8mm Forum: "Pedro Box"

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Posted by Osi Osgood (Member # 424) on November 11, 2017, 11:24 AM:

I;ve heard this thing talked about for years, but i still don't know ...

1. Who manufactured it.
2. What does it exactly do?
3. How to use it.

Though artistic, i am not the best person when it comes to high precision stuff, but I'd like to know if I'd want to sync a recording for super 8 off of a DVD or laserdisc.

Posted by Bill Brandenstein (Member # 892) on November 17, 2017, 12:13 AM:

A worthy quest, but sadly is now a tough one.

1. "Pedro" is the pseudonym of Wolfgang Thuille, who used to have a website and built these sync boxes and shipped them everywhere.

2. These made second-sound-system technologies on Elmo GS-1200s and apparently some Bauer projectors work. The European ones would read a 25Hz PAL video signal and output an ESS control pulse that would synchronize a GS-1200 to (probably and hopefully) a DVD in 5.1. The US ones lacked the ability to read a video signal because of the weird 23.976 rate our NTSC video forces us into. Instead, he had a quartz crystal speed generator that would make its own 23.976 pulse without listening to any external input. So a close guess, but technically "wild" sync. These boxes weren't cheap! He also made a simpler one that I bought that takes an audio input and converts them to the square pulse that the GS-1200 syncs to. That allows for a control track to be played from a computer or other device, making use of inexpensive existing gear.

3. Depends on the model of the Pedro Box. Operation varies greatly according to which one.

Hopefully that helps!

Posted by Maurizio Di Cintio (Member # 144) on November 18, 2017, 04:07 AM:

Hi, there. The most basic one (which I own) is capable to output a control signal to the ESS input socket of the Gs 1200 in order to have it run at precisely 16 & 2/3, 18, 24 and 25 fps (quartz lock): this means it can be used to sync to an American DVD runnung at 24 fps (or a Bluray for that matter),no problems whatsoever. And it does not need a video input to generate the reference signal: it generates it on its own

Posted by Bill Brandenstein (Member # 892) on November 18, 2017, 11:18 AM:

Maurizio, there is an even more basic one than what you're describing, and that's the one I have. There is NO internal quartz control; I have to feed it an external audio source with beeps at the correct frame intervals. With what I do in software, it suits me perfectly.

So I believe there are 3 levels to this product:
1) no internal oscillator or control, a simple conversion box
2) internal quartz time generation for reasonably accurate "wild" sync
3) all of the above, plus the ability to "read" a video source (PAL only, I believe)

Now that Pedro has disappeared from the scene, it would be nice if someone would begin to produce #1 again, as any computer with 2 or more audio outs could drive this. And at this point that's pretty much any run-of-the-mill desktop computer.

Posted by Claus Harding (Member # 702) on November 18, 2017, 01:26 PM:

Having seen the box in action, it truly is the closest to "magic" one can imagine: that a silent Super-8 200-footer can get lip-sync sound from a DVD in real-time, with decades separating the technology, is, to me at least, astounding. It would be great if someone took up the mantle and made the boxes again.

C.

Posted by Renzo Dal Bo (Member # 5688) on November 18, 2017, 04:22 PM:

Hi everyone,
I never had any type of Pedro's box, but reading a lot about that and its marvelous features and taking inspiration from a previous project of mine (where you can read about it here), I built a prototype of a sync box with all the characteristics of the old Pedro's box.
Despite it is a home made device, it works very well and it is able to generate sync pulses of fixed frequencies (16,667 - 18 - 23.976 - 24 - 25 fps) to drive the GS1200 with high accuracy through the ESS socket.
My box is based on an Arduino board and it is programmed to start and stop the sync pulses of a frequency, choosen from the above list, pressing a button.
It is also possible to provide the box of a secondary circuitry to generate the pulses at 25 fps, from a video (PAL) analog source.

Renzo

[ November 24, 2017, 11:52 AM: Message edited by: Renzo Dal Bo ]

Posted by Maurizio Di Cintio (Member # 144) on November 18, 2017, 04:29 PM:

Hi Renzo. Having seen some of your achievements, I can only vouch for what you do. Could you make some of these devices for others?

