Can someone please explain framerates?

mlewis wrote on 7/27/2003, 9:06 PM
I'm new to this, obviously, and am having a little trouble right from the "new file" pop-up window.

1st it lists a bunch of templates. Under that, it lists some other things, including a box for framerates. How does one go about choosing an appropriate frame rate, and why is it that each template can also have any of the frame rate options?
Thanks for any and all info.
matt

Comments

BillyBoy wrote on 7/27/2003, 9:28 PM
Short answer... leave it on the default which will change based on the template you select.

What is confusing at first is there are two main standards, the NTSC standard (North American and Japan and the PAL standard which is pretty much the rest of the world, but Russia has a slightly different one yet. <wink>

That odd value of 29.979 frames a second instead of a even 30 is actually a result of all things color television being introduced. Long boring story on how and why it came to be that odd value.

What template you pick depends on what kind of project you're going to make. If you're in the NTSC part of the world, stick with NTSC templates.
mlewis wrote on 7/27/2003, 9:55 PM
Thanks for the reply!
Why i'm even looking at it in the 1st place (i'm a default-till-i-know-otherwise kind of guy) is because i'm having trouble with the capture from my 8mm camcorder via Canopus ACDV-100 (converts analogue to a DV input that goes to my fireconnect IEEE card). I'm American, not European, so the PAL is out, and thus i use the default template. However, should i be slowing the framerate to 24fps (film), within the default template, on account of the 8mm/DV input? Should i switch to an entirely different template?

I ask because i am getting reproducable glitches in the video and audio tracks of my capture... maybe artifacts??? They look like quick flashes of color blocks partially obscuring the picture accompanied by a fizz in the audio, lasting under one second. It seems that if i decrease the framerate, this problem goes away (although i'll still have to do more "testing").
Guess i'm just wondering if it should be set to (film) 24 for any reason, given the analogue to DV conversion.
Thanks again for the reply and to anyone for any additional help.
matt
Chienworks wrote on 7/27/2003, 11:49 PM
Your 8mm camcorder isn't film, it's videotape, and it uses 29.97 for the frame rate just like all other NTSC devices do. So, you should be capturing at 29.97. If you're capturing through firewire then you really shouldn't have any choice in the matter anyway.

The glitches you refer to are probably dropouts and noise on the analog tape which become very funky when the ADVC-100 tries to digitize them. There may not be much you can do about them if your original tapes have infact degraded over time. If it's the result of dirty heads in your 8mm camcorder then you may want to consider a trip into the local service shop to get the heads cleaned.
jag5311 wrote on 7/28/2003, 1:21 AM
Hey Mlewis

I use the exact same setup as you. I don't have a digital camera, but my fathers HI 8 is what I have to work with. What is your computer speed, ram, etc.. I have a 3 ghz processor pentium 4 with 1 g of ram. I have yet to experience even 1 dropped frame, and I use advc-100 as well. Keep in mind, that sometimes I think when previewing them within a program such as vegas, you sometimes get those artifacts. Its kinda like seeing the thin squigly line at the bottom of your preview window. That is simply because you have analog footage. But on a tv, it doesn't show.
farss wrote on 7/28/2003, 7:01 AM
mlewis,
I think the last two posts are spot on. What may look like a minor imperfection on analogue tape can get turned into real nasties when its converted to digital.

The high end gear does a lot of preprocessing on analogue before it goes into the codecs. Without that a simple line dropout causes the codec to have a momentary seizure that you see as giant pixels. If its footage you really want to pull back from the brink you maybe better off getting a pro dub house to copy it through pro gear that will clean it up first.
RBartlett wrote on 7/28/2003, 8:54 AM
mlewis,

2 Q's:
Do you see the patchwork mess on the Vegas window - or on external preview (or both)?

Is the 8mm camera you are playing back on the same one that recorded it?

3 Comments:
Tolerances on analogue cameras are such that you sometimes need to enhance the sync signals and even the whole linearity of how time is represented. The chances are that the Canopus has time base correction and a field or frame store - but sometimes this is too little in the quest to import. Something extra between the camera and the Canopus can reduce the risks of errors at very little expense in signal quality.

If you lose your line timing on the digitisation process, the chase to find it again is likely to upset the sound sampling which on the Canopus converter is sprocketed with the video.

If it is only the DV-external preview mode that is upset - you might have a slow spot on the hard disc or too many other programs in your task bar (or a lower than ideal spec PC).