Android多媒体开发技术浅析

2012.10.14

Android Multimedia Framework

Media Applications

Video Codecs

Audio Codecs Image Codecs

Media API Libraries

Hardware: processors and accelerators

Operating System Multimedia framework

Silicon vendors provide high performance media primitive implementations optimized for their silicon architecture

Media API library implementations re-use optimized primitives across diverse silicon and platformsPortable integration of

Media API libraries into host operating system - if needed

Available across a wide variety of processor architectures and operating systems and tool chains

Physics Engines

Focused on key ‘hotspot’ functions and algorithms

Multimedia Software Stack

”Application Level”Media Application PortabilityApplications programmed using cross-vendor interfaces

“Integration Level”Media Graph PortabilityIntegrate media networks using standard interconnect protocols

“Development Level” Media Component PortabilityDevelop portable media components using low-level media APIs

More media applications available on more platforms for more end-user value!

Component vendors can ship more advanced functionality across more processors. Media silicon vendors reduce costs and time to market

Portable and powerful media processing graphs can flexibly leverage available platform media components

Streaming Media Infrastructure PortabilityOpen, royalty-free standard

IL

DL

AL

OpenMAX defines three holistically designed media open standards to provide complete streaming media infrastructure portability

OpenMAX - Three Layer Solution

Media Multimedia File Path

• Stagefright 的头文件路径如下：frameworks/include/media/stagefright/

• 实现 Stagefright 功能的文件路径如下：frameworks/base/media/libstagefright/

• 实现 Stagefright 播放和录音功能的文件路径如下：frameworks/base/media/libmediaplayerservice/

• 实现录音和音频的文件路径如下：frameworks/base/media/libmedia/

Media recorder state mechine

Idle

Initialezed

Preparing

Prepared

Recording

Released

Error

setAudoSource()/setVideoSource()

setAudoSource()/setVideoSource()

setAudioEncoder()setVideoEncoder()

setOutputFile()setVideoSize()

setVideoFrameRate()setPreviewDisplay()

setOutputFormat()

reset()

reset()

Prepare()

reset()

Start()

reset()/stop()

release()

reset()

Error occurs or an invalid call

Application

• 照相机系统：android.hardware.Camera 

• 实现录音：android.media.MediaRecorder

• 实现播放：android.media.MediaPlayer

Graphics

Skia 是 Google 一个底层的图形、图像、动画、 SVG 、文本等多方面的图形库，是 Android 中图形系统的引擎。

• 图形包的文件路径如下：frameworks/base/graphics/java/android/graphics/

• 实现图形库：android.graphics.*;

Media Scanner

DLNA

DLNA （ DIGITAL LIVING NETWORK ALLIANCE ，数字家庭网络联盟）

• DMS( 数字媒体服务器 )

• DMP( 数字媒体播放器 )

• DMC( 数字媒体控制器 )

• DMD( 数字媒体下载 )

• DMU( 数字媒体上传 )

DLNA 结构图

The More

• 视频电话• 家庭控制系统• 基于多媒体分享社交平台

09/17/12 20

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