A question that is often posted to user forums and Adobe’s community help regards what settings to use when encoding video for different types of content.
Without knowing the specifics about a user’s video requirements, such as the desired dimensions of the video and the bandwidth requirements they want to adhere to, it’s difficult to give hard numbers. However, more than likely one of the encoding presets that Adobe Media Encoder ships with will give you the video quality you’re looking for.
When exporting with Adobe Media Encoder, choosing a format (such as F4V for Flash video) automatically makes available a list of associated presets designed for particular delivery scenarios. Selecting a preset, in turn, activates the appropriate options in the various settings tabs (Video, Audio, and so on). In most cases, one of the provided presets matches your output goals.
For those of you creating web sites using Flash video, you will find a table of the F4V and FLV encoding presets at: F4V and FLV encoding presets
In addition, there is a Flash video bitrate calculator developed by Robert Reinhardt to help you determine the optimal bitrate at which to encode Flash video files.
One area of encoding settings that causes confusion is setting the key frame distance (also known as the key frame interval). In general the default value for the key frame distance provides a reasonable level of control when seeking within a video clip. If you select a custom key frame placement value, be aware that the smaller the key frame distance, the larger the file size.
If your footage has a lot of scene changes or rapidly moving motion or animation, then the overall image quality may benefit from a lower key frame distance. In general, a higher key frame distance produces better image quality because data is not wasted describing the areas of an image that remain unchanged from frame to frame.