While menus are about providing access to the content on your disc, timelines are about the content itself, or packaging up the content in playable chunks. Once you create your menus and timelines, you then link them together into the interactive DVD presentation, as discussed in the following navigation section.
Compared to the design and interaction options available with menus, timelines are rather straightforward: one video track, with optional audio and subtitle tracks, and accessible via marked chapter points. But there still are some interesting possibilities for using timelines in unconventional ways.
Timelines have a video track, but they do not have to play video. A timeline can have no video, and still play audio, or display a still image, or display timed subtitles.
For an audio disc, when you want to use the DVD like a supersized CD jukebox, you can play the audio tracks with a blank video display. The advantage of the DVD, besides more music on the disc, is that you can add menus to access the music. You also can lay out and access the music both as chapters along the timeline and as alternate tracks, which can be particularly interesting for switching between different versions of the same piece.
And because it is a shame to totally waste the display, you might want to display a still image with information about the music, or use subtitles for optional informational overlays. Of course, you then can go further with subtitles to create a karaoke disc with song lyrics timed to the music.
For informational presentations, you can create timed slide shows, as discussed later, or display still images with additional information displayed as timed subtitles. Beyond picture slide shows, you can create information presentations with slides—for example, to use for a display at a meeting venue.
Beyond displaying screenshots of a slide presentation, you also can use DVD subtitles to make more flexible presentations that are easier to change and customize. You can simply edit a text file, import it as a new subtitle track, and overlay it on a predesigned background image. You also can prepare alternate versions, such as different languages, and quickly switch between them in different subtitle tracks.
Because subtitles are not restricted to a couple of text lines at the bottom of the screen, you can display full screens of text information. And, since subtitles are actually implemented as a subpicture graphics overlay plane, you also can design subtitle overlays that include both text and graphics elements. Just be aware of the rather severe limitation in the number of colors you can use for subtitles.
To create text subtitles in Encore, you can simply type text directly into the Monitor window, or import a list of timecodes and associated text from a script file. In either case, you can continue to edit the text with the Text tool and the use the Character palette to adjust its look.
When you actually burn the DVD, Encore will render the text into a graphics overlay layer, using the color values defined in the Timeline Color Set to draw the body of the text, plus a stroke outline and anti-aliased area for blending with the background, as shown in Figure 9-12.
To further annotate your videos and present information, you can go beyond text subtitles to create your own graphics images to use as subtitle overlays. As described in Chapter 4, you can then import these using an image script file that defines the timecode range and image filename for each subtitle overlay.
Even though these are still called “subtitles,” they actually are defined as arbitrary image files that can be up to the full size of the video resolution (i.e., 720 x 480 for NTSC). You can use image scripts to create your own text subtitles, of course, editing them with fancy effects in tools such as Adobe Photoshop or Illustrator. You also can mix text and graphics, or use all graphics, for your subtitle overlays, adding logos or illustrations or any other graphics elements. Even better, you can automate such a tool with scripting to generate a set of image files based on new assets or even database entries.
Again, be aware, however, that the subtitle overlay is implemented using the same DVD subpicture overlay mechanism that is also used for menu button highlights, which means that the imported images are restricted to only three different colors. When you import the images, you identify which colors in the imported image should be assigned to the available colors in the Timeline Color Set. In this case, the color set does not define colors used to render text, but instead defines the colors used when displaying the overlay images.
Because DVDs can play video and audio, you also can use them to present slide shows to step through still images, with an accompanying audio track. As usual with DVDs, there are several different approaches to doing this, from preparing the entire show as a video clip in an external application, to arranging the images in an Encore timeline, to using a linked series of menus.
Each approach has different advantages and tradeoffs. Unlike some consumer DVD applications, Encore does not have a built-in slide show generator. Instead, you can roll your own show as you like.
One fundamental choice is whether you want a self-playing slide show, or one that will be manually advanced by the user:
A self-playing slide show automatically steps through a series of slides, typically at a regular interval such as five seconds. These slide shows are implemented in DVDs as a kind of video track (i.e., a timeline in Encore), and therefore can have a soundtrack playing along with the slides. You also can add alternate audio tracks and subtitle tracks synched with the slide show to annotate the slides.
A manual slide show requires the user to explicitly step from one slide to the next. These can be created as a series of menus, typically with Next and Previous buttons. Although each menu can have associated background audio, it will be cut off as you jump from slide to slide.
The user interaction with these slide shows is very different: automatic advance through a timeline (or playlist) using the Previous/Next Chapter buttons to skip, or manual advance through a series of menus, requiring the use of the Left/Right cursor keys. And, as another option, you also can create timed slide shows from linked menus.
One way to show a slide show on a DVD is to prepare the entire presentation as a video clip using a video-editing tool such as Adobe Premiere Pro, and then import it into Encore. This approach gives you complete flexibility in preparing the show, with snazzy transitions between slides, multiple background audio tracks, varied timing and pacing, and even mixing stills and video.
