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Old August 8th, 2005, 01:15 AM   #1
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60i to 30p- dv natively 60i, need clarification

I've read that DV is NATIVELY 60i, and that 30p and 24p are merely just how the 60i footage is 'flagged' on the mini dv tape. I think I understand the basic premise of that, but here's my question:

I shot in 60i, but want it to be 30p for DVD- Do I capture it differently?
Can one capture 60i footage as 30p? Or do I have to take the 60i footage and process it AFTER capture. If so, why?

If its just a matter of 'flags' on the recording- is it possible to take that native 60i footage (that I also shot as 60i) and convert it to 30p or 24p with little or no quality degradation?

Whats the point of shooting 30p if DV is natively 60i? Whats the difference of 30p and 60i in this instance?

Am I making sense?

If specifics are needed to answer any of these questions:
I shot initial footage at 60i on my Canon XL2
My project is for output to DVD. I would ideally like to make it progressive 30p.
I use Final Cut Studio (lastest and greatest) on a Mac powermac G5

Should I shoot further footage at 30p if I've already started 60i?
Does it matter?

Any help is appreciated. I know this has been talked of often, apologies for redundancy- I just havent found specific answers addressing this issue...
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Last edited by Jeff Geissler; August 8th, 2005 at 01:18 AM. Reason: *clarification/mis-type*
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Old August 8th, 2005, 06:44 PM   #2
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If you wanted the footage in 30p, why did you shoot it in 60i? If the answer is "increased resolution," then you're right!

But seriously. I'll leave all the answers to other people, but generally, looking back at the questions, here are my takes....

While watching something you've recorded on the XL2 on a television, even when you recorded it in 24p, it is 60i, even though it has all the charm of 24p. It is flagged differently, so when you open it into the NLE, some settings are different. Like progressive, v. interlaced and things like widescreen will have different flags.

If you want it to be 30p, I guess (and correct me everyone if I'm wrong) the best thing to do would be to deinterlace the 60i by blending fields (maybe smoother than interpolation) and you will get deinterlaced video. But it won't look the same as having shot in 30p.

The difference between 60i and 30p (or 24p) even when it all shows up on a t.v. or monitor as 60i is the apparent cadence of frames. 30p footage shown as 60i will NOT look the same as footage shot at 60i. 60i looks like home video, or, in some cases, like a soap opera. 30p has its own asthetic which some find VERY appealing. 24p is more filmic in its cadence. The point is that they look different, even if you put them all on a VHS tape and play it in 60i.

As far as shooting further footage, my opinion would be to stick with what you started with. Consistancy in converted 60i will look better than a jarring switch in the middle of the piece, whatever it might be.

Others? Please?
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Old August 8th, 2005, 09:34 PM   #3
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The main issue isn't how the frames are flagged but rather how the frames are captured. The DVX for example can capture 24p or 30p. They only differ in the way which they are written to the tape. You still only have 24 or 30 samples per second vs 60.

If you have 60 frames per second interlaced and what to make that look like 30 frames per second you need to deinterlace, or blend the every two fields into one image and then write this new image back out to tape in 60i format.

Not sure if that made any sense or not.

But yes it's possible. You will loose some resolution - that's inevitable but it can be done quite well.

EDIT:

To clarify, what makes the footage have different looks is how many samples per second are taken. 60i takes 60 individual half frames per second. 24p takes 24 frames per second and 30p takes 30 frames per second. All these can be written to a normal interlaced video stream by various methods.
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Old August 9th, 2005, 11:55 AM   #4
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Thanks for the thoughts. I'm still not sure if I completely understand (specifically, in regards to how they are 'captured' in the camera) why 60i and 30p are different if its still 60i on the TV...at the same time you addressed it in the post- so perhaps I need to let it process mentally...

