Subtitler:DVD Authoring

Note: This is an advanced feature that requires knowledge about the DVD authoring tool you use.

Subtitling is now often used for multiple targets as a time. You need not only subtitles for the video tape, but also for DVD authoring. After exporting the picture files and the titlelist, you can import them into your DVD authoring system. This part depends on your DVD authoring system. Following a list of instructions for some systems:

But before, we'd like to remind you of some important differences between Video and DVD subtitling. There are some limitations defined by the DVD design that make subtitle authoring a little bit complex.

Video subtitles are directly in the video signal. They use the full color space of the video signal and are therefore also fully antialiased. They are also absolutely frame accurate. However, you will not be able to turn the subtitles off.

DVD subtitles are overlays of the video stream. The user can select a subtitle stream of his language. The frame accuracy depends on the DVD player, it can vary in practice in practice up to 4 frames. Also, the vertical position is not very accurate. If the DVD is 16:9 and the TV-monotor 4:3, the DVD player will letterbox the video stream, but not the subtitles, so part of the subtitle may be in the black.

The overlay is defined by a reduced color system: The subtitle file has four key colors. On most authoring systems, these are white, blue, red and black, but some support also four gray scale values. As one color is the title (mostly black) and one color is the background (mostly white), this leaves you with two colors (red and blue) for either features like border and background rectangle or for a simulation of antialiasing. You cannot have full antialiasing.

The subtitle file can map these four colors to one of 16 palette colors and to an transparency, which is called contrast (0-15). The colors of the palette itself is however defined in the program itself and not by the subtitle file. This means especially that for simulations of antialiasing, you have to edit the palette of the DVD authoring programm manually.

Moral of the story: DVD subtitles cannot be as good as video subtitles and exporting to DVD authoring needs a setup with some experimenting which is not always obvious for the novice user.

TIFF-DVD Export

Subtitler 1.7 proposes a new file format TIFF-DVD. With this format, Subtitler replaces itself the user defined colors and levels with the key colors black, red, blue and white. The colors and levels themselves are exported separately into the authoring files STL Graphic and Sonic Scenarist.

DVD authoring allows only for 4 key colors, so antialiasing is more a kind of simulation. Subtitler tries to use the key colors at their maximum to allow antialiasung with when elements (border, rect) are not used.

Antialiasing can be controlled with the textsoft parameter. Whenever Textsoft is bigger than 0, the program tries to antialias. For best quality, use the native video formats PAL DVD (720 * 756) and the NTSC DVD (720 * 480). These allow to render the fonts directly to the native space, therefore reducing rescale artefacts. You get the best results when you use PAL DVD and NTSC DVD videoformats, with or without antialiasing.

Text Text Soft Border Shadow Box Antialiasing level Key colors
100% 0 0% - 0% 0 Black=Text
100% 1 0% - 0% 2 Black=Text, Red=Text, Blue=Text
100% 0 0% - 100% 0 Black=Text, Blue=Box
100% 1 0% - 100% 1 Black=Text, Red=Text+Box, Blue=Box
100% 0 100% - 0% 0 Black=Text, Blue=Border
100% 1 100% - 0% 1 Black=Text, Red=Text+Boder, Blue=Border
100% - 100% - 100% 0 Black=Text, Red=Border, Blue=Box

You can view the TIFF-DVD image in the Monitor tool, while you option-shift-click on it.
Note: The characters are wider on the display when you use PAL DVD and NTSC DVD (except for NTSC 4:3) and you may need to reduce the text size to fit in the lines of video subtitling.
Note: Shadows are not supported with TIFF-DVD and that Text is always present.

In the STL and the SST files, the colors are mapped to palette colors.

The STL and SST format only allow to define the palette color, but not what RGB color is actually represented by this color. Subtitler adds a comment into the files ("// Palette") so that you can do it by hand. You will have to do it namely if the title is not white, the border not black and for the mixed colors. You can define this color palette once in the preferences in your application so they are reused for each new project.

The levels are translated from percentages (0-100%) to contrast (0-15).