Posted by Renzo Dal Bo (Member # 5688) on November 20, 2017, 05:15 AM:

Hi Maurizio, nice to meet you here.
Yes, of course, I could! But I don't think there is such an interest for a new sync box, as it can be easily substituted by a computer with a proper software.
My box, although full working, is still a raw project .
It would need a tester who own the original box to compare its good functioning. You could be that person!
If there is someone interested in this sync box, before to build other new boxes, I could send you the prototype for testing, if you agree.

Renzo

[ January 03, 2018, 04:32 PM: Message edited by: Renzo Dal Bo ]

Posted by Paul Browning (Member # 2715) on November 20, 2017, 06:22 AM:

Hi Renzo, I have the all singing all dancing pedro box, and the other box of Pedro's to make a comparison, perhaps it might be worth finding out if there is enough interest in the box before you spend time making them, but I could also test it for you in a like for like situation if needed......

Posted by Maurizio Di Cintio (Member # 144) on November 20, 2017, 03:39 PM:

No problems with me Renzo. If/when you want to proceed, just drop me a line via the message service of this forum and I'll send you my home address. Cheers

Posted by Renzo Dal Bo (Member # 5688) on November 24, 2017, 11:45 AM:

Thank you, Paul and Maurizio, for your willingness to test my sync box for Elmo GS1200.
At the moment, my prototype is equivalent to the P1008GS-Q original sync box, but, in addition to the four original frequencies, it allows to sync the projector also to the NTSC frequency of 23,976 Hz.
As soon as I put the prototype in an appropriate "box", I will contact you to organize the comparison test.

Renzo

[ November 24, 2017, 05:13 PM: Message edited by: Renzo Dal Bo ]

Posted by Maurizio Di Cintio (Member # 144) on November 28, 2017, 03:52 PM:

Hello, Renzo. I see you chose to use a battery as power source, instead of the power output supplied by the ESS socket. Considering aging of some components, which might lead to whimisical performance by the original box, this is a good provision.

Are you also planning (or have you planned) to include an external power supply input?

I confess I am very curious.

Later,

Maurizio

Posted by Renzo Dal Bo (Member # 5688) on January 04, 2018, 06:03 PM:

Finally Boxed !!!

It took a bit of time to accommodate all the electronics in a box with small dimensions. For sure more time than to build the prototype. I wanted it was well fitted and rationally arranged.

Maurizio,
at the moment the sync box is powered by a 9V battery, but it is no problem to provide it with a socket for an external 9V DC power supply.

I am sorry for the craft label, I hope it makes to understand how the sync box works. After turning on the "Power" switch, the "Speed Selection" button allows you to select the desired speed, reported by a led. The "ESS Pulse" switch allows to start and stop the ESS pulse signals to send to the GS1200, connected by the DIN plug.

The accuracy of the pulses is very high. For all the speeds, the error is lower than one frame/hour.

Ready for third parties tests!

Renzo

[ January 07, 2018, 06:54 PM: Message edited by: Renzo Dal Bo ]

Posted by Joe Taffis (Member # 4) on January 05, 2018, 09:37 AM:

Renzo, That's very good news! I'm sure many of us are looking forward to seeing the test results [Smile]

Posted by Osi Osgood (Member # 424) on January 05, 2018, 10:44 AM:

What an awesome invention! I'll be curious to hear the results as well! [Smile]

Posted by Maurizio Di Cintio (Member # 144) on January 05, 2018, 12:55 PM:

Hello, Renzo.

I've just received some films to transfer to my NLE for redubbing in Italian and I will have a lot of work for this unit. The film that I will be transferring will provide a visual and time reference to edit and conform the DVD's audio. Needless to say all of this requires the utmost accuracy but I am sure your sync box will handle the task flawlessly. Are you still willing to let me test it?

Posted by Bill Brandenstein (Member # 892) on January 05, 2018, 05:22 PM:

Renzo, congratulations on a great product, and I hope you can sell a good many of them in due time!

