Converting 60 fps to 30 fps

kelcey · Member Joined: 05 Jul 2008 Location: United States

Hello everyone,

So I capture video at 60 fps (can't capture at 30 fps). I'd like to scale the video down to 30 fps (skip every other frame... do whatever). I'm able to do so in virtualdub, but the audio gets all messed up. I would be more specific... but there really aren't words to describe it

.

Anyways, I was wondering how I can say maybe convert to 30 fps by processing every other frame and keep the audio in sync.

Thanks everyone.

zoobie · Posted: Jul 23, 2008 04:35

best to find out why you can't cap at 30
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darkknight145 · Member Joined: 19 Feb 2007 Location: Australia

are you sure it's 60 frames per second and not 60 fields per second, if it's fields per second this is correct for NTSC, no conversion needed

SatStorm · Posted: Jul 23, 2008 07:13

AIPTEK cameras capture at 60fps, I have the same problem myself. So do some mobile phones.

I do a fast frame convertion with virtualdub when that is needed. I also keep the original as raw data, until a good solution appears. There are some solutions already out there, but they are far from perfect in my opinion (always).

jagabo · Member Joined: 09 Dec 2005 Location: none

Make sure you change the frame rate in the correct section of VirtualDub's frame rate dialog:

This will simply throw away every other frame and create a 30 fps video.

You can do the same with AviSynth's ChangeFPS(30) or SelectEvery(2, 0).

kelcey · Member Joined: 05 Jul 2008 Location: United States

jagabo · Member Joined: 09 Dec 2005 Location: none

edDV · Posted: Jul 23, 2008 12:16

Any live 480p or 720p broadcast will be 59.94 frames per second. 480i and 1080i will be 59.94 fields per second (29.97 frames per second). All update motion at the 59.94 rate.

If you drop the 480p or 720p frame rate to 29.97, the video will appear just as choppy as if you viewed just one field of 480i or 1080i.
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kelcey · Member Joined: 05 Jul 2008 Location: United States

Let me see if I can create some very short clips. I'll overly compress the video so it'll be a tiny download.

edDV · Posted: Jul 23, 2008 15:28

kelcey · Member Joined: 05 Jul 2008 Location: United States

I meant I'm going to create 2 clips. One will be the original 60 fps. One will be converted 30 fps. I'm going to compress them a lot so they're easy to download.

kelcey · Member Joined: 05 Jul 2008 Location: United States

Okay. So I've gotten it to work using SelectEvery(2,0) in avisynth. Thanks jagabo.

I actually tried changeFPS late last night... but maybe I mistyped it because some error popped up and I was tired. But selectevery works beautifully. Anyways, to let you know what happens when I use virtualdub convert to fps... the audio either just gets mangled (sounds like it slows down... maybe a mix of audio from various places?) or it just drops audio completely. I also didn't get the VBR warning. But anyways, I'm using MeGUI with avisynth now and it's working very well.

Thanks for the suggestions everyone!