Multimedia flow application in Microsoft Windows CE 3.0
Microsoft Corporation
June 2000
Summary: This article discusses multimedia streaming of Windows Media® components based on Microsoft® Windows® CE DirectX Platform Adaptation Kit 1.2 (Different Microsoft Windows versions.
Contents
Overview
Technical Fundamentals
Windows Media Player Control
Windows Media Technologies
Windows Media Formats
Windows Media Features, WINDOWS Media Features
Windows Media Protocols
Windows Media Codecs
DirectShow
Filter Graph Manager
Filters
For more information
Foreword
The digital revolution has brought a storm that consumers have brought a storm. Hundreds of channels brought by the digital cable of the connecting machine top box can be replaced with the original product. The portable digital audio player provides longer music playback time and provides better sound quality than tape players. The fundamental change of consumer electronics is coming from new phenomena and natural evolution. Due to this change, in the near future, PC will no longer be the only knowledge of digital multimedia sources, has been recognized.
Many new consumer goods are accepted by consumers through digital music, movies, television and other multimedia content. Even with the best compression mode (such as Microsoft Windows Media? Audio), the amount of data of multimedia content is still large. For example, the compression ratio is 120kbits / sec, and the digital audio needs to store a four-minute song with 3.6MB. If you store a two-hour movie, the digital video requires 270MB for 300 kbits / sec, 4 KBITS / Sec, the 3.6GB!
Huge media files can be solved by the following two ways:
Download the entire file to the local memory and process the storage data block sequence (local stream) or processes the entire storage file (non-flow). Or download and process a separate data block sequence (network stream). The network stream can also be processed by the media data created by the server without being stored as a separate file.
Send the next related small amount of data requires fast processing and playback work (not all data sets) because multimedia content is a continuous digital data without rugged long-term time coupling. In other words, the sound block of a song or the pixels in the video frame can be independently processed and played, at least when there is enough time, they are separated. This allows an independent data in time groups to be abandoned. These data will be displayed in different times in the independent time sequence in any process in either process by coding, transmitting, and playback. This method of time sequence of this transmit block is temporarily weakened to the data of the client device being streamed. Client devices need enough cache packages to prevent server, network, client interrupt, or create, send, and time correction.
How do Windows CEs suitable for this description through the Windows Media component? Windows CE DirectX Platform Adaptation Kit 1.2 (OR DXPAK) can provide multimedia playback and PC-based streaming capabilities, but there is no more available structural components. These components operate on a high-performance CPU that supports Windows CE (X86, MIPS R4300 and Compatible, And SH4, Available Now With Dxpak 1.1; ARM, STRONARM, AND INTEGER MIPS Planned For DxPak 1.2). The modular design of Windows Media Components for Windows CE allows you to have enough elastic to select those components on your platform. When using Platform Builder to create an operating system image for your hardware, you can decide if you want a special DirectX or user interface component, communication protocol, or file system. This flexibility allows you to install the technology you need to your platform, save space, reduce complexity. Windows CE 3.0 with The DirectX Platform Adaptation Kit 1.2 (or DXPAK) provides a complete solution for developing a kill-level consumer tool or application. The system that provides adequate component sets for digital multimedia devices is full of vitality, powerful real-time operating systems.
Technical Fundamentals
technical foundation
The DirectShow section of Microsoft DirectX provides a basic platform for multimedia services on Windows CE. Many multimedia applications that can be used alone, in fact, many companies are doing this, but this is not the only way out. A communication structure is above DirectShow, making the application developer's work in advance. Their structure meets the following chart: (MultiMedia1.gif)
Figure 1. Communication Structure Based on DirectShow
Communication structure based on DirectShow
The user can see the top layer of the chart is: web browser or other applications. The application can embed the Window Media Player (WMP) control, or you can connect the interface of DirectShow via COM. In both scenarios, DirectShow manages data flow from source to hardware. Drive developers are the most concerned about the underlying. The application developer is required to have: WMP control, WMT and DirectShow.
Windows Media Player Control
As an ActiveX control and other content, there is a web page. The WMP control is a universal tool that can handle local and streaming multimedia files. It supports all mainstream media file formats, including Windows Media format files (ASF, ASX, WMA, WMX, WMV, WVX, WM, And WMX Files), MPEG Format (MPG and MPE Files), and audio formats, for example, MP3, MIDI, WAV, And AIFF, and MultiMedia Format Avi Files. All of these file formats use WMP controls to be flown from the local storage file, and when combined with Microsoft Windows Media technology, it will support operations over the network. DirectX Platform Adaptation Kit 1.2 (OR DXPAK) supports controls for Windows Media Player 6.4.
Placing The WMP Control in A Web Page
Place WMP controls in the web page
Use the Object tag to embed an ActiveX object into a web page. The following example shows how to insert the WMP control using the Object tag.