3:2 pulldown vs. non-interlace

[headless chicken]

Up until recently, I've always used TMPGEnc's wizard and CBR to encode SVCDs. The default for 23.976 fps is usually 3:2 pulldown encode paired with non-interlace (progressive) source. It's come to my attention that if I just load the avi the settings prefer non-interlace for the encode option. Is one neccessarily better than the other? Does 3:2 give you a jerkier playback than non-interlace?

[johns0]

Files that are 23.976 are most of the time progressive so you have to use 2:3 pulldown with source progressive so that dvd players will play them at the proper framerate of 29.97.

[junkmalle]

I think the only difference is whether or not the 3:2 pulldown flag is included in the MPEG file. Since NTSC TV can only display 60 field per second video both files will be pulled down on playback.

[johns0]

Huh?Both files?You still need pulldown flags on 23.976 files for the dvd player to play 29.97.

[adam]

If you are encoding mpeg2 at 23.976fps then you have to use the 3:2 pulldown option. Its required for both the SVCD and DVD standards. You could use the non-interlaced option and then add pulldown flags to the stream afterwards using pulldown.exe, but the quality would be identical.

[junkmalle]

Just as a test, I made a 23.976 fps, 480x480, 2000 kbps CBR, MPEG 2 file without the 3:2 pulldown option. I then burned the file to an SVCD with Nero Burning. Nero complained about the file but I let it continue making a non-compliant SVCD. I verified that the MPEG file on the SVCD was still 24 fps progressive using VirtualDub. I put the SVCD in my DVD player and it played the disk without any problems on my NTSC-only TV. So even without the explicit 3:2 pulldown flag, the DVD player performed the 3:2 pulldown -- it had to to play on an NTSC TV.

Of course this may vary with different brand and different model DVD players. Some may refuse to play such disks.

[adam]

Yes some DVD players will autotelecine any NTSCfilm footage and do it well. Many will not recognize the disk, or will simply output it at 29.97fps without doing a telecine, which results in a long pause or garbled frames every second. Also, even if your player does do an autotelecine, there is no guarantee that it will follow any set pattern since there are no pulldown flags specifying the specific RFF/TFF pattern. This is what happens with VCDs and the smoothness of the playback will vary from player to player, unlike with properly encoded mpeg2 material which will be played back on all machines about as smoothly as is possible for NTSC.

[junkmalle]

Yes some DVD players will autotelecine any NTSCfilm footage and do it well. Many will not recognize the disk, or will simply output it at 29.97fps without doing a telecine, which results in a long pause or garbled frames every second. Also, even if your player does do an autotelecine, there is no guarantee that it will follow any set pattern since there are no pulldown flags specifying the specific RFF/TFF pattern. This is what happens with VCDs and the smoothness of the playback will vary from player to player, unlike with properly encoded mpeg2 material which will be played back on all machines about as smoothly as is possible for NTSC.

I suspect a lot of players will telecine at the frame level rather than the field level. That is, they would display the 24 fps MPEG frames for 1/30 second and display every 4'th frame twice, resulting in jerky playback.