Animation: Explaining 24p Advanced
An animation showing how 24p Advanced mode works.
Note: If you cannot see the video, install Macromedia Flash Player 8 and return to this page.
OK, so I had to do the 24p advanced mode since I went ahead and did standard. I duped the standard comp and swapped a few things out and used Pedr Norby's most excellent plug-in, Shine along with After Effects.
Here's my brief textual explanation to go along with the diagram:
- The recorded material originates as 24 progressive frames a second. In this example there are four frames, A, B, C, and D.
- The 24p advanced mode applies a unique 2:3:3:2 pulldown cadence to preserve the original 24p frames inside the 29.97 interlaced DV stream.
- The cadence begins by recording one frame onto two fields and the second frame onto three. Instead of recording the third frame onto two fields, it is recorded onto three, and the fourth frame is recorded onto two. When the original frames are mapped to fields, the pattern is AA BB BC CC DD.
- An NLE that understands the mode’s pulldown pattern throws away the “BC” frame (the BC frame) and uses the remaining frames to restore the original progressive footage.
Bottom Line
The 24p advanced mode sacrifices compatibility with NTSC video for frame integrity and is best suited for doing film-out, creating a 24p DVD, or creating video for Internet or CD-ROM/DVD-ROM distribution.