AnimEigo: The AnimEigo Titling System

If the program needed to change the subtitle at frame “X”, it would instead wait until frame “X-1”, wait a little longer to give the video beam a head-start, and then follow behind it changing pixels in the screen buffer. Since 1 color had to be used for the “transparent” color that let the background video through, and 1 color was needed as a dark “surround” to make the subtitles visible against any background, this meant that only two colors of subtitles could be visible at any one time. Another problem we had was that what with all the moving around of frame buffers, the Mac would often get so bogged down that it didn’t have time to draw all the subtitles before they were needed, and if there was a sequence with a lot of titles in a short period of time, titles would start coming on late.

Source: www.animeigo.com