People have been telling me to stick with 60i if thats what I shot with, which makes sense, though I do like the 30p look better. I shot in 60i bc not all my cameras on the shoot could shoot in 30p - pretty much the main/only reason I didnt shoot in 30p or 24p, which I would have liked to...
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Old August 9th, 2005, 12:17 PM   #5
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Jeff,

NTSC video only captures at 60i and NTSC TV only plays back at 60i. However, just think of it as a 60i "wrapper." Inside the wrapper you can store 60i, 30p, or 24p.

In the case of 30p, even though you have 30 full frames, the TV shows you only half of the frame at a time. It will still have a different look than 60i material, because you're seeing two sequential pieces of the same moment in time, instead of two different moments in time. It takes the "reality" edge off of the motion.

You need to deinterlace after capture, and I would recommend DVFilm Maker or FieldsKit, since blending won't give you much of a different feel.

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Old August 9th, 2005, 12:39 PM   #6
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Quote:
Originally Posted by Joshua Provost
Jeff,

NTSC video only captures at 60i and NTSC TV only plays back at 60i. However, just think of it as a 60i "wrapper." Inside the wrapper you can store 60i, 30p, or 24p.

In the case of 30p, even though you have 30 full frames, the TV shows you only half of the frame at a time. It will still have a different look than 60i material, because you're seeing two sequential pieces of the same moment in time, instead of two different moments in time. It takes the "reality" edge off of the motion.

You need to deinterlace after capture, and I would recommend DVFilm Maker or FieldsKit, since blending won't give you much of a different feel.

Josh
YES!! Thank you! NOW it 'clicks'.

I dont know why this explanation worked while others didnt- as they all say the same thing ;)

Thanks man, that helped- in particular the wrapper analogy and the mention of the 30p being 2 of the SAME frame vs. two different/interlaced.

~jeff
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Old August 10th, 2005, 01:51 AM   #7
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Now, having discussed why I shot in 60i...
Should I shoot the interview sections of the DVD in 30p or stick with 60i?

The DVD has several different formats and levels of quality throughout (older archived vhs footage to newer digital material...) So, I think since the majority of the footage is in 60i, it should stay that way?

Can a timeline editor/dvd have both 30p and 60i footage in the same 'timeline'/project. (I'm in final cut studio)...

Any input is appreciated.

Cheers!
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Old August 10th, 2005, 11:38 AM   #8
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I should say again that it is better to process the 60i to 30p and keep it uniform than to do a switch-up midstream. Your NLE can have both forms of footage.
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Old August 10th, 2005, 12:16 PM   #9
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>Now, having discussed why I shot in 60i...
>Should I shoot the interview sections of the
>DVD in 30p or stick with 60i?

I'm curious to know the reason why you want to do this,
and what kind of pieces are you editing?

>The DVD has several different formats and
>levels of quality throughout (older archived
>vhs footage to newer digital material...)
>So, I think since the majority of the footage
>is in 60i, it should stay that way?

I'd say so, unless you have a very good reason.
Is the DVD to be viewed just on TV sets?

>Can a timeline editor/dvd have both 30p and
>60i footage in the same 'timeline'/project.
>(I'm in final cut studio)...

No, they can't not.
Although when viewed, it's going to look the same,
provided that the 30p footage is "packaged" in 60i.
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Old August 12th, 2005, 12:01 AM   #10
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O.K. That last answer does seem contradictory to my own. I should say that I use Vegas, and in Vegas (and perhaps Vegas alone?) the clips can exist simultaneously. Now, some confusion arises, because the clips (60i and 30p) can be side by side in a timeline that is 30p, or 60i, or 24p, or whatever, but the output will be uniform, that is, when you render it. So the straightforward answer is that you can have those three together in a timeline.

Let's say you have 60i, 30p, and 24p together in a 24p timeline and you were rendering out to NTSC DV. The 60i would look the same, as NTSC DV is 60i, the 30p would look the same, as it would have interlaced fields, but the fields would be identical, and the 24p would look the same, as the 2-3-3-2 pulldown would have already been inserted before (or during) printing to NTSC DV. So it would be 24p w/ pulldown.