When using this approach, make sure to insert chapter points at the beginning of each slide so that the viewer can conveniently jump between them. It’s also helpful to add an explicit chapter point near the end of the clip so the viewer can jump rapidly to the end and exit the slide show (especially because many users are not familiar with using the Menu button for this purpose).
Similarly, you can create a playlist that includes multiple such slide show clips. In this case, it’s very important to insert a chapter point near the end of each clip so that you can skip to the next clip, although the chapter point will need to be slightly before the actual end of the clip, and there may be a visible pause when skipping between entries in the playlist.
One disadvantage of the video approach is that the slide show is compressed and stored as a motion video clip, and therefore can take more space than a set of still images, especially when it contains fancy transitions and effects.
You also can create a slide show directly in Encore in the Timeline window. First, import a group of images into the Project window (create a new bin to help keep them organized). Then create a new timeline, and drag-and-drop the images into the video track. Encore will prompt for the duration to display the stills, and automatically insert a chapter point at the beginning of each.
You can change the order of the images by dragging one or more of them in the timeline, and change the length of time each is displayed by dragging the end of the clip in the timeline (as also displayed in the Properties palette). While you cannot insert transitions between the clips, the clips do not have to be immediately adjacent to each other, so you can spread them apart slightly to have a period of black between them, or insert another in-between image such as a gray slide, as shown in Figure 9-13.
With both of these timeline-based approaches to automated slide shows, you also can add audio and subtitle tracks to the show.
The primary form of navigation for the viewer, then, is pressing the Next Chapter and Previous Chapter buttons on the remote control. You should also set the Menu button link for the timeline to jump back to an appropriate menu to reselect the slide show or to move on to other content, even though many (if not most) viewers do not use the Menu button.
The only form of feedback during a slide show is the chapter number display on the DVD player, if the viewer is knowledgeable enough to notice it. You also may want to use subtitles to display a summary of information about each image, at least briefly after each is first displayed, or provide alternate subtitle tracks with additional information that is displayed continuously with each image. You can choose to enable the subtitle display in the link to the slide show, or provide it as an option for the user.
You also can create slide shows as a series of linked menus. These can be manual, requiring the user to explicitly step from one slide to the next, or they can be timed, because menus can automatically time out and execute an end action to move to the next menu.
The most straightforward way to set up this kind of slide show is to create a menu template with Next and Back buttons, and a Home button, and then link together a list of these menus with each image as the menu background, as shown in Figure 9-14.
The viewer then can navigate forward and back in the list of images, or jump out of the list with the Home button. You even can create a slide index menu with thumbnails of the slides to use as the home menu.
To help the user navigate through the slide show, have the link for each Next button also highlight the Next button of the new image (and have each Back button highlight the Back button of the previous menu). The user can then just repeatedly press Enter to move forward through the slides, or, after pressing Back once, just continue to press Back to move in reverse.
Another approach, especially if you do not want to have buttons overlaying the images, is to use invisible buttons that autoactivate. Each slide then has three invisible buttons: a center button that is selected by default, and button routings from it for feft and right. When the user presses the corresponding cursor control key, the associated button then autoactivates and jumps to the adjacent slide. (You also can have Up and Down do the same, or jump to a Home menu.)
Of course, you need to explain this invisible interface to the user somehow. This can be as subtle as small left and right arrow overlays on the image.
Another possibility is to use a pop-up interface, in which pressing Up or Down moves to a button that displays a visible highlight to show the interface choices, or even something such as pop-up help text.
Each image menu also can have an associated audio track to play along with the slide. However, you cannot have one seamless audio clip playing under the slide show as with the timeline-based approaches. The audio for each menu can loop if the menu is displayed continuously, or will be cut short when the user moves to the next image menu, which then starts playing its own clip at the beginning. Plan your audio accordingly, perhaps with a slightly different theme for each slide, and certainly not with a strong and loud soundtrack that will create obvious jumps when the user moves between slides.
Because menus can be timed, you also can design menu-based slide shows that will automatically advance if the user takes no action. You can set the display time and loop count for each menu, and the end action if the menu times out. So, a menu can loop forever (playing audio) waiting for the user to do something, or it can loop for a while and then just go silent and freeze. Or you can essentially create a timed slide show in which each menu autoadvances after, say, five or ten seconds, so the user clicks only if he wants to speed up the presentation.
In this way, you can set up the menus to automatically advance from beginning to the end and then repeat, or even to advance backward from the end to the beginning. By setting the appropriate override for the Next and Previous links you can have the slides advance in whatever direction the user last moved.
You also can set up slide shows for use in unattended displays. The first menu can be designed to loop for a few minutes in case a user wants to run the show manually, and then automatically begin playing. All the other menus then can automatically advance after a shorter period. You even can have the user interrupt the automatic advancing by having any manual button press use a different override for the timeout end action to just have the menu jump to itself and continue looping.