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Old March 9th, 2010, 05:51 PM   #1
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24p into 25p......

hey guys, answer me this....
Thinking about getting another cam and the Canon XL2's are really good value on the US. Ebay..... but, they are NTSC, and im in Pal land with lots of already owned Pal cams.
What are the drawbacks of converting 24p to 25p (besides time spent doing it) in Vegas?
I do a lot of multi cam shoots, so syncing is important.

I did a quick test with my GY HM100 in 24p mode and converted it in Vegas with no obvious change in quality, but im wondering if im missing something.

Any input would be greatly appreciated, even if its only theoretical, still please put in your 2 cents worth.
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Old March 12th, 2010, 01:59 PM   #2
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Usually they play 24 fps material at 25 fps on PAL. They may or may not do a pitch shift to correct for the 4% speed difference, however, this process doesn't always work with some music. You'll also find time code difference between PAL cameras and what are NTSC cameras because the latter uses 29.97 fps.
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Old March 12th, 2010, 03:57 PM   #3
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Hi Gerald,

I've never converted 24p to 25p, but have downconverted HDV (shot with a Canon HV30) to SD (1440x1080 HDV to 720x480 SD) using Cineform's Prospect/HD Link.

So, if you've already tried converting it on Vegas with the JVC footage, I'd think it'd be the same process as using Canon's XL2 24p footage? And if you think that there's no change in quality, then you should be good to go.

Apologize if that doesn't help you out.

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Old March 12th, 2010, 05:27 PM   #4
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Gerald, its not just the frame rate, PAL has a much higher SD resolution than NTSC (576X720 vs 480X720). At 24/25 fps you can see the difference. You really need to work out what you are going to use the camera for. XLs are great cameras, but you might still be better off with something HD.
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Old March 12th, 2010, 07:51 PM   #5
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thanx for your replies,
all my cams are HD except one, and that is an old sony sd handycam with virtually no usable manual controls. I mainly film bands with about 4 to 6 cams in the room.
I may be wrong but the frame size IMO shouldnt be and issue, The sd sony captures really well as an upscaled 1080i MXF file in Vegas, and looks way better than it should considering it came from a dodgy little sd cam.
My thoughts on the XL2 are that for the price, the manual controls and picture quality are exceptional, even if only SD, would love to hear from anyone who consistently upscales their XL2 footage.
Its the 24 to 25 that is burning my brain, do you just play 24 frames per second in a 25 p project, then render to a new track? Where does Vegas get the extra frame from in the new track? If you disabled resample b4 render, as you would have to to keep your quality, where does the extra frame come from?
The more I think about this, the worse it gets, lol, they are going very cheap though.
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Old March 13th, 2010, 05:39 PM   #6
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Quote:
Originally Posted by Gerald Webb View Post
Its the 24 to 25 that is burning my brain, do you just play 24 frames per second in a 25 p project, then render to a new track? Where does Vegas get the extra frame from in the new track? If you disabled resample b4 render, as you would have to to keep your quality, where does the extra frame come from?
The more I think about this, the worse it gets, lol, they are going very cheap though.
AFAIK (I haven't tried it) you don't actually get an EXTRA frame, you just get 25 of your existing frames in 1 second instead of 24 of your existing frames - so everything is essentially "speeded-up" (hence the comments about pitch-shift).
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Old March 13th, 2010, 06:06 PM   #7
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In the digital world, render is done at the bit level, not by frames. Render 24 to 25 fps (or anything else) unless there's something wrong there is no pitch shift. The only problem with the XL2 is that it is not HD. It will never be surpassed as the best miniDV camera ever. If you are distributing on DVD, you get as good a result with an XL2 as with anything else. BRD is another story. PAL XL2 footage upresd to 720 p looks fine. Depending on the room size, you will also need the wide lens. Please don't disagree now, its a prediction, but if you buy an NTSC camera in PAL land you will regret it. There's and XL2 forum on this site that should answer any other questions you have (sorry, just noticed you already posted there).
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Old March 13th, 2010, 07:34 PM   #8
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In the digital world, render is done at the bit level, not by frames. Render 24 to 25 fps (or anything else) unless there's something wrong there is no pitch shift.
Hmm.. and the bits make up the discrete frames (which is why/how come there are different frame-rates!?!) which can be progressive or interlaced and may or may not be long gop.

