Subtitles out of sync (only 1 frame early or late at random)

[Pedrober]

I would like to know if subtitling streams produced by Subtitle Creator are always precise to the exact frame. I am referring to the .SUP resulting files because simulations are OK with the subtitles showing and hiding at the right time code. But, in the resulting DVD, some subtitles (not many) are 1 frame (or 2) early or late. Please note that this delay is not always the same in a stream: a subtitle can be 1 frame early and another one 2 frames early for no apparent reason. So, if I correct the time code for the whole stream, there are always some subtitles out of sync. As everyone knows, if a subtitle is on or off a frame before a change of shot, the editing becomes more visible (and less professional).
Pedrober

[PINOBIRD]

1 Frame is 1/25 second can you notice that when playing a DVD?

[Pedrober]

Obviously, a standard viewer doesn't perceive it but professional subtitling requires perfect match with editing.
Pedro Bermúdez

[Abond]

What you are using to author the DVD?
Anyway, I can guess, it is something that accept .SUP files for authoring.
Come on, Pedro, are you really thinking that the PROFESSIONALS are using Subtitle creator and .sup files?!?

[Pedrober]

Abond, my main interest was to know if subtitling streams produced by Subtitle Creator are precise to the exact frame. Maybe that degree of precision is beyond the goals of the program.
Pedro Bermúdez

[Matthew]

If I recall correctly DVDSupHtml.exe, included with DVDSupTools, will dump information about each subpicture in a SUP, including the time codes. Perhaps that may be of assistance in judging accuracy.

[Pedrober]

Very useful tool! After testing the .SUP file I have confirmed the lack of accuracy. In general, Subtitle Creator produces a subtitles stream where every subtitle enters 1 frame before the right time code and hides 1 frame late. But it's not always that way. I'll give only a few examples:
#94
00:09:38:16 --> 00:09:41:08 (original time code listing)
[00:09:38:15] - [00:09:41:09] (real position, as explained)
#95
00:09:41:15 --> 00:09:43:08 (original)
[00:09:41:14] - [00:09:43:08] (real position, it shows 1 frame before but it hides at the right point)
#96
00:10:02:10 --> 00:10:05:16 (original)
[00:10:02:09] - [00:10:05:17] (real position, as explained)

00:37:07:17 --> 00:37:10:21
[00:37:07:16] - [00:37:10:22]

00:37:12:08 --> 00:37:16:15 (original TC)
[00:37:12:07] - [00:37:16:17] (real position, but in this case it hides two frames late, not one)

00:37:17:23 --> 00:37:21:20
[00:37:17:22] - [00:37:21:21]

I suppose the problem is due to Subtitle Creator, not to the authoring tool (IfoEdit v.096). Any comments?
Pedro Bermúdez