Advice on export settings (codecs, sizes, etc.)

Question

I have a 1-minute iMovie, non-HD, 720x480. It was shot with a basic camcorder.
I exported it using the Share > QuickTime > Web preset, and it came out as a 1MB movie, 320x240, and is REALLY grainy and kind of hard to watch.
So I tried to experiment with expert settings, but every expert setting I try multiplies the final file size (typically at least to 20MB or more).
What I'm looking for is "one step up" from the Web preset -- something that's 2-4MB in size, and looks better than my 1MB exported version.
I don't see many details on what the "Web" preset is, except that it's 12fps (I think that's fine -- this isn't sports), and 320x240. Does anyone have any tips or recommendations on other codecs/settings that would produce a better result but at an economical size just slightly larger than the Web preset?
(I'd love it to be larger than 320x240 but when I step up to 640x or 720x I get into 30MB movies...)

Answer 1

Even at 320x240 resolution, the MPEG-4 looks great whereas the H.264 was too blocky and grainy.
That may be due to other factors, not just whether the movie uses the Apple MPEG4 codec or the H.264 code. H.264 is able to deliver beautiful movies, as evidenced by Apple's movie trailers. (Don't expect to achieve that quality without using high-end, high-price software.)
To compare features of two movies you can open both in QuickTime Player, then choose Window > Show Movie Info. Click in the two movie windows in turn to compare their features.
The Movie Info window lets you look at important variables like the Frames Per Second, Data Size and Data Rate of the two movies. These were set by the iMovie export pre-sets used to create the movie.
If the movies aren't exactly what you want, you can use iMovie's Expert Settings export option to configure your own exports using "improved" export settings. You can increase the data rate, for example, to get better quality image. Or lower the window size to improve quality with the same data rate.
The H.264 is a particularly useful codec, delivering great-looking video at very low data rates. How low you can go will depend, in part, on the content of the video. It's often a matter of trial and error.
One strategy is to export with H.264 using a very high data rate so you see what the codec can deliver, then try other exports with lower data rates until the quality is no longer acceptable. When the movie file size achieves your goal, you're done.
Apple's new "Apple TV" export pre-set does a great job using H.264. It doesn't let you control things like the window size, however, at least not from iMovie.
But if you have QuickTime Pro, note that the Apple TV export pre-set automatically exports at the current size of your movie window. So if you want a small-window export, set the movie window to that size before exporting.
Karl