Local Decode

Question: What are the differences between Indeo® video interactive and Indeo video Release 3.2?

The main differences are higher quality video, processor scalability, and new features designed for interactive multimedia applications. Indeo video interactive software uses a completely new compression algorithm, including advantageous features such as bidirectional prediction, to yield better image quality than Release 3.2, comparable to software MPEG. Indeo video interactive also encodes data at lower rates than Release 3.2, so more video of a given quality can fit onto a CD­ROM. Indeo video interactive also allows image quality to scale according to the processor power available. Finally, Indeo video interactive supports the development of interactive multimedia applications with features unavailable in Release 3.2. You can specify that portions of a video frame be rendered as transparent, or that only a portion of the frame be decoded. Users can change the brightness, contrast, and saturation of video files during playback. Key frames can be placed wherever they are needed, at arbitrary intervals. And video files can be protected from unauthorized access.

Question: What is local decode?

Local decode allows programmers to create an independent video display--a view rectangle--within a larger video frame. This allows you to simulate branching or give end users the ability to pan within a scene.

Question: What are the requirements for compressing with local decode?

You must specify the minimum viewport size when you compress the video. The smallest permissible viewport size is 64 by 64. If you're not using local window decode, leave the viewport size at zero.

Question: What are the requirements for playback using local decode?

You can change the position of the viewport only at key frames. You can make the viewport smaller but not larger until the next key frame.

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