Choosing good video source

The following tips will help you optimize the quality of your video for web delivery:

• - Use a tripod to reduce camera movement. A steady camera reduces the number of pixels that change from frame to frame, giving you better quality at higher compression rates (lower data rates).
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• - Use good lighting techniques. Low-light or light-gain filters produce video noise on the image. This noise is different for each frame of video and makes it difficult for the codec to compress the file at a good quality.
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• - Use the best camera possible. Low-grade cameras-specifically consumer-based ones that record an analog signal on magnetic tape (VHS, Hi-8, and so on) and still digital cameras in movie mode-produce much video analog noise. Even if the camera is on a tripod, with excellent light, it will produce noise.
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• - Whenever possible, always encode a file from its uncompressed form. If you convert a pre-compressed digital video format into the FLV or F4V video format, the previous encoder can introduce video noise. The first compressor has already performed its encoding algorithm on the video and has already reduced its quality, frame size, and rate. It may have also introduced some of its own digital artifacts or noise. This additional noise affects the encoding process and may require a higher data rate to play back a good-quality file.

Frame motion is another factor to consider in your encoding formula. This affects the percentage of the pixels that change from one frame to another. This change can result from a person or object moving, camera effects, or post-production effects, such as the following:

• - Someone walking past the lens, tree leaves blowing in the wind, cars driving by, or an extreme close-up of a face
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• - Camera panning, zooming, or shake from a hand-held camera
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• - Postproduction effects such as dissolves, fades, wipes, or complex video effects
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• - Excessive zooming and rolling (Panning isn't as bad, since most modern encoders use motion vectors to account for linear motion of groups of pixels.)
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• - Auto-focus and auto-exposure features change the value of all of the pixels in an image from one frame to the next.

Finally, Do the best you can with what you have to work with. You do not need to have access to professional equipment, a tripod, and excellent lighting conditions, or eliminate all fast motion in your video. Just remember that the higher the quality of your video source, and the less noise and radical pixel change in that source, the lower the data rate required to render a good playback file.

For more information, visit http://www.adobe.com/devnet/flash/learning_guide/video/part03.html