Re: Designing Menus for Blu-ray
The first thing to recognize is that BD is supposed to be a fundamentally different viewer experience from normal DVD in that the format is predicated on menus that can run concurrently with the film. Whereas the DVD format meant you were either in the menu system or in the content but not in both, BD has been touted as “interactive” in having menus that can be called up at will over the content, which means that the menus are less like a separate artform that commands your full attention when you are in the navigation system and more like a supportive “service menu”-type graphic that overlays the image. As a result, the menus tend to be more utilitarian and less flashy so as not to compete with the film content being displayed under it. While there is still room for artistic expression and creative work, the menus are now a supporting player rather than the star of a separate opening act as it was in DVD. You have to take this into account when designing menus for BD-J, and take advantage of the benefits of the new programming capabilities.
There is also a physical limitation in creating menus in BD-J, and that’s the buffer size for the graphics. In DVD, this was generally never a problem, because the bulk of the menu image was contained in video space, not graphic space. When the player loads a set of graphic elements to be used in a BD-J menu system, there is a limit to the amount of graphics that can be buffered at the same time… it’s roughly equivalent to five HD frames worth of elements (5 x 1920 x1080 pixels). This load of graphics is called an epoch, and anything in a loaded epoch can be instantly accessed by the viewer. If your menu graphics in total take up more space than the buffer can hold, it means some of your menu graphics cannot be loaded at the beginning, and must be swapped into the buffer when needed, which currently takes time. You can divide your menu graphics into multiple epochs, but only one can be loaded at a time, and there is a pause (sometimes a significant one, depending upon the player) when dumping one epoch out of the buffer and loading another into it. Since you generally want your menus to react quickly to the viewer’s remote operations, the general goal is to try to fit all of your menus into one epoch. If you have complex menus or a lot of chapter thumbnails, this can be a challenge.
Anything you can do for DVD menus can be translated pretty much directly to Blu-ray (you can easily do a video background with a graphic subpicture overlay), but if you do that, you aren’t really taking advantage of BD-J’s programming capabilities. From an artistic standpoint, you generally want to make the BD menus more than just a higher-resolution port of the DVD menus, but if you want to do it, you’re basically going to be dumbing down the BD menus so that they are compatible with the DVD format.
Another thing to keep in mind is that HD is higher resolution than SD, which means text can be smaller onscreen and still be legible in Blu-ray. If you are trying to make the menus identical between DVD and BD, then you’re going to have to make the text big enough to read in SD, which isn’t always as elegant and efficient on BD. Again, if you want to take advantage of Blu-ray as a format, you should be doing designs that highlight the strengths of the format –like the higher resolution—rather than limit yourself to the parameters of DVD.
Essentially, you have to realize that menu graphics for BD-J are a lot more like doing web graphics than like doing video graphics, so you have to design the menus to cater to the idea of cutting up your graphics into pieces, playing with scaling and translation of graphic elements, and creating button states, all while keeping a close eye on the buffer usage. Don’t create menus that are full-screen in the graphics layer; if you want full screen, do the majority of it in the video layer as a background and only put the buttons in the graphics layer. If anything, I think one of the common design mistakes is as much to oversimplify the menus as to make them too complex. It is imperative to understand the format’s capabilities enough to be able to optimize the use of BD-J. Don’t just make it look like a higher-resolution version of DVD. And recognize that there is a difference between complex and complicated… the former means depth and richness, while the latter means confusion and frustration, so it is important to find where the line is drawn between them. Remember, the point of menus is to give viewers an easy way to get from one place to another, and hopefully get them in the proper mood for the content.
Hope this helps,
V