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Describes Windows Media technologies that can be used to implement a music purchase or subscription service from an online store. In this scenario, the music is downloaded directly to a mobile device. This article also outlines some basic information about how to implement this type of scenario on a mobile device.
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Janet Thomas Microsoft Corporation January 2006
Applies to: Microsoft® Windows Media® DRM 10 for Portable Devices Windows Media Audio Professional (WMA Pro) Codec
Contents
IntroductionMicrosoft® Windows Media® technologies can be used on a mobile device to download music from an online store. The mobile device can be anything from a basic wireless telephone with a data connection to the Internet, to a complex Personal Digital Assistant (PDA) that includes Internet browsing.
To download music, a mobile device must have a data connection to the Internet included with their plan. Then, when the customer initiates a file download, their mobile device establishes a connection with a Web server over the mobile network. When the music is downloaded, it is stored on the mobile device and can be played when the download is complete. If the playback application on the device supports progressive download, it may be able to begin playing the file before the download is complete.
To implement a download service for a mobile device, you need to decide if you will provide your own content or work with a partner. Then you need to consider the bandwidth and the device capabilities so that you can provide your customer with a positive experience downloading and playing music. You will need to specify that the device you are targeting has enough storage, and processing power to play the music. Microsoft licenses porting kits for the Windows Media technologies that can help you successfully apply and test Windows Media technologies on a mobile device. Microsoft also works with a number of partner companies that can help you implement Windows Media technologies.
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TechnologiesMicrosoft® Windows Media® technologies enable the delivery of downloadable digital audio files directly to a user's mobile device. When you use Windows Mobile® 5.0 with Windows Media Player Mobile, the technology for the file format, the codecs, network protocols, device transfer protocols, and digital rights management (DRM) are all built into the system. If you use an alternative platform, and create your own media playback engine and user interface, Microsoft provides porting kits, specifications, and sample code to help you implement Windows Media technologies on your platform.
The following table describes the Windows Media technologies that can be used to enable a mobile device to download and play Windows Media Audio (WMA) files.
| Technology | Description |
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Windows Mobile® 5.0 with Windows Media Player Mobile
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A device platform that can implement the Windows Media technologies mentioned below
| Windows Mobile 5.0 with Windows Media Player Mobile includes all of the necessary Windows Media technologies built into the system, including Windows Media DRM 10, Windows Media codecs, and Windows Media streaming protocols.
If you use an alternative platform, the Windows Media technologies mentioned below can be implemented on your platform.
| Windows Media DRM 10 for Portable Devices
| Digital rights management (DRM) is used to prevent the duplication of protected media content and enable numerous business models for legitimate use of commercial content.
Windows Media DRM 10 For Portable Devices is available as a porting kit from Microsoft. This porting kit contains source code, documentation, and sample applications to help implement support for Windows Media DRM 10 on portable devices.
For more information about licensing this Windows Media technology, see Licensing Chipsets and Devices That Support Windows Media DRM.
| Windows Media Audio (WMA) Professional Codec
| This WMA codec was specifically created to address the requirements of a mobile device. It is used to decode and play WMA files on a mobile device.
The WMA codecs are available either as part of Windows Media Player Mobile or in the Windows Media Components porting kits.
For more information about licensing, see Licensing Windows Media Technologies for Use in Interim Products.
For more information about the porting kit, see Licensing Consumer Electronic Devices That Support Windows Media.
| Media Transfer Protocol (MTP)
| Media Transfer Protocol (MTP) is a protocol designed for portable media devices. The primary purpose of this protocol is to provide a common protocol for exchanging data between a computer and a portable media device without having to write custom drivers for the mobile devices.
For more information about MTP, see Media Transfer Protocol Specification.
| Advanced Systems Format (ASF) File Reader
| ASF is an extensible file format commonly used for digital media content. An ASF file is composed of one or more digital media streams and supports both local playback and data delivery over a wide variety of networks and protocols.
For more information about the Windows Media SDKs, which include support for creating and reading Windows Media content including ASF files, see the Windows Media Developer Center.
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Some of the Windows Media technologies, such as DRM and the WMA codecs, are also used on the server-side. For more information, see Server: Music and Video Download Scenario.
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ImplementationIf you want to deliver downloadable content directly to a mobile device, there are several things to consider before you begin building and testing the playback application for the device. For example:
It isn't always necessary to create your own online music store. There are numerous online content services available. For more information about a content provider in your area, search the Windows Media Service Provider Program Directory.
It is important to consider the bandwidth that will be available to help facilitate the music download. Also consider the storage capacity of the mobile device and the CPU speed so that you know what the mobile device will be able to handle when it comes to maximum file size and complex decompression algorithms.
Once these considerations are addressed, you can begin implementing Windows Media® technologies on the device with the help of Windows Media porting kits, and license agreements. The PlaysForSure logo program will help you with testing your implementation.
ContentIf you would like to build your own online music store, here are a few resources that might help you get started.
The scenario described in this article assumes that your downloadable music is already available from your online store.
Device CapabilitiesFor its size, the basic mobile device is asked to do a lot, and as customers demand more services, the list of functions that a device must perform will increase. It is important to consider how the capabilities of the device are going to affect your customer's download and playback experience.
Consider the following:The CPU on a device must be able to render digital music. Memory and storage on the device must be large enough to store numerous music files. The power required to play the content may adversely shorten battery life.
Mobile service providers can work with the content provider and the mobile device manufacturers to make sure the mobile device meets the minimum requirements and also leaves room for future improvements.
Device Platform and Media PlaybackThe Windows Mobile® 5.0 platform enables you to use all of the Windows Media technologies. You can use Windows Media Player Mobile to playback and manage content on the device, or you can use the programming model to create your own user experience while keeping the same great and reliable media playback experience already built for you. For more information about Windows Mobile 5.0, see the Windows Mobile Home page.
If your device platform does not include Windows Mobile 5.0, you can use the Windows Media porting kits to implement the core Windows Media technologies for your device platform and then create your own media player application on top of those implementations. For more information, see Licensing Consumer Electronic Devices That Support Windows Media.
Another option is to work with a Microsoft® partner to get a device implementation for your device platform. For more information, see Windows Media Partner Center.
Windows Media DRM 10 for Portable DevicesWindows Media DRM 10 for Portable Devices enables a purchase or subscription model for licensing content. With a purchase model, a transaction covers the purchase of specific music and takes place after the content has been selected. Typically, a customer searches, selects, and purchases music tracks with their mobile device. After the transaction is approved, the music and licenses are downloaded. With a subscription model, the license is renewable, if the device contains a secure clock and metering capabilities.
Windows Media DRM 10 for Portable Devices enables playback of protected content on mobile devices using one of these transaction models. For more information about how to license Windows Media DRM 10 for Portable Devices, see the Licensing Windows Media DRM Technologies.
TestingWindows Hardware Quality Labs (WHQL) works with manufacturers to ensure that their hardware is compatible with Microsoft Windows® operating systems. WHQL supports hardware compatibility testing, reviews hardware submissions for the “Designed for Windows” Logo Program for Hardware, and returns digitally signed drivers to the manufacturers that developed the devices and systems. For more information, see WHQL Testing - Overview.
Ensure that your device meets the criteria outlined in the PlaysForSure test kit and then submit your device to a certified PlaysForSure testing center for logo certification. For more information, see PlaysForSure Starter Kit: Process Overview.
For more information about PlaysForSure, see the PlaysForSure Web site.
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For More InformationDevelopers who are looking to include support for Windows Media in their applications should fully review the information about Windows Media Logo Programs on the Microsoft Web site.
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