iPhone/iPod Frame Sizes
Can the iPhone/iPod Touch handle video sizes other than 640x360 and 320x180? Since the screen size is 480x360, wouldn't it make sense to have a 480x270 option as well? Am I missing something?
Nope...not missing anything. A technical writer for Apple has a web page that lists all the various sizes and recommended sizes...although some of the logic is a bit odd on what the page recommends.
For instance, the screen size of the device is 480x320 and Apple recommends:
"...a size of 480x360 for standard 4:3 aspect images, because that's the smallest 4:3 image that's at least 480 pixels wide. By the same reasoning, a 16:9 widescreen image should be 586x320, because that's the smallest 16:9 image that's at least 320 pixels tall."
This doesn't make sense for either aspect ratio in all the tests we've done (which are substantial). 4:3 video actually seems to work just as well compressed to just 320x240. We saw no discernable quality difference in outputting to the recommended size above...only much bigger file sizes and slower load and startup when accessing video from web sites. Plus, if you use the size above, you'll lose 20 pixels at the top and bottom of your image when the video is at full size (when you tap the device screen to size it up and down).
For 16x9, 480x272 actually seems to work just as well and again, there's virtually no discernable quality difference when you watch the video. Using Apple's 16:9 recommended size will result in losing losing 53 pixels on each side when the video is at full size.
Don't get me wrong, Apple's sizes work fine and look very good, but my point is you can save a crapload of space and have your files startup and play much more quickly from a website by doing them a little smaller. The iPhone and iPod both do an amazing job of enlarging the videos to fill the screen.
Of course, purists out there will compress their videos at 640x480 just because both devices can play it. But it's just a waste of file space and it definitely won't play very quickly or well from a website at that size on the iPhone.
The link above also has a paragraph that reads as follows...(and this is what we've based our sizes on):
...a 4:3 video shows at 427x320 in landscape orientation, and at 320x240 in portrait orientation. A 16:9 video shows at 480x270 in landscape orientation, and at 320x180 in portrait orientation. One of the dimensions is always 480 or 320. The other may be smaller.
In zoomed video mode, the image is expanded to fill the screen in landscape orientation. Images are displayed at 480x320, and cropped as needed. A 4:3 video shows as 480x320, cropped top and bottom, and a 16:9 video shows as 480x320, cropped left and right.
Magnetic Image, Inc.
It is preferable to have both dimensions be divisible by 16 if possible. You can read many articles on why this is, although in some cases tough to tell the quality difference, esp. on a small phone screen. Anyway, 16:9 video 512x288 h.264 is a good option we've been using for iPhones and iPod Touch. We also use the same file for the web, which obviously loads quicker than the next step up... 768x432. If for some reason you don't want to use sizes divisible by 16, the next step is to go your usual divisible by 8 ratios like 640x360.
We use different steps/setups for the Classic iPods, which many people still keep because they had a larger capacity.
Always design with a purpose.
You had mentioned on the phone that your web people couldn't get the x264 file to play in their flash player. I believe they need to actually put the x264 file on a web server and have the web page's flash player call the file from it. There's a security feature in Flash that won't allow videos to play in the flash player from the hard driver.
There are workarounds to this (which escape me at the moment), but we always test our video files from the web server anyway while building a page so we can see how it will load and stream (or pseudo stream if it's a progressive download).
Tell your web guys to try that (if they didn't already). I'll check your compressed file on Monday, but it will probably be late in the day because I have an all day video shoot.
Magnetic Image, Inc.