In that way, you can have clips of different origins together, but in the end, they will all be spit out with a commonality. The timeline can contain different framerates, but the end result will have to be of a common framerate.
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Old August 12th, 2005, 01:06 PM   #11
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Yes, agree with what DJ said. Particularly 30p and 60i can co-exist just fine. Output interlaced and the footage won't be altered at all.
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Old August 12th, 2005, 02:12 PM   #12
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Quote:
Originally Posted by DJ Kinney
O.K. That last answer does seem contradictory to my own. I should say that I use Vegas, and in Vegas (and perhaps Vegas alone?) the clips can exist simultaneously. Now, some confusion arises, because the clips (60i and 30p) can be side by side in a timeline that is 30p, or 60i, or 24p, or whatever, but the output will be uniform, that is, when you render it. So the straightforward answer is that you can have those three together in a timeline.

Let's say you have 60i, 30p, and 24p together in a 24p timeline and you were rendering out to NTSC DV. The 60i would look the same, as NTSC DV is 60i, the 30p would look the same, as it would have interlaced fields, but the fields would be identical, and the 24p would look the same, as the 2-3-3-2 pulldown would have already been inserted before (or during) printing to NTSC DV. So it would be 24p w/ pulldown.

In that way, you can have clips of different origins together, but in the end, they will all be spit out with a commonality. The timeline can contain different framerates, but the end result will have to be of a common framerate.
Question:
I've heard that you can author 24p or 30p DVD's... Meaning, they are NOT 60i. They are authored progressive, which can be played on a progressive DVD player.

Thats the root of what I'm trying to get at. If you look at hollywood DVD's, they arent interlaced in many cases- correct me if I'm wrong. They have full frame progressive footage- and may be in its original frame rate (24/30)...etc.

Correct me if I've got that wrong. Just want to clarify what I think to be true is in fact... true.
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Old August 12th, 2005, 02:28 PM   #13
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Jeff,

True. I author almost exclusively 24p DVD's. 30p is also possible. However, this is really just shifting the burden to your DVD player to add the pulldown so the final output is the 60i your TV requires.

Not to say there isn't a good reason to author 24p DVDs. There are some great reasons. For one, you've only got so many bits in your bitstream. If you are using 24p instead of 30p or 60i, that's fewer frames... more bits per frame... higher quality. Also, full frames compress more efficiently than fields... higher quality.

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Old August 12th, 2005, 02:57 PM   #14
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Quote:
Originally Posted by DJ Kinney
Let's say you have 60i, 30p, and 24p together in a 24p timeline and you were rendering out to NTSC DV. The 60i would look the same, as NTSC DV is 60i, the 30p would look the same, as it would have interlaced fields, but the fields would be identical, and the 24p would look the same, as the 2-3-3-2 pulldown would have already been inserted before (or during) printing to NTSC DV. So it would be 24p w/ pulldown.

In that way, you can have clips of different origins together, but in the end, they will all be spit out with a commonality. The timeline can contain different framerates, but the end result will have to be of a common framerate.
They will look the same as what?

A) They will all look the same as they were shot? (24P, 30P, 60i)?

or

B) They will all look the same as one another (60i, or 24P, or 30P, depending on whatever timeline they're in?) ?
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Old August 12th, 2005, 03:01 PM   #15
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Quote:
Originally Posted by Jeff Geissler
If you look at hollywood DVD's, they arent interlaced in many cases- correct me if I'm wrong. They have full frame progressive footage- and may be in its original frame rate (24/30)...etc.

If you are watching them on a normal, non-progressive, NTSC TV then you ARE watching interlaced, but there are no jaggies because, again, the fields in this case are not two half-frames of two different moments in time like they'd be with 60i; the fields are two half-frames of one frame that is stored on the DVD as a single progressive frame.

At least dat is how I understand it!
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