Poor quality export from imported mp4 screen capture

Question

My video source is an mp4 file created from a screen capture of a unix app running on a PC. Quicktime plays the mp4 file fine (lots of detail, dark blacks, ...), but the resulting movie (Share > Export Movie > HD 720p) is faded. When shown on a large screen, the movie is pixelated and faded (grey blacks, etc.).
I imported the mp4 file into iMovie (File > Import > Movies) with Fit in Frame, Optimize video unchecked, Widescreen (16/9), and 30 fps NTSC.
I have tried various combinations of import and export settings and the above is the best I get.
I'm guessing the import is throwing half the information away (hence the faded appearance). Whatever the cause, is there a way to import mp4 files into iMovie and get the same quality on the export? I tried exporting the entire import and got a file about half the size.

Answer 1

Your description of the problem - a 'comb' effect - sounds as if the "fields" which make up the resultant picture have been put together in reverse.
(..You don't normally see 'interlaced' video in iMovie's playback window - you normally see just a single field of the two, to make the picture clearer and simpler to display..)
[..A video picture's generally made up of two "fields" which each comprise half the number of lines down the screen: one field comprises the odd-numbered lines, and the other the even-numbered ones. Your exported video should be encoded with the lower (2nd) field first ..as described in this Apple document ..and the problem's mentioned here as well..]
However ..you said in your first post that "..I am using a Sony HDR-HC1 and trying to export at the highest possible settings.."
This is an HDV camcorder, and you didn't say if the original footage which you shot was HDV or normal DV. (HDV is recorded differently from normal DV, as it's recorded in a more compressed format, and it has to be automatically 'unscrambled' by Apple's Intermediate Codec while you're importing it into iMovie HD.)
It seems as if somewhere along the chain of importing>editing>exporting, the fields are being reversed, so that you get this jumpiness on replay when QuickTime tries to deliver a "highest quality" interleaved replay of both fields:
Ah ..sudden thought: you mentioned that you exported thro' iDVD: "..I have used iDVD by dropping it into a DVD theme and it seems to work ok, although the playback is a little jumpy, not quite as good I would have expected.."
You may have left the iDVD settings at their default 'NTSC' instead of switching them to PAL.
Check your iDVD Preferences ..that may be the problem.