DVD@ccess
By Hal MacLean
A DVD is a fairly interactive medium which you can set up to behave in a number of different ways. However, even the built in interactivity only goes so far - there may come a time when you want to add some enhancements to the functionality and maybe launch a file or open a web page during computer playback.
This is where DVD@ccess comes in. This is a system to add enhanced playback to your disc and has been developed by Apple since the very early days of DVD Studio Pro. All recent Apple computers can make use of DVD@ccess links which you embed in your DVD menus, and DVD@ccess can also be installed on a PC so that your links will open there as well.
To get it to work you only need to do two things - firstly, you specify a folder which contains the additional content that you want to launch and secondly you write the path to the additional content a bit like you do a URL in a web browser.
If you want to launch a web page on the internet then you only need to specify the URL for the page.
A common requirement is to get your computer to open a document when the DVD is playing back - typically a text file, but it could be anything. When the disc is playing and you navigate to a menu that has the DVD@ccess link in it, the computer will launch the default application to handle the file type and open the file from your disc. In the mean time the DVD will carry on in the background. When you stop reading the text file and close the window you will see the DVD playback waiting for you to arrive back!
Pretty neat, but it is not without it’s problems.
First off, it only happens when playing the disc in a computer. No set top players yet include applications to read documents such as .pdf for example. Secondly, whilst it works well on a mac, the experience is far less satisfactory on a PC, plus the PC user *must* install the DVD@ccess software before it stands a chance of working.
This is where it gets a bit tricky - whilst any disc you create that specifies a DVD@ccess link will automatically include the software when you build it, most PC users are suspicious of installing software that they are not familiar with. For the most part, commercial discs with enhanced content make use of the interactual player which many PCs already have got installed, which means as a DVD author you are already on your back foot with DVD@ccess. However, that isn’t to say you shouldn’t persevere - after all, the more that do install it, the easier it will get for us to employ it in the long run, right?
So - how to author your disc…
DVD@ccess works by you embedding a link in a menu OR in a chapter marker. When the user navigates to the menu, or the chapter marker plays the link automatically triggers and the enhanced content plays. Therefore, the thing to do is decide what you want the user experience to be - on the most part you won’t want to trigger a link from a chapter marker as the track will continue playing, and the user will return to the disc after the track has finished - they will have missed the rest of the track! Playing it again will simply launch the link again, and so it will go. If you add the link to a menu then the user can be given an opportunity to return back to the same menu.
In fact, the way to go about this is to create a button on a parent menu that then goes off to a sub-menu with the DVD@ccess link in it. This can then launch the link but ‘time-out’ and go back to the parent menu. The user will activate a menu button, get the enhanced content and then go back to the disc apparently never having left the parent menu. If the user is watching the disc on a set top player then they will of course see the sub-menu, so it is as well to add a message on that which informs the user there is some additional content to see, if they use a computer.
The actual content to launch will need to be linked to from within the DVD Studio Pro interface. To do so you need to remember a couple of important things:
- Firstly, the content needs to be in a folder. If that folder is to appear at the root of the DVD then it also needs to be in a folder, and this ‘parent’ folder is the one to point to in the property inspector;
- Secondly, the link to a file on a DVD has a specific format which needs to be completed exactly. Any change in the path will result in it not working. A Web URL has the standard format of any web URL - http://www.thedomain.com, for example. A file on your disc on the other hand has a URL like this:
file:///discname/foldername/filename.extension
It is crucial to get this exact, and when you build and format your disc you must remember to use the correct name for the disc. If you have a file (called ‘details.pdf’) in a folder called ‘ROM_Content’ that you wish to use on your disc (called MYDISK) then place the folder inside another (call it whatever you like) and point to that from he property inspector. In the URL you write
file:///MYDISK/ROM_Content/details.pdf
You can download the relevant files for this tutorial and open them in DVD Studio Pro to see how I have created the project.
Alternatives to DVD@ccess
There is only one alternative to DVD@ccess if you want to link to files on the DVD itself and that is to use Sonic’s ‘eDVD’ on a PC which utilises the Interactual player. eDVD is also far more sophisticated in what it can do, giving you far more options to create the links you need. Interactual is installed on a far higher number of computers than DVD@ccess, although it will need installing on a Mac before you can use the links. Since most users will be using a PC it may be prudent to cater for them and use eDVD than to persist with DVD@ccess, but ultimately the choice is yours. If you want to link to web based content then you could (and should) check out Intellidisc.
Alex Alexzander wrote a first rate tutorial about eDVD version 3 which you can read and use to evaluate the system. At the time of writing this, eDVD is at v4, although the basic principles of using it are the same between versions.