Instruction manual

HDE-3000 - 85 -
Appendix C. Discussion of HD Time Code
Definitions
SD = standard definition video (NTSC and PAL).
HD = high definition video (1080i, 1080PsF, 1080P, and 720P).
FPS = frames per second.
Introduction
In the past, subtitle/caption authors only had to contend with two video standards (NTSC
and PAL) and three time code frame rates (NTSC non-drop frame, NTSC drop frame, and
PAL). Now for HD video, there are more video standards and more time code frame rates to
manage. This results in time code issues that authors have to deal with in order to author
subtitles and captions for HD video. The HDE-3000 compensates for several of these
issues, but authors must be aware of what the HDE-3000 can and can’t compensate for.
The HDE-3000 will always encode syntactically correct subtitle/caption jobs, but if there are
time code problems then the captions/subtitles will not be encoded at the correct times.
The Importance of Time Code
Time code provides the time source required for “offline” (post production)
subtitle/caption authoring. The authoring systems produce the information to be encoded
with reference to the time codes associated with the video. As it has always been for offline
authoring, if the time code gets altered between the authoring and encoding processes (re-
striped, frame rate converted, etc.) then the timing of the subtitles/captions will be encoded
improperly.
With the array of HD format conversion features available on many pieces of HD video
equipment, the chances of the time code being altered between the authoring and encoding
processes is greatly increased. Extra care must be observed to insure the integrity of the
time code during the subtitling/captioning process.