Text that looks good on your computer screen as you are creating it can sometimes look bad when viewed in a final output movie. These differences can arise from the device used to view the movie or from the compression scheme used to encode the movie. The same is true for other vector graphics, such as shapes in shape layers. Keep the following in mind as you create and animate text and vector graphics for video:

• You should always preview your movie on the same sort of device that your audience will use to view it, such as an NTSC video monitor. (See Preview on an external video monitor.)

• Avoid sharp color transitions, especially from one highly saturated color to its complementary color. Sharp color transitions are difficult for many compression schemes—such as those used by MPEG and JPEG standards—to encode. This can cause visual noise near sharp transitions. For analog television, the same sharp transitions can cause spikes outside the allowed range for the signal, also causing noise.

• Avoid thin horizontal elements, which can vanish from the frame if they happen to be on an even scan line during an odd field, or vice versa. The height of the horizontal bar in a capital H, for example, should be three pixels or greater. You can thicken horizontal elements by increasing font size, using a bold (or faux bold) style, or applying a stroke. (See Formatting characters.)

• When animating text to move vertically—for scrolling credits, for example—move the text vertically at a rate in pixels per second that is an even multiple of the field rate for the interlaced video format. This prevents a kind of twitter that can come from the text movement being out of phase with the scan lines. For NTSC, good values include 0, 119.88, and 239.76 pixels per second; for PAL, good values include 0, 100, and 200 pixels per second.

  Apply the Autoscroll - Vertical animation preset in the Behaviors category to quickly create a vertical text crawl.

Fortunately, many problems with text in video and compressed movie formats can be solved with one simple technique: Apply Fast Blur to the text layer, with a Blurriness setting between 1 and 2. A slight blur can soften color transitions and cause thin horizontal elements to expand.