How does playback on the 24fps DV cams work?

[Xesdeeni]

[Talking NTSC here] I understand that they record 24 progressive frames per second. But I'm curious how that comes out when I download it to the PC via firewire.

I have a DV cam that does 30 Fps (progressive). Of course this is completely compatible with 60 fps (interlaced), so the download software doesn't need to know anything about it.

But for these 24 Fps cameras, how do they interact with the software that captures to the PC? Do the telecine it in the camera so it's completely transparent to the software? Or do they record 24 Fps and rely on the software to recognize that it's 24 Fps rather than 30 Fps?

BTW, if they do the latter, can they get 25% more content on a tape, or dedicate 25% more data to each frame?

Just curious.

Xesdeeni

[theReal]

I think software playback on the pc is not a problem at all. The stream is just recognized and saved as 24fps DV-AVI. Software players can deal with all kinds of framerates, why should 24fps be a problem?

I'd find it more interesting to know how a normal ntsc tv-set deals with 24fps progressive video (if it can handle it at all).

I know from bb that 25fps progressive DV video plays nicely on normal PAL tv sets, but that's no wonder since it can easily be converted to 50fps interlaced. But what about 24fps to 60fps interlaced?

[sh0dan]

@thereal: One word: Telecine!

[theReal]

@thereal: One word: Telecine!So the camcorder does telecining on the fly?

[sh0dan]

Telecining is simply a matter of duplicating fields - not terribly complex, just store the frame, so it canbe sent out again.

[Xesdeeni]

So the stream transferred (via 1394) to a PC would still be 29.97 fps, as with the interlaced or progressive modes....

Is the video then converted to actual 23.976 fps before editing? Because if it's not, wouldn't you introduce non-film edits by breaking up the telecine? Wouldn't that cut down on the "film look?"

Xesdeeni

[Crucio]

i assume youre talking about a camera such as the panasonic agdvx100? If so, this camera has 3 settings, 30fps progressive, 60fps interlaced, 24fps adv, and 24fps normal, the advanced mode is 24p in 30fps that just makes frames easier for programs like final cutpro to inverse telecine, while the normal is 30fps video with fake frames in it to make it look ok on a non progressive tv. hope that helps!

[mikecito]

I own the ag-dvx100 - it does telecine on the fly so that it comes into your software as 29.97 fps video. You can easily pull out the 24fps video by inverse telecine, and you end up with the original frame captures, as if it were film, because it's not mixing fields to make the new frames - it's using entire frames and adding them as if you were using actual film.

It's by far the best camera I've ever held in my hands, and has some incredible options. If you have the $3000-$3500 to spend on a camera, this would be the one. The only other choices in this price range don't have true progressive video at 24fps - although I believe the canon has some type of "frame" mode that mimics it. I've read the results are poor, however.

Definitely worth the $$$ for the Panasonic - I just wish there was an autofocus in progressive mode, and possibly an adjustable gain. I'm not pro enough yet to handle lighting, focus, and zoom all at once! :)

[Crucio]

the focus was taken out by panasonic because they were afraid people would ruin their videos with it. Maybe autofocus and progressive just doesnt mix ?

[mikecito]

Well - it's probably a good thing they did. This way, I have to learn to focus instead of just pointing at my actor. I do like having the control with the few times I've used it for cool focus changes, but it would be a nice option to have when I'm shooting in 30p at a family activity or sporting event. It's hard to catch candid action when you're bumbling with the focus on a tight shot.

So - progressive + autofocus = problems? I wonder if anyone out there knows if there is truth to this. I mean, the camera already has all the parts built in for 60i, so why would they make the functionality not available under progressive? Interesting - you might have something. Even my 35mm autofocuses, so it can't be a full frame issue - maybe the processor is to busy cranking out those progressive frames and doesn't have time to think about focusing too. :)