Auto PAL/NTSC sub adjustment

[magic144]

can anybody tell me if there is a tool out there that will automatically translate (vertically) subtitle positions between PAL and NTSC frame sizes

ideally, one would have a PAL-ripped .sup file, then run a PAL2NTSC sub converter (insert magic tool name here), to produce a new .sup file with the sub positions auto-adjusted for the NTSC frame size (proportionately)

I tried SubConverter today, since it is the only thing I've ever seen that will allow me to do vertical translation in an existing .sup file, but it only seemed to allow a vertical translation "by eye", without allowing a comparison of the before and after of the relative positions on the PAL original or the NTSC target

also, I seemed to lose some of the bottom of the bitmaps in the post-processed .sup file after I looked at the re-muxed DVD output image (i.e. the descending parts of letters like 'y' and 'g' were truncated for some reason after I moved all the subs up about 70 pixels) - any reason that would have happened? is it because of the overall frame dimension (the yellow rectangle) not being big enough for the actual subs?

cheers for any feedback and info

m

[Mtz]

Try SubtitleCreator.
Formatting > PAL or NTSC.
Tools > Manipulate SUP.

enjoy,
Mtz

[magic144]

sorry, I meant I had tried SubtitleCreator

the built-in profiles don't seem to cater to PAL or NTSC (Profiles->Apply Profiles) - they're just constant (5 of them) - they don't have variants for both

and if you get the yellow box wrong, then try and manipulate existing subtitles to be in it, it truncates whatever's outside of it - plus I've seen some extra random bitmaps along the bottom edge appear in the modified .sup remuxed...

and how do you know exactly how far you should move them to match the original relative screen position for PAL? (or NTSC if converting the other way?)

anyway, is this the only tool that can do this kind of thing?

thanks again

m

[Matthew]

I'm not sure automatic vertical positioning in and of itself is a fullproof solution, for at least 2 reasons:
-The height of the displayed text will differ
-Subtitles are not always at the bottom of the screen (e.g. they may be at the top during the credits).

To get the correct positioning it is possible to do the following:
-Extract bmps from sup
-Resize bmps to 720 x 480|576
-Recreate sup

The downside (apart from effort) is that resizing can reduce the quality. OCR avoids this but it's a pain in the arse.

[jeanl]

Perhaps you can use DVDSubEdit here? Since you're going from PAL to NTSC, you want to move the subpics (if necessary) up toward the middle of the screen. DVDSubEdit allows you to do that using "horizontal borders" which you can adjust. This allows you to move all the subpics that would normally fall outside of the two borders back inside them, and leave the other untouched. It's not exactly what you need because you don't want to move the pixels that are near the top toward the bottom, you just want to move the bottom ones toward the top, but you can still do that.
To calculate how far in your new borders should be, a PAL frame is 576 while an NTSC is 480, the difference is 96 pixels, so the borders should be at least 96 pixels in. You will need to add about 8% of the target screen high for the "Safe area" (because of the TV overscan) to make sure your subs are visible. So I would suggest adding 38 pixels for a total of 134 pixels. You'd then do "apply to all" to apply that to all subpics. But then, you'll have to go and see whether any subpics were moved down by doing that (subpics that were near the top), and undo the change for them (Ctrl-Z).

Also, if your original is PAL, you should make sure to crop all subpics so the background is as small as possible around the text. In some subpic streams, the background occupies the entire screen (but is transparent, of course), while in others, the background is only a small rectangle around the text. In the first case, the large rectangle will correspond to a PAL frame size, which might cause problems if you use it in an NTSC DVD (I've never tried it, but I would avoid that). Cropping will allow you to turn the large background into a small rectangle around the subs. You can do that automatically with DVDSubEdit as well (there's a "Crop" button, and once you've done that, you can "apply to all").

jeanl