8mm Forum: Re-recording Troubles.....

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Topic: Re-recording Troubles.....

Alan Rik
Film God

Posts: 2211
From: New York City, NY, USA
Registered: Jun 2003

posted May 21, 2004 09:57 PM

So in the name of nothing good on television and having seen all the new DVD releases I decided to have a hand at syncing up a DVD with a Super 8 film to see if they would stay in sync. NO!! Not even close!
My first try was the Pod Scene from Phantom Menace. It was way off. Then I realized the DVD is the extended scene. Oops!
Then I tried Rocky. At the beginning it was in sync. Then it literally took only less than 30 seconds and i noticed the drift. So I went and used the speed adjustment and then it was on, then ahead, then behind!
In the end for me...wild synch was a dismal failure. Using a GS1200 too. On the crummy NTSC system with its strange 29.97 fps rate!

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Brad Miller
Administrator

Posts: 525
From: Dallas, TX, USA
Registered: Jun 2003

posted May 22, 2004 08:40 PM

You are overcompensating. When you see the DVD is lagging behind, you have to STOP the film and let the DVD catch up, then make a tiny, tiny speed decrease of the projector.

When you see the film is lagging behind, you have to STOP the DVD and let the film catch up, then make a tiny, tiny speed increase of the projector.

If you are using the speed as an exclusive means to "resync" during the reel, you will fail. You have to run each reel until you get to the point where you can maintain sync for a solid 5 minutes minimum. Then you can rewind the reel, back up the DVD and go to town...without touching that speed control. (Many people turn the speed control up for rewinding.)

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Alan Rik
Film God

Posts: 2211
From: New York City, NY, USA
Registered: Jun 2003

posted May 23, 2004 01:04 AM

I am a little confused. Does this mean that the end product will be a combination of 5 minutes of uninterrupted audio then a punch in for another 5 minutes, and so on. How does that affect the continuity of sound?
That sounds like a terrible way to re-record your features. And a nice way to burn out the motor and bulb on your projector. Does anyone else out there do it this way?

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Kevin Faulkner
Film God

Posts: 4071
From: Essex UK
Registered: Jun 2003

posted May 23, 2004 07:53 AM

Hi Alan,
It will be a nightmare trying to do this "wild" with all this starting and stopping etc. You really need to get your hands on one of these units which Pedro sells. This will allow you to crystal lock your GS at 30FPS (29.97). At least having the machine locked at the correct frame rate is a start. The only problem you then have to deal with is the change in cut between the DVD and the film.
I have recorded complete features in this way using the Pedro Crystal Sync unit running at the UK's 25 FPS.

Kevin.

--------------------
GS1200 Xenon with Elmo 1.0...great combo along with a 16-CL Xenon for that super bright white light.

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Alan Rik
Film God

Posts: 2211
From: New York City, NY, USA
Registered: Jun 2003

posted May 23, 2004 08:00 AM

Hi Kev-
I remember Pedro saying that he didn't make the unit to sync to 30fps yet. Do you think it would be possible to get a PAL DVD player, PAL DVD, and sync it up that way? I could use a Portable Code Free player with its own screen, thus eliminating the need to get a new tv and then voila...the DVD should be playing back at 25fps.
Do you think that would work?

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Kevin Faulkner
Film God

Posts: 4071
From: Essex UK
Registered: Jun 2003

posted May 23, 2004 04:11 PM

Yes you are right. I was talking to Doug Meltzer this afternoon who is in the UK at the moment and then I realised my blunder.
I would think that Pedro could make a 30FPS unit if he had enough people interested and yes if we can play NTSC on our DVD players here in the UK then why cant you use a PAL/NTSC version in the US. I think it should be possible if you have multi system PAL/NTSC TV's in the US like we have over here in the UK.

Kev.

--------------------
GS1200 Xenon with Elmo 1.0...great combo along with a 16-CL Xenon for that super bright white light.

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Ugo Grassi
Jedi Master Film Handler

Posts: 506
From: Avellino (Italy)
Registered: Dec 2003

posted May 23, 2004 05:18 PM

30 ft/s? Why?
NTSC goes at 60 Hz for 60 half frames for second=30 frames, but this is the television frame rate.
I know when a 35mm film is projected for a NTSC television, every 4 frame is made an artificial frame using the last half frame of that 4, and the first half frame of the next 4. After 24 frames you obtain 6 new artificial frames.
Result: you have 30 frames for a scene which on the 35mm film is over 24 frames.
I think to drive the GS1200 at 30 ft/s isn't the solution.

--------------------
Bye
Ugo

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Kevin Faulkner
Film God

Posts: 4071
From: Essex UK
Registered: Jun 2003

posted May 24, 2004 03:19 PM

Funny you should say that but originally I thought it would be 24 FPS then thought maybe not. Now I'm not sure because I agree with your theory Ugo.
Ugo I have had another 3 GS with that capacitor problem and am dealing with a guy in Germany who I think has the same problem. If it looks like it is the case then I will post the problem on the forum here.

Kev.

--------------------
GS1200 Xenon with Elmo 1.0...great combo along with a 16-CL Xenon for that super bright white light.

