m4v
EDGE H.264
64 kbit bit rate
176 ?— 144 resolution
10 or 15fps
Preserve aspect ratio: Letterbox or crop
16kbit, AAC-LC .3gp
Creating a Reference Movie
Because you are creating Wi-Fi and EDGE versions of the same video, you could provide links to each of
these files in your application and leave it up to the user to determine which one to play back. However,
quite obviously, that??™s a weak solution. A much better option is to embed a reference movie that manages
the versioning for you. A reference movie is a movie file that points to other movie files, each of which is at
a different data rate (the EDGE .3gp file, the Wi-Fi .m4v file). When Mobile Safari requests the reference
movie, QuickTime tests each of the movie URLs and determines which version is most appropriate
based on the current network speed. Once a movie URL is found that best passes the tests, then that
movie is sent to iPhone or iPod touch, which is then opened in the movie playback mode.
MakeRefMovie is a free downloadable OS X tool developed by Apple that you can use to create reference
movies. You can add file or URL references from the Movies Add URL menu item, rank their priority
by dragging and dropping them to the appropriate position on the list, and even specify whether or not
the movie is only available on iPhone (and iPod touch) in its Mobility option (see Figure 6-17 ).
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