How PowerPoint 2003 Plays Multimedia Files in a Presentation

  • Article

 

Andrew May
Microsoft Corporation

April 2004

Applies to:
    Microsoft® Office PowerPoint® 2003
    Microsoft PowerPoint 2002

Summary: Learn how Microsoft Office PowerPoint 2003 and Microsoft PowerPoint 2002 employ Microsoft Windows multimedia technology to play media files, and the best practices to help ensure that the movies and sounds you add to your presentation play as intended. (7 printed pages)

Contents

Introduction
How PowerPoint Plays Media Files
How Codecs Affect Media File Playback
Recommendations for Media Support of PowerPoint Presentations
Package for CD and Media File Support
Conclusion

Introduction

One of the strengths of Microsoft® Office PowerPoint® 2003 and Microsoft PowerPoint 2002 is that users can incorporate sounds and movies to create multimedia presentations that have impact. Understanding how PowerPoint handles media files, and the best ways to help ensure movies and sounds play correctly during your presentation, is vital to creating the most robust, effective multimedia experience for your viewers.

In this article, we examine how PowerPoint handles media files, the three media technologies it employs to determine information about them and to play them, and the factors that influence how the files perform during your presentation.

How PowerPoint Plays Media Files

The PowerPoint application itself does not play media files. Rather, PowerPoint employs three Microsoft multimedia technologies when handling media files:

  • Media Control Interface (MCI) is the default media player that is installed as part of the Microsoft Windows® operating system.
  • Microsoft Windows Media Player is a full-featured, stand-alone media player that you can install as part of the Windows operating system or download separately.
  • Microsoft DirectShow® is a multimedia API built on Microsoft DirectX® technology.

When PowerPoint needs to play a media file, for example as part of a slide build or when a user clicks on the file, it examines the file to determine which media player application is best suited for playing. Because MCI installs as part of the Windows operating system, if PowerPoint determines that it can play the file using MCI, then it uses MCI. If not, PowerPoint attempts to play the file using Windows Media Player. If the file is not compatible with either player, PowerPoint simply does not play the file. PowerPoint uses the DirectShow technology to gather file information to determine which player is appropriate.

PowerPoint selects the appropriate player per file on a case-by-case basis. PowerPoint may use different players to play files in the same presentation. The media player applications, and versions of the applications installed, also affects which player PowerPoint selects. An obvious example of this is whether or not Windows Media Player is installed on the user's computer. For the most robust media file support, it is recommended that you download and install the most recent versions of Windows Media Player and DirectX on every computer on which you plan to give presentations.

There is no way to set which application you prefer PowerPoint to use to open media files, either at the file or application level.

The two diagrams below illustrate the decision logic PowerPoint performs when determining which player to use for a specified media file. The first diagram illustrates the process with audio files; the second, video files.

Figure 1. PowerPoint determination of media player to use with audio files

The following information affects the choice of media player for audio files:

  • Some versions of MCI cannot open files where the file path is greater than 243 characters long.
  • MCI has more robust handling of .midi files.
  • MCI does not support playing playlist files, such as .asx or .m3u.
  • Because the MCI application was developed using DirectX technology, in most cases it can play whatever audio formats the DirectX MediaDet can open.

Figure 2. PowerPoint determination of media player to use with video files

Note   Because the MCI application was developed using DirectX technology, in most cases it can play whatever audio formats the DirectX MediaDet can open.

How Codecs Affect Media File Playback

You may have noticed that the diagram for video files mentions codecs. Codecs are one reason that playing media files can be problematic, so they warrant discussion here.

Codecs (the term is a concatenation of "COmpressor/DECompressor") compress a media file during file creation, and decompresses the file during playback. Codecs are essential for rendering media files, especially video files, small enough for storage on hard disk. However, the codec used to compress a specific file must also be available to decompress the file during playback. If the necessary codec is not installed on the computer opening the file, the file cannot be accessed.

