Project Preferences vs Rendering

[grjohnson]

I viewed David's 24p Basics Tutorial and it clarified a few things for me, but left me unclear about something else.

In the Tutorial he said that it is best to do all editing, from all video sources, on a 24p timeline. This makes sense because the Vegas software knows what kind of video has been captured (24p, or 24pa or 30p) and sets it to the timeline automatically during editing, which I think is great. That way I can mix footage sources.

But when it comes to rendering, and assuming I want to render to an .avi video file, should I render in 24p DV or 30, after a mixed source project has been timelined in 24p?

Out of couriosity I took a project I had recorded and timelined at 30p video and then deliberately rendered it in 24p DV. The source was a JVC GR-DX77U consumer video unit. The rendered 24p product looked exactly like 16mm film footage, where in 30p .avi rendering it looked like normal video.

I repeated this experiment using 24p timeline editing with footage from my DVX100, shot in 24p, and rendered it in 30p DV .avi video. I then also I rendered the same material in 24p DV and, quite honestly, I could not see the difference between the two renderings. Why is that?

 

[David Jimerson]

Well, that's not what I said -- I said that if you have 24p footage, it makes no sense not to edit on a 24p timeline, and the reason I said that is because a lot of people 'round the net insist that either you should never edit standard 24p footage in 24p, or you should only edit in 24p if you're planning to go to film -- and both of those are nonsense, especially when using Vegas.

You should generally match your timeline to your footage. If you shot 24p, edit in 24p. If you shot 60i, edit in 60i. If you shot 30p, you can make a 30p timeline (just make a 60i timeline progressive).

That having been said, that's a guideline, and there are many various reasons to deviate from it. If you're mixing footage, pick a timeline for the framerate you want to be "dominant" -- for example, if you want a general 24p look, but have 24p and 60i footage, edit in 24p. Or, if you want to retain the look of the 60i footage and the 24p footage, edit in 60i.

And obviously, there many, many project-specific variations. The important thing to remember is that Vegas takes the worry away and will let you mix and match just about anything and render it any way you want.

24p footage will pretty much always look like 24p no matter how you render it, because you start with only 24 time samples per second, and no matter how you render it, that's all you end up with. Conversion to 30p will result in repeated frames so that (on average) the 24p frames are onscreen for the same amount of time they would have been if it were just 24p, so the motion ends up the same. Adding pulldown to go to 60i does the same kind of thing, only with conversion to fields instead of frames -- but again, the 24p frames are each onscreen for about the same amount of time they would have been in pure 24p, so it looks the same.

Interesting that you got a good conversion from 30p to 24p, because that's usually a miserable and loathesome result. You probably didn't have too much motion in that footage? If you did, you'd have seen horrible strobing and ghosting around moving objects.

 

[grjohnson]

Interesting that you got a good conversion from 30p to 24p, because that's usually a miserable and loathesome result. You probably didn't have too much motion in that footage? If you did, you'd have seen horrible strobing and ghosting around moving objects.

Ok, thanks for the quick response. That explains exactly what I observed. And I think I now have a better understanding of what you were saying.

And, in reference to the 30p - 24p conversion. Yes, it did look miserable except in steady shots, but I was really surprised at the 16mm 'look' I got from that experiment. At least I now know how to create an authentic looking old 16mm news film special effect if I need to do so in the future.

Gaines Johnson