How to convert DV to 320x240x60p?

[stonerunner]

Hi all

Thank you for reading this. I am doing a video shoot with two cameras: one is a DV camcorder, the other is a digital camera shooting 320x240 at 60fps. I am editing and doing effects at 60fps, with plans to later output to DVD and VCD (and YouTube). For the sake of consistency, is there a way I can convert the DV down to 320x240, and make the odd fields into one frame, and the even fields another?

Thank you.

[guns1inger]

Yes. However having done this, I wouldn't bother trying to go back to DVD as the results will be rather unsatisfactory.

You can do this conversion very simply in virtualdub using the Bob Doubler and Resize filters.

[jagabo]

Yes, there are many deinterlacing filters that can change each field into a frame -- this operation is usually called a "bob".

VirtualDub has one built it but it's not especially good. AviSynth has many which are better: TDeint(mode=1), LeakKernelBob(), Yadif(mode=1), and the best, but horrendously slow, TempGaussMC_beta1(). All of these retain full resolution in areas that aren't moving, and try to be at least a little smart about areas that are.

After bob'ing you reduce the frame to 320x240. A typical AviSynth script might look like:

AviFile("filename.avi")
Yadif(mode=1, order=0)
LanczosResize(320, 240)

The order=0 argument is to specify bottom-field-first rather than top-field-first (order=1). If you use the wrong field order the result will be very fast-jerky.

You open the script with your editor as if was an AVI file. If your editor doesn't support AviSynth scripting you can use VirtualDub or some other program that does, then save to an intermediate file that your editor will accept.

[stonerunner]

Thanks jagabo and guns1inger

guns1inger, I'm not too worried about quality (It's more for learning anyway). Working in 320x240 lets me render stuff quicker, and not get caught up in the high-def (heh, or even standard def..) craze. I am messing with editing and basic CGI integration.

[stonerunner]

Whoa thanks jagabo! I didn't see the second half of the post before replying.

[jagabo]

Oh, and if you literally need 60 fps (not 59.94) you'll need to add the frame rate conversion too. In AviSynth you can specify

AssumeFPS(60)

after bob'ing to simply display each frame a tiny bit faster (doesn't maintain running time, will cause A/V sync problems, but will play very smoothly), or

ChangeFPS(60)

which will duplicate one frame out of every 1000 causing a small jerk every 30 seconds or so (but running time will remain unchanged and you won't have A/V sync errors).

AviFile("filename.avi")
Yadif(mode=1, order=0)
LanczosResize(320, 240)
ChangeFPS(60)

In VirtualDub's Frame Rate dialog, the equivalent of the former is to use the top portion of the dialog and change the source rate to 60. The equivalent of the latter is use the middle portion of the dialog and Convert FPS to 60.

[stonerunner]

Ah, crap. I hadn't thought of that. Actually, I'm recording all of the sound separately anyway. What do I do, then, since one of my cameras is 60fps and the other is 29.97/59.94? Or is that covered somewhere.

[jagabo]

Use the second of the two options for frame rate conversion, ChangeFPS(). There will be no A/V sync problems and you may not even notice the tiny jerk every 30 seconds (as one frame is displayed twice). Many of them may fall in areas where there is no (or little) motion -- you won't notice those.

[stonerunner]

Sweet. Thank you