top box software architecture, sharing the future development trend and characteristics of the Digital Home software platform (Http://bit.ly/jCvlNs). In this article, we will discuss why android can become one of the Digital Home software platforms in the future; how can we transplant Android, which was originally customized for handheld devices, to the TV/set-top box platform?
1.First, the first question we need to answer is:Why android?
Why?Can Android become a powerful competitor of the Digital Home software platform in the future?
Let's take a look at AndroidIts ownNatural advantages:
- Android is a complete software solution for consuming electronic devices. It includes:
- Linux Kernel;
- Complete middleware, including2D/3D graphics, multimedia frameworks, WebKit, Dalvik virtual machines, etc;
- Robust reusable applicationsProgramFramework and convenienceSDK/ndk development tool.
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- Android is an open-source project:
- Can be customized and transplanted freely. (the risk of fragmentation is not discussed in this article)
- Android is based on apache2.0 license for commercial purposes.
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- The Android ecosystem has been established:
- Google market already has more than 0.2 million Android applications
- MoreActivation of 0.4 million Android devices
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- Android integrates a large number of ARM architecture optimizations. On arm, android can achieve doubled performance and user experience.
In addition to these advantages,The disadvantages of porting android to the TV/set-top box platform are also obvious:
- NoTV/STB-related APIs cause non-standardization of the android TV/STB application framework.
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- Android is not designed for TV/STB and requires a lot of customization, porting, and optimization work.
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- Google has full control over Android, including new performance, architecture and application framework changes, and roadmap. This poses a certain risk to Android manufacturers for customization and porting.
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- Google's official googletv impact on androidtv:
DevelopmentAndroidtv partners need to carefully consider
Androidtv impact:
- CompatibilityGoogletv?
- After googletv is open-source, how can we quickly and efficiently migrate merge to googletv?
- Reusable or notGoogletv's ecosystem?
These are all issues that need to be considered and also risks. As there is a high threshold to become a parttv leading partner and it is still difficult to confirm the time for googletv open source, we recommend that you design and customize the software architecture for partners who want to develop Android TV/Stb, considering the possibility of compatibility with googletv in the future, many customization and porting work is still required even after googletv is open-source.
Figure 1 describes the android versions released by Google for different target devices.
Figure 1 Android version released by Google for different devices
As shown in figure 1Google TV is a branch based on Android. According to Google's latest road map, the main Android line will be transformed into three types of devices: mobile phones, tablets, and TVs.
2.Then, how can weHow about porting android to a TV or set-top box platform? To clarify this problem, first of all, we must clarify what challenges should we face when we port android to a TV or set-top box platform?
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- Challenges1: TV users have a completely different experience for the user interface, graphic performance, and user interaction mode. This includes:
- TV resolution must be at least 720 p/P and frame rate greater than 30 FPS;
- TV's OSD requires 32-bit color depth; Android's default value is 16 bits;
- The TV user interface, including the content on the interface, is organized in a different way than the mobile phone;
- TV users use remote control instead of touch screen;
- Because TV is a big screen device, it has higher performance requirements for 2D/3D graphics and requires hardware acceleration.
- Challenges2: Suitable for the rich multimedia audio and video experience of the screen:
- A more optimized multimedia framework;
- Supports more audio and video file formats and containers;
- Supports more audio/video coding/decoding standards;
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- Challenges3: Integrated DTV/STB function: integrated digital TV protocol stack,
- For exampleDVB-T, DVB-C, ATSC, etc;
- Extended functions for Digital TVsAPI interface;
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- Challenges4: Push app developers to develop Android apps suitable for TV;
- Challenges5. Content Protection
- How to deployCa?
- How to deployDRM?
Next we will discuss how to deal with these five challenges. Due to space limitations, this article will focus on challenges1. In Articles 3 and 4, we will discuss other challenges in turn.
First, we will challenge1. There are two types of problems:
Category 1: graphic image display problems:
- TV resolution must be at least 720 p/P and frame rate greater than 30 FPS;
- TV's OSD requires 32-bit color depth; Android's default value is 16 bits;
- Because TV is a big screen device, it has higher performance requirements for 2D/3D graphics and requires hardware acceleration.
To address these problems, you must modify or integrate at least the following modules, as shown in Figure 2:
Figure 2 modules required to address the first category of challenges 1
Category 2: Issues related to the user interaction mode:
- The TV user interface, including the content on the interface, is organized in a different way than the mobile phone;
- TV users use remote control instead of touch screen;
To address such problemsThe following modules in Android are modified. For details, see Figure 3:
Figure 3 modules required to address the second type of problem in challenge 1
3.The performance of 2D and 3D images is a key aspect of the overall performance of Android TV. In Android, We can optimize skia and surfaceflinger to accelerate the performance of 2D images.
- How to optimizeHow does skia accelerate the full HD 2D experience?
- ReuseA large number of neon Optimizations in skia; or use neon for further optimization;
- ExploitationGPU (OpenGL ES/openvg /...) For the backend of skia
- The hardware decoder is embedded in the image decoder.
Figure 4 illustrates that the above optimization may occur inWhat modules are in the skia architecture?
Figure 4 modules involved in skia Optimization
- How to optimizeSurfaceflinger accelerates 2D?
- InFor versions earlier than android1.6 (donut) (including donut), the "copybit" Hal must be implemented to achieve 2D hardware acceleration.
- In Versions later than Android 1.6, "copybit" is encapsulated into OpenGL ES. Hardware-implemented OpenGL ES 2D API is used to accelerate hardware.
- Android3.0 (honeycomb) adds new functions in 2D, including:
- InSet in androidmanifest. xml
<Android: hardwareaccelerated = "true"> to start hardware acceleration 2D;
- Application developers can control the scope of hardware acceleration, whether it is global or a certainActivity or a view
- UseGPU provides a smoother User Experience
In the next article, we will continue to explore howAndroid is transplanted to the TV/set-top box platform. It also focuses on the comparison between googletv and androidtv.
