Mastering 24p DVDs from HD using Premiere Pro.

24p DVD mastering.

First some basics, there is no true 24p mode on standard DVD, there are is only 60i encoding (and 50i for PAL.)  So all those film source are encode to DVD by adding 3:2 pulldown (or 2:2 for PAL with a 4% speed up for 24p sources.)  How this pulldown is added impacts how well your DVD presents on today's common progressive displays. 

Adding 3:2 pulldown for NTSC DVD creation has been has been tricky, seemingly there are lots of dead ends (like using Encore to encode directly to 24p -- this should work, I have made several blurry DVDs trying to use it.)  This is one of the most common support questions.  McCarthyTech has a good blog post on using AE to manually insert pulldown before encoding as 60i, and this will work everytime.  It was his post that has prompted this one, as there is an even simpler way using Premiere CS3+ directly, and if you are careful it can be even better for final presentation.  McCarthyTech's technique can be improved if we trust the MPEG2 encoder can to add the pulldown using repeat flags.  Fortunately this works correctly using the 23.976p encode mode within Premiere's Adobe Media Encoder (MPEG2-DVD preset), now we just have to watch out for other Premiere limitations.  

The advantage of pulldown that uses the MPEG2's repeat flags, this can help with quality as only fields used to construct the 24p signal are compressed, the repeat flag pad the data out to 60i. This flags also help progressive scan DVD players reconstruct the correct 24p signal more reliably. The manually created pulldown in AE works for most situations as many DVD players can use the data-rate pattern to guess the pulldown, but it is not always extracted correctly (seen as a weave pattern during motion.)  Of course there is no issue for non-progressive outputs where the display is reasonable for pulldown detection (if needed.)

The way I produced several 24p DVDs in the last weeks is to export out of Premiere as a 1920×1080 24p (23.976) master CineForm AVI, then I used VirtualDub and scale using Lanzcos 3 filter to 720×480 and export out to CineForm 444 SD.  Load the SD clip back into Premiere SD 24p preset, interpret footage back to 16×9, and export with Adobe Media Encoder to MPEG2-DVD 24p. Encore will take this file without further transcoding.  Now that seems to be an odd path and it is, plus using VirtualDub is unnecessary, but the export to 1920x1080 master first is a very important step. 

I first made the mistake of exporting my 1080p timeline directly to MPEG2-DVD, and it looks horrible.  I've made this mistake before, as you simply expect it to work (never has in Premiere up to the tested PPro v3.2), but here why it doesn't always do what you want.  When you add any spatial distorting filter (motion, blurs and sharpens, etc), you see the results previewed at 1080p, any scaling for your preview display is applied after the filter operations -- so you adjust you filter so they look correct on a 1080p source.   We you use the Adobe Media Encoder, the scaling is applied first, before any of your filters -- as a result your output doesn't look like you previewed -- spatial filter are around 2.5 times stronger than you intended.   In one of my recent projects, I was using the additional resolution of the 1080p source to reframe for a nicer DVD output, see below how much it matters in what order of operations that scale occurs (see below.)

The image on the left is soft and badly aliased, and it looks far worse in motion.  Simply exporting the timeline to 1080p first, then using that new file to export to DVD solves the problem, without ever leaving Premiere.  The VirtualDub step in my above technique can be as simply skipped, as loading the exported 1080p AVI into Premiere will use the CineForm importer's own Lanzcos 3 scaler for exactly the same results, much faster and more convient.