Posted by Renzo Dal Bo (Member # 5688) on January 07, 2018, 09:49 AM:

Thank you all for your positive and gratifying comments, but I am walking on eggshelds and here I wish to explain why.
I am only a passionate, just like you, that loves to experiment, above all to understand how the things work. I am not a professional, but only one who likes put his nose in different activitives. So my main target is to satisfy my curiosity and I never thought to gain money about that. When Maurizio asked me if I am willing to build the box for others, I answered positively, because it is always a pleasure to help other passionates when they are in need. To answer those who contacted me private to know if I sell this sync box, I say: "maybe, only if and when I will be sure it properly works".

I have to admit it is very hard to master all the variables of this task, maybe it is impossible. I try to explain myself despite my poor english.
In my project I can calibrate accurately the synch box in way it generates pulses taking, as reference, the crystal built in the Arduino board, so the projector is led by that. When you play separately the soundtrack, with your computer or a DVD player, and you want it to stay in sync with your projector, they take, as time reference, their own built in crystals. All the crystals produce relative time references and not absolute references. However precise, they could be a little different and drift for some reasons (one of these is the temperature). These very very small differences, sometime random, can produce in long times not acceptable differences. For example, an imperceptible lack of one thousandth of second at 24 fps, after an hour, produces an error of 86 frames.
To solve the problem, one simple and safe way is to adopt the same time reference source.
When you play concurrently by a computer the soundtrack and the track with the pulses, they will stay always in sync, because they refer to the same time reference produced by the computer itself.
So you already understand that to aspect a perfect sync for long times in a "wild" sync is almost impossible to achieve.
And, though I have never owned one, I believe also the Pedro's box is not able to keep the projector in sync for long time.
However, what I made to maintain a separate box, just like Pedro's one, and, in spite of everything, to improve its accuracy, is to "tune" my box to my computer or my DVD player. I don't want to bore you telling how, it would be complicated for me here.
Briefly, first I estimate the error and then I modify the program in the Arduino board to compensate it.
Therefore my box is very precise with my equipment, because it's tailored on it, and I always have the possibility to change its program and to adapt it to a new equipment. Usually they are tiny adjustments (some micro seconds).
So, at the moment, I cannot guarantee the same precision with other stuff. For now I would say my box is quite precise, I hope as precise as Pedro's box. This is the reason I asked someone, who have the Pedro's one, to test mine.

Maurizio, you are the man!
I already have your address, but I would like to contact you by phone, please could you send me your phone number private?

Thank you all again

Renzo

[ March 02, 2018, 04:26 AM: Message edited by: Renzo Dal Bo ]

Posted by Maurizio Di Cintio (Member # 144) on January 08, 2018, 03:32 PM:

Hello, Renzo.

PM sent.

Posted by Bill Brandenstein (Member # 892) on January 09, 2018, 11:18 AM:

Renzo, for doing this as an amateur, your results certainly look professional! I'm not sure Pedro's efforts are any better, with possibly one exception: accepting an external input. You're correct that "wild" sync is only trustworthy to a point. Some of Pedro's boxes accepted an external input of a PAL (standard definition) TV signal and the box would output the pulse for 25.00fps to match. Unfortunately, he never offered an NTSC version, so I'm presuming he achieved this with rudimentary electronics.

My Pedro box has no crystal oscillator nor video input. There are two audio inputs only. So it's driven by a standard line-level audio input (RCA) or connector from a Bauer camera-type system. If I create a series of short beeps and play it into this Pedro box, the projector can be adjusted to match the frame rate perfectly, and then there is no drift.

Some people have had success creating an ESS pulse directly from their computer sound card, but mine didn't work.

Posted by Paul Browning (Member # 2715) on January 09, 2018, 12:04 PM:

Bill I have the more sophisticated box by pedro, and any fps can be dialled in and locked crystal sync, he has preset the common fps already including the NTSC, with this box its an added feature for you guys across the pond, and on in some cases dvds in the uk that are imports, all that said a very good addition.