Note that you can use different codecs to encode different files with the same file extension. For example, there are multiple codecs that enable you to create .avi files. A file can also use one CODEC for video, and another for audio. However, to play back files, you still need the specific codecs used to encode the file. On a practical level, this means it is not enough to know that MCI or Windows Media Player supports files with a certain extension; it must also have the required codec installed. For example, just because one .avi file plays on a specified computer does not mean all .avi files will play, if they were encoded using different codecs.

Each media file includes information concerning the codec used to encode it in the file header. Each codec that is registered with Microsoft is designated by a unique four-character code, commonly called a FOURCC. FOURCCs are registered with Microsoft by vendors of the respective multimedia software technologies. FOURCCs are not versioned; each new version of a codec receives its own unique FOURCC designation. For example, the Windows Media Video 8 codec's FOURCC is MV2, while the Windows Media Video 9 codec's FOURCC is WMV3.

For a list of the FOURCCs registered as of June 2003, see Registered FOURCC Codes and WAVE Formats.

When you open a media file in Windows Media Player, Windows Media Player accesses the header information, including the FOURCC code. If a necessary codec is not installed on your computer, Windows Media Player attempts to download and install it automatically. For Windows Media Player to download a codec, it must be available for free, and support auto-downloading. Playing a media file in Windows Media Player and having it automatically download the needed codec(s) is often easier than installing the codec(s) yourself.

As a general best practice, use only established and freely-available codecs to encode your files whenever possible. This increases the chances that the media files plays if you take the presentation to another computer. If you must use a media file created with an old or uncommon codec, it may be easiest to convert the file to another, more widely used codec format to ensure compatibility. You can convert files to more common formats using Windows Movie Maker or similar programs.

Also, be aware that some commercial vendors sell their codecs. If you use a codec that is not free to create media files, you then must license the codec for each computer on which you want to run the presentation. This may be true even of codecs included in video and audio creation applications.

Because it does not directly handle media files, PowerPoint does not provide tools for managing codecs on your computer.

To determine which codecs are installed on a computer using the user interface

  1. On the Start menu, click Control Panel.
  2. Click Sound and Audio Devices, and then click the Hardware tab.
  3. In the Devices list, select either Audio Codecs or Video Codecs, and click Properties.
  4. Click the Properties tab to display a list of the codecs of that type.
  5. To determine the codec a media file uses, right-click the file in the Explorer window, click Properties, and then click the Summary tab.

Recommendations for Media Support of PowerPoint Presentations

To ensure the best support of media files in PowerPoint, we highly recommend you download the latest versions of the media technologies PowerPoint uses, and install them on every computer on which you want to run PowerPoint presentations:

  • DirectX
  • Windows Media Player

In addition, we recommend you make sure the drivers for the video and sound cards on your computer are the latest versions available, as these can greatly impact media file playback.

**Note   **Starting with Windows Media Player 9, Microsoft retired several older, obsolete codecs for security reasons. Once you install Media Player 9, you cannot play any media files that use these codecs. In such a case, the best practice is to re-encode the files using a current, secure codec.

Package for CD and Media File Support

The PowerPoint Package for CD feature provides a convenient way to gather a presentation and all its linked files automatically, either for burning to a CD or storage in a single location. This eliminates the problem of linked files not being available when a user moves the presentation to another computer. Be aware that the Package for CD feature does not package support files, such as any of the media players or codecs needed to play media files, with the presentation.

Conclusion

There are several things you can do to ensure the media in your presentations perform as expected:

  • Install the latest versions of Windows Media Player and DirectX on all computers on which you plan to run your presentations.
  • Update the video and sound card drivers on all computers on which you plan to run your presentations, as necessary.
  • Ensure that the computers on which you plan to run your presentations have the codecs necessary to decode and play the media files included in your presentation. If not, install the necessary codecs or re-encode your media files using codecs that are installed on the computers. Remember, if you open the media file in Windows Media Player, the player attempts to download and install the necessary codec(s) for you automatically.

For information on how to add media files to your presentation as objects that PowerPoint recognizes as movies and sounds, and the advantages of doing so, see Adding Multimedia to a PowerPoint 2003 Presentation.