This document describes Intel's latest digital video compression software with new performance enhancements. It is for multimedia developers, video producers, Web-site developers, and anyone playing videos from the Web.

• If you're exploring the Web for fun, read this overview and learn more about Indeo^® video interactive version 4.3. You can download the Indeo video interactive version 4.3 driver to play videos from different Web sites.


• If you're a multimedia software developer, video producer, or Web-site developer, be sure to read about the new YUV color formats, performance enhancements, and the single download file for the 4.3 codec.


• The Features section describes all of the features included in Indeo video interactive.

What is Indeo video interactive?
Indeo video is Intel's digital video capture codec (COmpression and DECompression driver). It allows you to play video on systems that support Microsoft Video for Windows* or ActiveMovie*, without adding special hardware. Indeo video interactive version 4.3 is the latest release of Intel video technology for PCs with performance enhancements for the Pentium^® II processor and the Pentium^® Pro processor.

New in Indeo video interactive version 4.3
If you're producing videos, developing Web sites, or writing multimedia software, you can benefit from Indeo video interactive 4.3's new enhancements, including:

• performance enhancements for the Pentium II processor
• performance enhancements for the Pentium Pro processor
• new YUV output color formats
• improved driver integration.

Getting Indeo video drivers
Intel distributes video drivers (codecs) free of charge to all PC users. You can incorporate them into your products royalty-free. The Drivers page at Intel's Indeo video Web site guides you through the process of selecting and installing the version 4.3 codec.

New Features

Performance enhancements for the Pentium II processor. Indeo video interactive version 4.3 includes performance enhancements that take advantage of the new Pentium II processor's increased performance.

Performance enhancements for the Pentium Pro processor. Indeo video interactive version 4.3 includes performance enhancements for the performance of the Pentium Pro processor.

New YUV output color formats. Microsoft's ActiveMovie* and DirectDraw* technologies allow video codecs to pass decompressed video frames directly to the computer's display hardware using YUV color formats.

Indeo video interactive version 4.3 now supports these YUV output color formats. With proper graphics-card and driver support, YUV output color formats may enable more clearly defined colors, sharper image quality, and greatly improved playback performance.

Improved driver integration. The Indeo video interactive version 4.3 codec is a single driver file that supports both Microsoft Video for Windows* and ActiveMovie 1.0.

Other Features Supported by Indeo Video Interactive

Along with the new features offered in version 4.3, Indeo video interactive provides a range of features designed specifically for powerful multimedia application development.

These features fall into three categories:

• Application interactivity
• Visual quality
• Support for software developers.

Each of these categories is important to software developers, and the codec offers features and performance in each category to enable developers to create a new generation of powerful, sophisticated, and exciting PC multimedia and games applications.

Application Interactivity

Indeo video interactive incorporates unique features that make it possible to include video in interactive multimedia applications and games. This challenges the traditional notion of video as necessarily having a fixed size and rectangular shape.

Transparency
For years, the movie and television industries have used the technique of chroma keying (sometimes called blue-screening) to place foreground objects over synthesized backgrounds. The most common example of chroma keying is the TV meteorologist who appears to be standing in front of a wall-sized map, when in fact he or she is merely standing in front of a blue wall.

Chroma key circuitry electronically separates the foreground pixels representing the meteorologist from the blue background pixels, and overlays the meteorologist on an electronically generated weather map.

The Indeo video interactive codec supports this type of transparency. During encoding, a compression application can send information to the codec describing a color (or range of colors) that represent a transparent background (such as the blue wall in the example above, or the blue background in Figure 1).

Indeo video interactive then analyzes each frame and separates the background pixels from the foreground. It then makes the background pixels transparent, encoding only the foreground objects as compressed video.

Figure 1. Foreground Object With Transparency

Indeo video interactive's transparency encoding is flexible, allowing for multiple foreground objects of arbitrary shape. Foreground objects can also move from frame to frame, allowing you to create video sprites, video objects that can be overlaid on other video or bitmap backgrounds.