Posted by Bill Brandenstein (Member # 892) on January 09, 2018, 04:37 PM:

Agreed, Paul, but that is still technically "wild" sync. Which can work very, very well. But nothing beats having a pulse control track that starts, stops, and stays locked frame-accurate with the audio for the full duration. To make "wild" sync work, not only do your audio source and Pedro box need to drift very little from one another, but you also have to be a bit lucky and hit "start" manually at just the right instant - or adjust the projector later by eye.

Posted by Paul Browning (Member # 2715) on January 10, 2018, 01:21 AM:

There is a disc Bill sent with the kit with the beeps on to automatically start the projector, there is also a manual giving the full details of different setups, most of them I would think, but its a little difficult to understand in parts but nothing is missed, Pedro was obviously doing this for a living or an incredibly keen amateur......

Posted by Renzo Dal Bo (Member # 5688) on January 11, 2018, 06:06 AM:

Hi
I have already contacted Maurizio to arrange a deep test.
I will ship my sync box to him, who will judge if it works like Pedro's one, dubbing a feature film. I know he is a master in this kind of job.
Nevertheless in order to improve my project, I am looking for any information regarding the old boxes. In particular I wish to ask you some good photos of the sync boxes you own, or any kind of instruction manual about that. I need to understand how they works, because I will try to reproduce their feautures in my project. Thank you all.

Renzo

[ January 11, 2018, 11:52 AM: Message edited by: Renzo Dal Bo ]

Posted by Bill Brandenstein (Member # 892) on January 18, 2018, 12:08 PM:

So here's what I have. This has to be the simplest of Pedro boxes:

It has an input on the left side for 9V DC power and I had to supply my own "wall wart." Otherwise, it's very simple: you have audio waveform inputs either into the Bauer DIN jack, or the RCA jack. As you see, Pedro labelled it for -10dB audio with 1000Hz cue beeps, so this box has no timing ability of its own. All it does is convert an audio trigger into the square pulse read by the GS-1200.

He sent a CD with my box with 1Khz pulse tracks at various frame rates, although I know now that some of the timing wasn't perfectly correct. Any consumer line-level audio device can thus play into this device, and if the level isn't hot enough, the green LED doesn't illuminate. Under normal operation, the LED pulses once for each trigger pulse it "hears."

So I ended up making my own control tracks with 1KHz "beeps" about 10ms long, then an appropriate length of silence. At 48KHz (which is what all DVDs use) a framerate of 23.976 corresponds neatly to a beep for every 2002 audio samples. Lots of other options work also, and I have quite a few different files for different frame rates. They can be shared!!!

So you can make a control CD of a mono track with the pulse on one channel and the audio content on the other. I've "added" sound to silent prints this way. But most often I use a computer. Almost any Windows office computer now has audio on the motherboard with multiple outputs, and as long as you can set the driver to use them independently, you're good to go. Any audio software that handles more than one track and file at a time can be used. So you send a pulse file to one output hooked up to this Pedro box, and the other output to whatever you hear your sound through. It takes two pulses to bring the projector up to speed, so all of my ESS sessions have two pulses before the "Start" frame cue. As mentioned before, a Dolby Digital SPDIF-wave file will play perfectly over a digital connection in this manner while a pulse track plays out of an analog headphone jack, but it requires Windows XP and Adobe Audition 3.0 to keep the SPDIF data intact and undithered. Of all the Adobe / Cool Edit products, that's the only version that can pass an unaltered bitstream. I've not tried this with any other software.

It's also important to note that whatever speed the trigger cue file is made for is matched by the projector settings. The Elmo GS-1200 has speed and level controls for the pulse, and a little meter for the latter. If you have a pulse playing at 24 fps and the projector is set to 18, or rates match but the speed control is bumped much either way, the meter will dance around most unhappily. You can run and lock any speed within the projector's range so long as you match the projector's controls to your ESS "playback" so the Elmo "knows" what to expect. The meter sits still and stable when it's done right.

Posted by Renzo Dal Bo (Member # 5688) on January 30, 2018, 05:54 PM:

Thank you very much Bill!
a very detailed description in how your sync box works.
Now I have another task: I have to make compatible the 1000hz input sync signals to the output ESS.

