Features

You can achieve professional results when authoring DVDs at home for less than the cost of a restaurant meal for two. Here we reveal the professionals' secrets and explain the concepts behind creating a sophisticated DVD menu. Together with the right software and our tutorial you'll quickly create DVD projects that stand out from the usual home-made fare.

We've used Sony DVD Architect Studio, which is packed with advanced features and costs just £25 including VAT. This month's cover disc also includes a fully functional 30-day trial of the software.

Dissecting the DVD

Menus in commercial DVDs often seem highly complex, but hardware DVD players are simple devices that are capable of only three basic tasks: showing a video stream (or still image), overlaying a static, block-colour bitmap on top, and playing an audio soundtrack.

The bitmap is used for button highlights in menus and for subtitles in the videos, which on a DVD-Video are known as titles. In fact, there's not much difference between a menu and a title. Menus often comprise a video file - which is how animated menus are created - and titles can include buttons, although this feature is rarely used on commercial discs or supported in non-commercial software.

Video is always encoded in MPEG2 format in either PAL or NTSC video standards, which keeps things simple for the players. The audio requirements are more flexible, and can be in uncompressed PCM (similar to a Wav file), Dolby Digital or MPEG1 Audio Layer II (MP2) format.

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Some players support DTS soundtracks, but if it's used it must be in addition to one of the three standard formats to maintain full compatibility.

The overlay image used for subtitles and button highlights is essentially a four-colour static bitmap. These four colours can be picked from a 24-bit colour palette but are fixed for the duration of a menu or title. Four block colours aren't the prettiest things to look at, but each one can be given a level of transparency.

This is how DVD-authoring software achieves what appear to be animated buttons: the animation is built into the background video file, and the semi-transparent highlight shows which button is selected while letting the animated background shine through it.

It's common for one of the four colours to be fully transparent. Otherwise, you'll be limited to rectangular-shaped highlights, which won't look very exciting. It's also common practice to select just one colour as your highlight and let the software use the remaining two to soften the edges of the highlighted areas by using the same colour you selected but with varying degrees of transparency. However, some DVD-authoring software allows the user to define all four colours independently, which makes various different tricks possible.

Here are the highlights

We said that the four colours are fixed for each menu or title, but this isn't quite true. When you navigate around a DVD menu, you've probably noticed that, after selecting a button by pressing Enter on your remote control, the highlight changes colour for the second or so that it takes to load the selected menu or title. Sure enough, some DVD-authoring software lets you define an additional four colours for activated buttons. Some also let you define yet another four colours for non-highlighted buttons. This feature is rarely used, probably because adding a splash of colour to both highlighted and non-highlighted buttons can cause confusion during menu browsing. However, as our tutorial below shows, it's possible to misuse this feature to create full-colour, animated button highlights.