About digital video and Flash 283
Select the proper frame rate Frame rate indicates how many frames play each second (fps).
If you have a higher data rate clip, a lower frame rate can improve playback on lower-end
computers. For example, if you are compressing a talking head clip with little motion, cutting
the frame rate in half will probably save you only 20 percent of the data rate. However, if you
are compressing high-motion video, reducing the frame rate has a much greater effect on the
data rate.
Because video looks much better at native frame rates, Macromedia recommends leaving the
frame rate high if your delivery channels and playback platforms allow it. However, if you
need to reduce the frame rate, the best results come from dividing the frame rate by whole
numbers.
Select a frame size that fits your data rate As with the frame rate, the frame size for your
document is important for producing high-quality video. At a given data rate (connection
speed), increasing the frame size results in decreased video quality. When you select the frame
size for your document, you must consider frame rate, source material, and personal
preferences. The following list of common frame sizes (in pixels) can be used as a guideline.
You can experiment to find the best setting for your project.
■ Modem: 160 x 120
■ Dual ISDN: 192 x 144
■ T1/DSL/cable: 320 x 240
Know progressive download times You should know how long it is going to take to
download your video. While your video clip downloads, you might want to have other
content that appears and “disguises” the download. For short clips, you can use the following
formula: Pause = download time – play time + 10% of play time. For example, if your clip is
30 seconds long and it takes one minute to download, you should give your clip a 33-second
buffer (60 seconds – 30 seconds + 3 seconds = 33 seconds).
Use clean video The higher the quality of the original, the better the final result. Although
frame rates and sizes of Internet video are usually smaller than those of television, computer
monitors have much better color fidelity, saturation, sharpness, and resolution than
conventional televisions. Even with a small window, image quality can be more important for
digital video than for standard analog television. Artifacts and noise that would hardly be
noticeable on TV can be quite obvious on a computer screen.
NOTE
If you intend to embed video clips within the SWF file, the frame rate of the video clip
must be the same as that used by the SWF. Using the Advanced Video Encoding
settings in the Video Import wizard, you can encode video using the same frame rate as
the FLA file. For more information, see “About embedding video in a SWF file”
on page 276.
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