Disable Resample?

bakerbud9 wrote on 7/25/2006, 10:57 AM

What happens when Vegas renders a 23.976 fps project containing true 24 fps footage when the "Disable Resample" option is enabled?

The help file seems to indicate that "Disable Resample" is only applicable when the framerate of the event is slower than the framerate of the project. If this is true, then I guess true 24 fps footage in a 23.976 project will still need to be resampled, even if the option is selected, correct?

Comments

bakerbud9 wrote on 7/25/2006, 11:53 AM

Also, if a true 24 fps project comprised of audio and video is rendered to a 23.976 file, what is the effect, if any, that "Disable Resample" will have on both the audio and video?

Chienworks wrote on 7/25/2006, 6:19 PM

Faster or slower doesn't matter. With resample on, Vegas will combine all the source frames that occupy the same time slice as the output frame, in proportion to how much of each of those frames is inside the slide. If the source rate is faster than the project rate then more than one frame will be combined together for each output frame. If the source frame rate is slower then often only one source frame will be used, but if the source frame changes near the middle of the output frame then you will see two frames combined together.*

With resampling off, Vegas merely chooses the closest source frame to the output frame and copies it without combining with adjacent frames. Let's us a simple example of rendering 30p to 24p. The output file will contain source frames 1, 2, 3, 4, 6, 7, 8, 9, 11, 12, 13, 14 ... etc. with source frames 5, 10, 15, etc missing. If you render 24p to 30p then the output will be frames 1, 2, 3, 4, 4, 5, 6, 7, 8, 8, 9, 10, 11, 12,12 ... with every 4th frame doubled.

24 to 23.976 you'll get a similar result, but it will be every 1000th frame that is dropped.

*Actually it appears that recent Vegas versions are a lot more intelligent than simply blindly combining frames based on position. If this were true then most frames in resampled output would be combinations of adjancent frames and the result would be decidely fuzzy and doubled. I'm guessing Vegas only picks a few frames near the midway crossover point of each cycle to reample and fudges the rest into position without resampling. Certainly Vegas 6 creates a very smooth and clean output from resampled video than version 3 did. I'm just guessing though. I should perform some experiments to see sometime.

bakerbud9 wrote on 7/25/2006, 6:37 PM

"24 to 23.976 you'll get a similar result, but it will be every 1000th frame that is dropped."

Ah, dang... I was hoping it might be an easy way to slow down a true true 24 fps project by .1% for rendering to DVD. But what you say makes more sense. It seems my "wishful" thought of what "Disable Resample" might do that is the real bastardization.

Chienworks wrote on 7/25/2006, 6:42 PM

You could always set the playback rate to 0.999 and disable resample. That should match the frames up just about exactly. Chances are no one would ever notice the 0.1% speed difference.

bakerbud9 wrote on 7/25/2006, 6:47 PM

Problem is I don't think there's any way to set the playback rate to 0.999 when rendering to an MPEG-2 file. That's really the only time it would be needed.

TheHappyFriar wrote on 7/25/2006, 10:30 PM

you can render a file at a different framerate as the project no problem. just specify the rending framerate in the codec custom settings.

give it a shot & report back to us.

Chienworks wrote on 7/26/2006, 4:02 AM

Why would MPEG make any difference. Right mouse-buttton click on the clip, choose properties, set the playback rate to 0.999. That works whether you're rendering to MPEG, AVI, MOV, or even (*gasp*) RM. It is completely independent of any codec or project setting.

bakerbud9 wrote on 7/26/2006, 8:48 AM

Oh, I see whay you're saying. Yes, this works just fine if you've got a few clips in the vegas project (see my other recent posts about 24 fps vs. 23.796 fps). But its not the easiest thing to do for a large 24 fps project, especially where there's lots of audio that is synced to the original true 24 fps footage. In that case, the whole *project* truly needs to be slowed down by .1%, including all the audio.

bakerbud9 wrote on 7/26/2006, 9:00 AM

I've tried a few simple examples, but its hard to tell exactly what's happening... especially with the audio. I think I'll put together a long project with a click track and timecode so it will be easy to see what frames are dropped (if any) and if the audio looses sync or not.

bakerbud9 wrote on 7/26/2006, 9:07 AM

What would be nice: when Vegas detects that the render framerate does not match the project framerate it could ask the user if it should keep the project *framerate* constant or the project *duration* contstant. If the user selects "constant duration," then the project is resampled at the render framerate to fit the duration of the project. If the user selects "constant framerate," the the render framrate is matched 1:1 to the project framerate, and the duration of the project is modified, accordingly (and the audio is appropriately resampled).