I have spent the last couple of days trawling through the forums trying to find a solution to this problem, and although there seem to be many out there, a few that we have tried have not worked - so here's the deal.
We have shot a 30 minute infomercial on a Canon 5D Mark iii and a Canon 5D mark ii (25fps 1280 x 1080) - converting the original files into quicktime files through mpeg stream clip for editing. We then edited the entire sequence and have exported it, only for the broadcasters to come back and say it needs to be interlaced.
I have tried changing the settings of the sequence and re-exporting through premiere but it still came back as progressive from the broadcasters, even through our own file information programmes said it was interlaced.
I have tried upping the fps to 50 through this tutorial (https://library.creativecow.net/articles/solorio_marco/interlacing_progressive_footage.php)
And our information has come back as saying it is interlaced, upping it to 50fps and exporting from AE as a 1080 50i sequence with upper field first. This seems to have worked, but we forgot about the sound which is now in slow motion - so we are in the process of re-exorting with the original sound.
I have also interpreted the footage as upper field first on premiere and exported it with upper field first settings to see if that will work (which is currently rendering).
Do you have any more suggestions as to what we could do?
I understand that our next option would be to re-convert the original footage into apple pro res and then try and export an interlaced sequence from premiere pro, but even that I'm not sure how to do.
Any help would be great! Sorry if the post is a bit all over the place.