Levels and Profiles define what settings are possible more than the quality of the export. So long as you have the correct settings available, you shouldn't need to worry about the Level. The problem exports are more likely the result of incorrect settings.
Jim: what would I have messed up here on the settings? Let's ignore the other cases and just focus on .mp4. I double check just before this post: exported two .mp4 files. The only change I made to the settings on the second export (different from the first) was the level and the file name. If it was a settings issue I would have expected both files to have the same issue, or not.
What are your sequence settings? Export settings?
Ok - good call to check the settings more closely. I expanded the settings window vertically and noticed that when I switch between level 4.0 and 4.1 PP changes other settings automatically. Anyway, once I corrected those settings, the level 4.0 version has the same issue as 4.1, so it isn't a level issue. I posted the sequence settings and export settings for a .mp4 file below for review.
I noticed that if I downscale to 1280x720, still keep it upper first interlaced and 29.97fps, the export has the same issue. However, changing to 59.94fps alleviates the issue. I realize a 720i, 59.94 isn't really a common format, but perhaps this export will tell us something. I could not test a 1920x1080i, 59.94 - PP would not allow me to enter those settings.
- Original 1920x1080i, 29.97 .mts clip plays fine.
- H.264 .mp4, DNxHD, Matrox I-Frame all exiting the interlaced combing artifacts on plabyack on the PC, but not the PS3.
- H.264 Blu-ray .m2t and MPEG2 look ok on PC. Here are export settings and sequence settings:
Any interlaced exports are likely to display those artifacts when viewed on a computer screen, which can only display progressive signals. If the goal is computer playback, export out a progressive format. For TV, Blu-ray or DVD, export out interlaced to match the original.
In short, two exports.