During playback, foreground objects can be dynamically composited over different backgrounds, as shown in Figure 2. The meteorologist, for example, can appear over different weather maps. On PCs with sufficiently powerful Pentium processors, a foreground object can even appear over another video stream, such as footage of the tornado being reported.

Local Decode
Sometimes an application needs to display only part of a decoded video image. For example, in a game, users might look through the periscope of a submarine, in which case their view would be limited to a small subset of the entire image. Moreover, this subset will change as the video plays, depending on where the periscope is rotated.

In this case, much of the source image does not need to display, and one would rather not waste processor resource decoding it. Indeo video interactive provides this capability through a feature known as local decode.

As illustrated in Figure 3, the playback application can tell Indeo video interactive to decode only a rectangular subregion, called the viewport from the source-video image. You can define the minimum possible size of the local decode viewport during compression, but you can change the display size and location of the viewport dynamically during playback.

Real-time Video Effects
Users can modify the brightness, contrast, and color saturation of Indeo video interactive video files interactively during playback. This makes it possible to simulate different lighting conditions, or to allow them to tailor the appearance of the video playback to suit their particular graphics environment and preferences.

Visual Quality

The new codec provides excellent image quality, rivaling that of hardware-accelerated video technologies. Video files created for playback from double-spin CD-ROM drives can be encoded at 320-by-240 resolution at up to 30 frames per second with outstanding image detail and clarity.

Hybrid Compression Algorithm
The Indeo video interactive codec uses an advanced hybrid wavelet algorithm to create video at a quality level usually associated with hardware-accelerated technologies.

Enhanced Compression Technology
Almost all video codecs use some form of interframe encoding where video frames are compared and the codec attempts to store only the difference between frames. Usually this is based on backward (or unidirectional) prediction: the contents of some frames are predicted, based on the content of previous frames.

Indeo video interactive also uses a more sophisticated interframe encoding technology called bidirectional prediction, where the contents of some frames are predicted based on previous and future frames.

Because a frame can be encoded based on past and future frames, it is sometimes necessary to first decode a future frame in order to decode and display the current frame while the video plays. Therefore, the Indeo video interactive codec sometimes decodes frames in a different order than the order the frames actually display.

These complex encoding and decoding techniques allow the codec to display improved visual quality, particularly in video sequences with fast movement or many rapid scene changes.

Processor Scalability
In the past, when software-only video played on slower processors, the codec could compensate for insufficient processor power only by dropping frames somewhat randomly, often causing the video to jerk unpleasantly.

The Indeo video interactive codec varies the visual quality of the decoded images dynamically, according to the processor power available during playback.

• On more powerful Pentium processor-based systems, Indeo video interactive produces video of quality rivaling hardware-based codecs.
• On lower-end Pentium processor-based systems, the codec scales back the visual quality without dropping entire frames.

Support for Software Developers

Palette Handling
Indeo video provides a flexible mechanism for handling 8-bit video palettes, allowing for both default palette and active palette modes. Indeo video interactive also provides a third mode known as the configurable palette, which allows developers to create a set of custom colors that are reserved for application use. Using Palettes With Indeo Video discusses using palette modes in greater detail.

Video Access Protection
Many multimedia developers are concerned about the illegal distribution of copyrighted material. The Indeo video interactive codec helps prevent the misuse of video clips by using access keys, which are numeric passwords that can be inserted into a video clip during compression. If a clip is encoded with an access key, applications need the key to play that clip.

Key Frame Flexibility
Indeo video interactive supports the use of unrestricted key-frame intervals, allowing for a variety of values:

• 0 Only the first frame in the file is a key frame. No other key frames occur in the file.
• 1 Every frame in the file is a key frame.
• 2, 3, ... n Every nth frame in the file is a key. The value of n has no upper limit.

NOTE: Because Indeo video interactive version 4.3 generates higher quality at lower data rates, the default key frame interval is now 15.

In addition to flexibility in key-frame intervals, Indeo video interactive allows for aperiodic key frames. During editing, the encoding application can tell the Indeo video interactive codec to place a key frame at any location. This allows video producers to specify access points anywhere within a video sequence, or to better control video quality by placing key frames on scene-change boundaries.