If you have a project that has (say) 10,000 frames (your NLE timeline will tell you how many frames you have) which was shot at 24fps your 10,000 frames will last for 10,000/24 secs = 416.6 secs if you then change the frame rate to 25fps, your project will then only last for 10,000/25 secs = 400 secs - a difference of 16 secs. This means that your audio will be played back faster - creating a pitch-shift (unless it is corrected by the use of relevant software which is readily available for that purpose).
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Old March 14th, 2010, 01:31 AM   #9
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Hi Steve, true, and that's probably the best way and a common way of doing it. But just as there's more than one way to skin a wombat, there's more than one way to convert 24fps to 25 fps PAL, also AFAIK none of them perfect. Different render engines will do it differently. For example, they can split the footage (if its not interlaced) and apply 2:2:2:2:2:2:2:2:2:2:2:3 pulldown, which causes some judder. Vegas left to its own devices seems to blend fields, which can make the action look strange. In both these latter cases you end up with 25 frames where initially there were 24 and your audio stays synced without touching it.
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Old March 14th, 2010, 04:39 AM   #10
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Since you seem to be doing multi camera shoots, apart from the frame rate, I'd also be concerned about colour matching a NTSC camera that's meant to seamlessly inter cut with PAL cameras on a regular basis.
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Old March 14th, 2010, 06:48 AM   #11
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Originally Posted by Steve Renouf View Post
AFAIK (I haven't tried it) you don't actually get an EXTRA frame, you just get 25 of your existing frames in 1 second instead of 24 of your existing frames - so everything is essentially "speeded-up" (hence the comments about pitch-shift).
I have tried this a few times. If you want the 24p footage to play back speeded up to 25fps, you have to adjust the clip playback rate in Vegas. If you do this with resample disabled, there will be no artifacts introduced, however you do need to be careful with the audio.

If you just try to render a 24p clip from a 25p timeline, to a 25p output format, Vegas has to create new frames, and there will be artifacts in areas where there is a lot of motion.

Richard
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Old March 14th, 2010, 04:56 PM   #12
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Hi Gerald,

I own a PAL version of XL2 and did some converting of 25p material into 24p with no quality loss. AFIK 25p->24p conversion is a simple process that doesn't degrade picture quality at all, unlike 30p->24p because 25p footage is just 4% faster than 24p meaning that 24p is just slower so you shouldn't worry. I even converted 50i footage from a crapy Sony cam and it came out nicely, only deinterlacing artifacts.

Hope it helps
Piotr
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Old March 14th, 2010, 05:03 PM   #13
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I just noticed you want to add NTSC cam to your PAL. In this case, my post doesn't help you at all. I read somewhere that NTSC conversion into PAL or vice versa isn't very smooth... BTW, I think I would prefer getting a PAL cam to NTSC cam since you get about 20% of resolution gain and better colors.

Piotr
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Old March 14th, 2010, 08:45 PM   #14
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thanx for the replies,
I would love to get a PAL version of the XL2, but they are just not around unless you want a brand new one for about $5k, which if I wanted to pay that much Id prob get an XHA1s instead.
There is a ton of NTSC ones on US ebay for about 2k with a heap of extras as well.
Can you get a firmware conversion for XL2??
I know they do it for XHA1s, but Canon charges about $600,00 to do it.
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Old March 15th, 2010, 04:20 AM   #15
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thanks heaps for the input fellas,
did some more research on this today with Canon Australia, I asked them about updating the firmware on an NTSC cam over to PAL. Cant be done, :((( needs a whole new mainboard to make it happen, which they will gladly do for $1200.00. :(
Kinda takes the fun out of getting one cheap from the US of A.

I still may have a crack with the NTSC version though, the audio from this cam is never used anyway apart from syncing it on the timeline, in my live performance multi shoots, I want this cam for me at the front of stage, sound is a mess there anyway.

I may be a bit slow on this, but if I drop the clip in a 25p timeline and do absolute frames and disable resample, the clip will appear to play faster ( as Steve pointed out )
but then I need to stretch it back out to sync with the other cams........ then what?

Im going to do a multicam shoot of a clock,
one 1080p 25p,
and one 24p,
then render it out split screen and see what happens.....
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