File Formats—The Final Payoff
The iPod can play slide
shows saved in the MPEG-4 format.
When choosing a slide show application, one of the key features to look for are the output formats that it supports. These determine how you can distribute a show and how your audience can view it. Ideally you'll be able to save versions that can be posted on the Web, e-mailed to friends, played on an iPod or burned to a DVD. If the output format has been around awhile and is widely supported, the viewer will already be a part of any up-to-date browser or available on newer systems. New or up-and-coming formats usually require a separate player or plug-in that a first-time user has to install. Here are the formats you are most likely to encounter.
- MPEG (Moving Picture Experts Group) is a standard for a variety of compression formats. MPEG-1 is used for Video CD and the popular MP3 audio compression format. MPEG-2 is used for broadcast-quality television, digital television and DVDs. MPEG-3 was originally designed for HDTV but was then abandoned (don't confuse with MP3).
The latest version, MPEG-4, is the first version designed for the digital workflow— capturing, authoring, encoding, editing, distributing and playback. This format supports Digital Rights Management, HD-DVD and Blu-Ray discs and is playable on most devices including Quicktime players, cell phones, Apple's iPod, Sony's PSP and Pocket PCs. MPEG-4's goal is "author once, play anywhere."
- QuickTime (.MOV) is a multimedia framework developed by Apple. This format and MPEG-4 are closely related.
- Flash Video (FLV) files can be e-mailed or posted on the Web and viewed using Adobe's Flash Player. This format is supported by YouTube, Google Video, Reuters.com and MySpace. A non-video version, Flash (SWF) is a related format used for animated vector graphics on the web.
- Adobe PDF (PDF) files can be viewed as slide shows on any system that
has the free Acrobat Reader 5.1 or later installed.
- PowerPoint (PPT) presentations can be viewed by anyone who has PowerPoint or the free PowerPoint viewer on their system. Apple's Keynote has its own file format that can be read on other Macs. The free Impess application from OpenOffice.org can export presentations to Adobe's Flash (SWF) and PDF files and open and save PowerPoint files.
- EXE files are programs that contain both the images and the software needed
to view them. Since EXE files can be used to transmit viruses, they won't pass through some firewalls or other security gateways on the Internet and some users are rightfully leery about running them.
- Motion JPEG (M-JPEG) treats each frame in a movie as a JPEG image. Once widely used in camera movie modes, it's been replaced by MPEG-4.
- WMV (Windows Media Video) is used to distribute video on the Internet and on standard DVDs using a variant called WMV HD. WMV HD content can be played back on computers or compatible DVD players.
- AVI (Audio Video Interleave), introduced by Microsoft is considered outdated
but the format remains popular because of its compatibility with existing video editing and playback software and Windows Media Player.