You face a tough choice when you want to deliver your QuickTime movies over the web. Part of your audience has a dialup connection and a slow computer and can’t view large movies with high frame rates. They need small, highly compressed movies. The other part of your audience has a fast connection and a fast computer and easily watch higher bit rate videos. They want movies with the highest possible video and audio quality. How do you satisfy both?

With QuickTime, you don’t have to choose--you just use a reference movie. A reference movie contains pointers to alternate data rate movies--that is, multiple versions of the movie designed for downloading at various data rates.

For example, you could create three versions of a movie--a version optimised for 56K dialups, a version for DSL or cable modems, and a version for T1's and higher--put them all on your webpage, and have the reference movie choose which is appropriate for each viewer.

That’s right, QuickTime 3 and later can auto-select the right movie for any connection speed (or CPU speed, or language, or QuickTime version) in the QuickTime Settings dialog without the viewer having to make a choice, and without special coding on your part. You can even create a default movie that plays if none of the criteria are met.

To create a reference movie/alternate data rate movie setup, you’ll need the Pro version of QuickTime Player and an application that allows you to make a reference movie, such as Peter Hoddie's XMLtoRefMovie utility, or Apple’s free MakeRefMovie utility.

Making alternate data rate movies

Creating the alternate data rate movies is a straightforward process.

• Start by creating a master movie of the highest possible quality. That means the largest frame size, the highest frame rate, and the least compression on audio and video tracks. You’ll be making the alternate movies from this master.
• Determine the number of alternate data rate movies you want to create, and the rate for each one. A typical spread for web delivery is one each for 56K (56 Kbits/sec max, but usually much lower), DSL/cable (up to about 128 Kbits/sec), and T1/T3 (up to 1 Mbit/sec). If you are delivering media on CD-ROM, you may want to create a spread for slow computers and fast computers, or for 2X, 8X, and 24X drives.
• Create the alternate data rate movies from the master using the appropriate image dimensions and codecs. You can do this in QuickTime Player using the Export option in the File menu.
• If some of your alternates are streaming movies, make Fast Start movies that point to them, and use the Fast Start movie as the alternate for the stream. To create a Fast Start movie that points to a streaming movie, open the streaming movie in QuickTime Player by choosing Open URL from the File menu and typing in the URL. Then choose Save As from the File menu, name it, and save it as a self-contained movie.
• Also create a default movie that anyone in your audience can see, no matter what connection or computer they are using. It could be a few frames from your movie with a low-bandwidth audio track, or a single image with a scrolling text track and no audio, or just an image. In any case. keep it very small, because the browser will download it even if an alternate movie is used.
• Name each movie in a logical way, including the .mov filename suffix. For example, you may want to name your alternate movies altmov01.mov, altmov02.mov, and altmov03.mov. Save as self-contained movies. Store them all in the same folder or directory.

Making a reference movie

You can make a reference movie for alternate data rates based on connection speed or other criteria using an application such as the free utility program MakeRefMovie, available from Apple for Mac OS 9 , Mac OS X, and Windows. The latest version of MakeRefMovie can also create reference movies that choose among alternate movies based on CPU speed, language, or QuickTime version.

Once you’ve made the alternate movies, follow these steps in MakeRefMovie:

• Open MakeRefMovie.
• Save your new document in the same folder or directory where the alternates are located. Make sure the reference movie filename contains the '.mov' extension. This reference movie will call upon the alternates.
• Drag each of the alternate movies onto the window of MakeRefMovie. An alternate movie will appear for each file you drag-and-drop. Or you can open each file separately by choosing 'Add movie file' from the Movie menu or you can type the URL to your streaming movie by selecting "Add URL" from the Movie menu.
• Set the minimum connection speed for each alternate movie in the Speed: pop-up menu.
• Set the load order of the movies in the Priority: pop-up. For example, you may want the reference movie to call the highest quality movie first, then the medium quality movie, and last the lowest-quality or default movie. If there is more than one movie designed for the same connection speed, set a priority for which movie will load first.
• Specify the default movie by checking Flatten into output. The default movie should be compressed with a codec supported by older versions of QuickTime for backward compatibility. This checkbox can only be applied to one movie.
• Save the reference movie and place it and all the alternate movies in the same directory. Upload the directory or folder to the server.
• If you are putting the movies on a webpage, embed the reference movie into the HTML using the <OBJECT> tag. The reference movie will load the appropriate alternate based on the viewer’s connection speed. More about embedding QuickTime movies into webpages using HTML.