23.976 DVD encode all wrong

johnmeyer wrote on 7/7/2006, 12:12 PM
I have, in the past, encoded 23.976 with the pulldown flag set and gotten beautiful DVDs. However, I've always used an external encoder. This time I am trying to encode using the MPEG encoder in Vegas. Something is terribly wrong.

My source material is video from a film transfer. The AVI header is set to show 24 fps (the original is silent film that was shot at 24, not 18, fps). The project properties in Vegas are set to 720x480 progressive, 24.000 (film). The media properties for the input media (which are DV files) show as Frame Rate: 24.000 (film), and I have changed the field order to None (progressive scan) because my film transfer process ensures that both fields of video are always from the same frame of film, and therefore there is no temporal difference between the upper and lower fields.

When I render, Vegas 6.0d offers the "DVD Architect 24p NTSC video stream" template. The template correctly shows the Frame Rate: 23.976 + 2-3 pulldown".

However, the result takes forever to encode and looks like it was actually encoded to 29.97, with additional crossfaded frames being added. When I bring the file into DVDA, it shows as being a 23.976 + 2-3 pulldown file, but the resulting DVD looks horrendous. Here is a link to one scene from the MPEG file that Vegas created. As you can see, there are all sorts of extra "ghosting" frames. Since this is a football game, there is lots of motion. The original shows each frame uniquely and crisply, and this is how it should be encoded (i.e., the MPEG file should show each frame individually, and then the DVD player should add the pulldown -- there should be no pulldown in the MPEG file itself).

Something is terribly wrong. Is this a known bug in Vegas?

Here is a link to a short (6 MB) sample of the bad encode:

Bad Encode

Here is a link to a slightly longer cut from the same portion of the exact same clip (it includes the entire play), encoded, via frameserver, using the external Mainconcept encoder:

Good Encode

It is perfect.

I should also note that the encode in Vegas took forever (almost twelve hours for a two-pass encode of 90 minutes of cuts-only project that had nothing more than B&W and levels adjustments). Normally, this would have taken just slightly over real-time (or 2x real-time for two-pass), plus another thirty minutes or so, per pass, for the levels adjust. I am now encoding via frameserver to the external encoder, and even though I am using some advanced parameters that considerably slow the encode, the estimated time is six hours, compared to the twelve hours it took, using faster parameters, in Vegas itself.

Either I'm screwing up somewhere, or something ain't right with Vegas. The external version of the MainConcept encoder (same one used in Vegas) works fine, on the same project.

[Edit]
Here's four frames from the original AVI:

Original AVI (four frames)

Comments

SonyDennis wrote on 7/7/2006, 1:22 PM
Vegas is doing framerate resampling from 24.000 fps to 23.976 fps, which will create blended frames. Go to the video event content menu, Switches, Disable Resample. This will also speed up the rendering.
Coursedesign wrote on 7/7/2006, 3:06 PM
...and the soundtrack would have been retimed automatically (if there had been one)?

Even many mid-level pros mix up 24.000 and 23.976 on camera settings.

So if the resampling is turned off and you render to 23.976 a clip imported as 24.000, the end result is just a slightly longer playback time for the same number of frames?


johnmeyer wrote on 7/7/2006, 5:52 PM
Fixed the problem using external encoder. I'll try changing AVI headers to 23.976 for next encode. No sound on this stuff, so no problem there. Wonder how people doing 24p video encode ...
Coursedesign wrote on 7/7/2006, 6:16 PM
They shoot 23.976.

High end HD cameras have settings for both 23.976 and 24.000, as do high end time code audio recorders.
johnmeyer wrote on 7/7/2006, 6:21 PM
They shoot 23.976.

Got it. So if I decide to experiment with "24p," I make sure I use 23.976 if I plan to encode to NTSC DVD with 3:2 pulldown.

Coursedesign wrote on 7/7/2006, 6:31 PM
...or slow down the audio in SoundForge, with maintained pitch.
johnmeyer wrote on 7/7/2006, 10:00 PM
To all:

I reset all the flags for my AVI files to 23.976 (actually 24/1001). I reset the Vegas project to 23.976 as well. I then had to slipstream 702 events to compensate for the slight change this introduced, which got progressively longer towards the end of each of the eight video files in the project. However, because of the nature of what I was doing (football films where the camera overexposed the beginning and ending of each sequence because of a sticky shutter), that took less than an hour (thought of writing a script, but it would take too long to debug). Also, I probably didn't need to do this, since all the events were now correctly labeled as 23.976, but I disabled resample on all events except those with slo-mo (I have a script to do this). Rendered a one minute test using the standard Vegas MPEG-2 template and all appears to be well.

I finally realized why I had never come across this problem before: All my previous film work has been at 18 fps, and that requires that I do my own pulldown in AVISynth and then encode as a standard 29.97 DVD (there are no standards for 18 fps). This is the first silent film I have come across that was shot at 24 fps (the footage included a shot of the scoreboard clock counting down, so I could measure the framerate exactly). All other 23.976 encodes were done from footage that I inverse telecined from over-the-air movies and also from various videotapes and laserdiscs. The flags on the IVTC material are always set as 23.976. Thus, I never have fed 24p into Vegas before.

I keep thinking I know this stuff, but in reality, I sure am one dumb SOB. Does ANYONE every figure out all this stuff?

Thanks to all for your patience.