More complex movies (with effects and
layered video and audio), require more processing time to display
properly. If Adobe Premiere Elements can’t display an area at full
speed and quality, it adds a thin, red line in the time ruler of
the Timeline. To preview one of these areas, you can first
render it.
Rendering processes the layers and effects and saves the resultant
preview into a file, which Adobe Premiere Elements can use each
time you preview that section of the movie. Once rendered, a section
doesn’t require re-rendering, unless changes are made to it. (In
the Timeline, rendered areas are marked with a green line.)
Note: If
you make significant changes to a rendered area, the preview file
is no longer useful, and the green line changes to red. To preview
complex effects at the full frame rate, you’ll have to re-render
the area.