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John Whittle
Jedi Master Film Handler

Posts: 791
From: Northridge, CA USA
Registered: Jun 2003

posted May 24, 2004 05:24 PM

When we transfer film to video, the film rate is 23.97 fps and the video rate is 29.97 fps (due to the color burst subcarrier at 3.58 mhz--that number is rounded as are the others).

This is accomplished by a 3-2 repeat film frame one goes to video fields 1, 2, 3, then film frame two goes to video fields 4, 5 and it repeats.

There are now DVD players which can do reverse telecine taking the film back to 24 fps and doing progressive (all 480 lines in a single picture) and it's displayed at 72 pictures per second to remove flicker (that you'd see at 48 pictures per second).

To sync a DVD back to film, what you need to do is phase lock the video ouput at 29.97 with a converter that locks the projector to 23.97 and then it will stay in sync. It works, we dubb full feature pictures that way.

This is basically a 5-4 lock up and what the converter does is run the signal up to a number that is common to both frame rates and then locks them and outputs a control to the projector motor to lock it up.

That's the way we do it in commercial post production houses and if you can come up with that little sync box there is no reason why it won't work. As an added benefit we don't pitch correct the sound (23.97 vs 24) so there won't be a sound pitch change when you re-record.

John

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Alan Rik
Film God

Posts: 2211
From: New York City, NY, USA
Registered: Jun 2003

posted May 24, 2004 10:55 PM

Aha! Now we are getting somewhere! Can anyone who is familiar with Pedro ask him if he can use his genius to construct such a box? And how about the name of a DVD player that does this?
this is great news!

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Brad Miller
Administrator

Posts: 525
From: Dallas, TX, USA
Registered: Jun 2003

posted May 25, 2004 12:08 AM

quote:
Does this mean that the end product will be a combination of 5 minutes of uninterrupted audio then a punch in for another 5 minutes, and so on.

No, once you have been able to maintain sync for a solid 5 minutes, it means you have found that magic spot on your speed control where you can maintain speed for extended lengths of time and in most circumstances you can then maintain speed for the length of the reel. Once you find that speed, do not touch that knob again. If you start things up and see one is a couple of frames ahead of the other STOP and back up! Never try to compensate on the speed control when you are first starting a reel or you will be fiddling with it the entire movie.

You should also project the 8mm image on a small screen the same size and right beside your tv monitor. Then don't pay attention to lip sync...just watch in between the two images to ensure that both the video and film are flashing their camera cuts at the same instant. If you see one is starting to flash just a hair before the other, it's easy to tap that speed control enough to compensate. As such, using this technique you should never get more than 1/2 frame off throughout a reel.

Also, you really should clean your prints before re-recording. FilmGuard will do the best job, but use whatever you can get your hands on. If there is any dirt on the mag tracks, you will be recording dropouts and your high frequencies will suffer.

If you really want to get picky about things, use the leader to record a loop of pink noise onto it. Then using an RTA you can check the playback (on the same projector's head) to see where the deficiencies are and make corrections via an inline EQ. Once the EQ is set, you simply put it in between your DVD and projector so it applies the boost/cut pre-recording. Then verify with another strip of pink noise recording that upon playback you do truly have a flat frequency response being outputted. This is how I do all of my re-recordings and the quality isn't just noticeably better, it's phenomenally better! Also, by recording pink noise on all of the leaders at the time of re-recording, anyone playing back that print on another machine could make themselves a loop out of it and adjust the output of their projector via an EQ to achieve any differences on their playback unit.

Now if you want to get really, really picky about things, encode your prints with dbx Type II noise reduction. You will quickly find that the playback is incredibly close in quality to the DVD without any hiss. Those units are semi-hard to find, but ebay should do the trick.

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John Clancy
Phenomenal Film Handler

Posts: 1954
From: Cornwall
Registered: Jun 2003

posted May 25, 2004 02:24 AM

I'm interested in the dbx noise reduction box now. Hmmmmn.

I believe Pedro's box of tricks already does 24fps sync'. I seem to remember from his web page there are several different versions of the Crystal sync' he produces one of which has 25fps and 24fps capability.

--------------------
British Film Collectors Convention home page www.bfcc.biz. The site is for the whole of the film collecting hobby and not just the BFCC.

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John Whittle
Jedi Master Film Handler

Posts: 791
From: Northridge, CA USA
Registered: Jun 2003

posted May 25, 2004 10:58 AM

For dbx box look for a model 224X-DS which has full encode/decode circuity that allows you to monitor your recording through the device (if you have both record and play heads). But in any event will provide you a major increase in signal to noise ratio and dynamic range which is important working from a DTS or DD 5.1 source. Use the DVD output as Dobly Pro-logic and then run it into the dbx device.

If anyone has a progressive scan DVD player and and a scope it would be helpful to put the signal on the scope and check the video vertical interval (frame rate). It should be 72 fps, I don't know what the GS outputs (1, 2, 3 or what pulses per frame) but if one were working from scratch, a three pulse encoder would phase lock easily and then you'd just need the correction signal to the motor.

Of course you still have to get your machines started in sync, but once you do that they'll keep going until you run out of film or picutre.

John

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