Meanwhile waiting for Maurizio's deep test results of my crystal sync box, I tried to realize another box to keep in sync my GS1200 with a video PAL signal.
I know this is not an innovation, but I would like to input both boxes' features in a single box.
This box is provided of an analogue signal input socket, where you can connect any PAL source (as DVD, VHS, Blu-ray and LD players).
The box also has an analogue signal output socket for monitor. I connected it here to a 4.3-inch LCD monitor, taken from a car rear-view system.
This kind of box don't provide a "wild" sync, but a perfect sync, since the projector is driven from the same sync signal of the PAL source.
It is also useful to re-record the digest films. the box can be connected to a PAL camcorder so it is possible to record by that, in perfect sync, the projected film at 25 fps. The recorded film can be transfered to a computer to edit it with the new soundtrack. Then it is possible, if the computer is provided with an analogue output, directly record the film with the GS1200 in perfect sync during the video replay.

[ January 31, 2018, 02:27 AM: Message edited by: Renzo Dal Bo ]

Posted by Maurizio Di Cintio (Member # 144) on January 31, 2018, 01:13 PM:

Hello!

Renzo's devices arrived a few days ago and I have already tested them, in terms of how compatible they are with the GS 1200. The first tests show they are 100% capable of driving the GS 1200 in perfect consistent run at either 16(6), 18 24 and 25 fps. The control gauge on the projector, after fine-tuning, remains "nailed" in the center position throughout the operation (which in this case was to transfer all the reels of "Ben Hur" on my computer for redubbing). It might be of interest to learn that such fine tuning was slightly different on the three GS I used for the tests, but in all cases it was veery limited: which means Renzo's devices need a fine tuning very close to Pedro's ones. The final tests will be to see if there are any drifts during the final transfer of the sound from the computer to the film's soundtripes but based on experience (past and present) I would anticipate there should be no problems whatsover in fact I am very confident....

Stay tuned!!!!

[ January 31, 2018, 02:35 PM: Message edited by: Maurizio Di Cintio ]

Posted by Thomas Knappstein (Member # 6134) on February 08, 2018, 08:49 AM:

Hello at all!
Here are some Pictures of my own made starting and Impulse Box for synchronising the GS1200 with a DVD Player.
My own made Sound DVD´s have a Beep 7 Frames before Picture Start. When the Beep is comming a Relay swiched a Timer on and 7 Frames later the Impulses are on the Elmo and he starts perfekt. With the Pot on the Box I can adjust the Time when the Elmo is starting after the Beep on the DVD.

Posted by Maurizio Di Cintio (Member # 144) on March 01, 2018, 04:01 PM:

Hello, everybody. Just a little update on the testing phase mentioned several posts ago in this thread. I am glad to say that after extensive usage of Renzo's device, my GS 1200 ran perfectly locked at 24 fps.
The test entailed redubbing in Italian a Kempsky print of Ben Hur (8x180 reels!); because it had been re-edited as opposed to the original spool breakdown (based on 120m lengths), I had to acquire each reel on my NLE system in its entirety so as to be able and compare it to the video source I took the sound from looking for misisng frames which would have caused loss of sync; the final sound transfer from computer to film stripes showed the projector's speed was 100% consistent with the previous phase of capture. So well done, Renzo! I for one can't wait to buy one of your boxes to use as a spare to my "Pedrobox".

Posted by Renzo Dal Bo (Member # 5688) on March 05, 2018, 01:26 PM:

Wow Maurizio!
these are very good news, for me and maybe for those who contacted me private to know if I am willing to build other sync boxes for Elmo GS1200!
Since your expertise is very thorough in redubbing super8 films, now I haven't any dubt about the functionality of my sync box.
When the prototype will come back, for sure the first built new box will be yours.
Thank you so much for your willingness shown to deeply test my box.
I am going to open a new thread asking if other forum members are interested about the box.
Thank you again.

Renzo

Posted by Maurizio Di Cintio (Member # 144) on March 06, 2018, 05:03 AM:

My pleasure.

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