8mm Forum: Digital sound on super 8?

This is topic Digital sound on super 8? in forum 8mm Forum at 8mm Forum.

To visit this topic, use this URL:
https://8mmforum.film-tech.com/cgi-bin/ubb/ultimatebb.cgi?ubb=get_topic;f=1;t=000866

Posted by Chip Gelmini (Member # 44) on November 03, 2004, 09:53 AM:

I have just heard that 5.1 sound is available on super 8. Not sure if I understood this correctly. Anyone know about this? Are they already encoded or does a print have to be rerecorded from a digital source? Is all I need is a digital receiver to replace my standard pro logic?

CG

Posted by Rob Young. (Member # 131) on November 03, 2004, 10:33 AM:

Hi Chip,

There seems to be some confusion over this topic which has been discussed in another thread.

I can't resist commenting any longer!

Sorry to disappoint you, but it is just impossible to record 5.1 digital sound on super 8.

5.1 (Dolby, DTS, SDDS etc.) soundtracks are stored in a digital form, whether it be on the 35mm print as optical blocks between the sprocket holes, or a separate hard drive, such as with DTS.

The amount of digital information required is substantial.

The digital decoders turn this information into the analogue 5 channels of sound for the theatre, plus a .1 of deep bass effects.

Super 8 can ONLY carry analoge sound, be it magnetic or optical. You can achieve Dolby Pro-Logic with super 8, as explained in the previous thred by Brad Miller, but this is NOT the discreet channels of sound achieved by 5.1.

I cannot think of any concievable way to store the amount of digital information required on super 8.

Of course, you can sync it up to a DVD, as perfected by the guys at the British Film Collectors Convention, but this relies upon the digital sound on the disc.

Sorry again, but there we have it.

Posted by Daryl C. W. O'Shea (Member # 1) on November 03, 2004, 08:46 PM:

DTS would easily work with 8mm.

Posted by Michael De Angelis (Member # 91) on November 03, 2004, 10:48 PM:

Daryl,

Your post left me hanging, would you care to elaborate on how DTS can work with 8mm?

Best,
Michael

Posted by John Clancy (Member # 49) on November 04, 2004, 01:41 AM:

I suspect a DTS time code would be required on the Super 8 print. Not any chance of that methinks.

Posted by Ricky Daniels (Member # 95) on November 04, 2004, 07:24 AM:

Okay Daryl,
I'm all ears, how we gonna get DTS timecode onto our Super 8mm magnetic stripe?
Regards,
Ricky

Posted by Paul Adsett (Member # 25) on November 04, 2004, 02:04 PM:

Was'nt Brad, our Forum Administrator, working on this a while back?

Posted by Daryl C. W. O'Shea (Member # 1) on November 05, 2004, 03:09 PM:

You don't need timecode on the print to make DTS work. A shaft encoder is all you would need. No different the any large format venue's digital, or even mag, sound system.

Of course getting DTS tracks encoded for 8mm features that aren't identical to 35mm versions would be a whole other battle. Identical versions could simply use the existing 35mm discs.

quote:
I'm all ears, how we gonna get DTS timecode onto our Super 8mm magnetic stripe?

Timecode on the mag stripe could be done too. It'd be no different than the encoding on your credit card, or any other common magnetic data stripe, and could be read with existing mag heads.

Of course optical timecode could be printed where the existing analog optical track is, but again getting that done would be a battle since it would require someone to fund both encoding the tracks (onto discs) AND printing new prints.

In any case, there are trivial methods to do it, but it's only worthwhile if you can get the source material (encoding tracks) to use.

Posted by Brad Miller (Member # 2) on November 05, 2004, 03:23 PM:

Yes, this was something that I wanted to do with a feature in 8mm that had also been released to 35mm, say something like Speed. All that has to be done is the timecode recorded onto track 2. Then using the CP200 interface board, should the dts drop out, the mono track 1 analog audio is still there to keep the show going.

Posted by Michael De Angelis (Member # 91) on November 05, 2004, 10:35 PM:

Daryl,

I'm new to this, what is a shaft encoder? Is that something on the shaft of the projectors motor that keeps the unit in sync with sound?

How is it done with our projectors?

Michael

Posted by John Cook (Member # 203) on November 06, 2004, 12:51 AM:

Brad,

If I read you correctly in addition to the CP200 interface you'd still need the outboard DTS disc player, the balance stripe sync pulse would be used to keep the outboard player in sync with the film print, correct?

Out of curiousity, what does one of these outboard DTS players cost and does it output standard SPDIF (coax or Toslink) at a nominal 48KHz sampling rate? How readily available are the DTS sound track discs to the public?

Regards, John

Posted by Tony Milman (Member # 7) on November 06, 2004, 02:08 AM:

I'm Lost [Frown]

Posted by Brad Miller (Member # 2) on November 06, 2004, 02:10 AM:

Yes you would need the actual dts player (roughly $4500) and the balance stripe would contain the timecode to keep the dts player in sync with the film.

The dts units output 6 straight analog signals. Remember, these are designed for commercial cinema use. You are thinking in terms of home theater.

Posted by Rob Young. (Member # 131) on November 06, 2004, 05:18 AM:

Daryl, all very exciting and let me say now that if I was wrong, I'd be first to eat humble pie!

I'm with the notion of recording time code on the stripe and like I say, I think that is a really exciting prospect with the right equipment, but my initial point was that you can't record the actual digital sound track onto the stripe and use nothing but the super 8 mag. stripe for replay of digital 5.1. The digital sound is stored elsewhere and run, with whatever set-up, in sync with film.

Are you saying you can put the digital sound directly onto the mag. stripe?

Honestly, nothing would make me happier if I was wrong and you are saying you can!

Posted by Brad Miller (Member # 2) on November 06, 2004, 02:11 PM:

Sorry Rob, but you were not wrong. Can't be done.

Posted by Daryl C. W. O'Shea (Member # 1) on November 06, 2004, 11:37 PM:

quote:
Out of curiousity, what does one of these outboard DTS players cost and does it output standard SPDIF (coax or Toslink) at a nominal 48KHz sampling rate? How readily available are the DTS sound track discs to the public?

In addition to the analog outputs Brad mentions, there are also AES (if I remember correctly) digital outputs. You've got to go to analog at some point though, and I can't think of a reason someone with an 8mm setups would want to carry things in digital further than they need to anyway. Then again, I wouldn't be too surprised if someone had a rack of digital processing gear. One guy I know, who runs a pro recording studio, has a digital processing rack setup for his small gauge film's analog sound.

quote:
I'm new to this, what is a shaft encoder? Is that something on the shaft of the projectors motor that keeps the unit in sync with sound?

The other way around actually. It's to keep the sound in sync with the projector (sound is forced to follow the projector speed). Shaft encoders are generally attached to one of the sprocket shafts in a projector. Most output 4 bi-phase pulses per rotation which would be feed to a converter that outputs either SMTPE timecode or DTS timecode directly.

Rob, it sounded like you were ruling out any form of digital sound in your first post when you said:

quote:
Sorry to disappoint you, but it is just impossible to record 5.1 digital sound on super 8.

5.1 (Dolby, DTS, SDDS etc.) soundtracks are stored in a digital form, whether it be on the 35mm print as optical blocks between the sprocket holes, or a separate hard drive, such as with DTS.

Which isn't a very accurate, or at least clear, statement to begin with. You can't store DTS sound on 35mm either. You can however, make DTS sounds work on 8mm the SAME way it works on 35mm. Or you can record the DTS timecode on either of the mag stripes, of course the balance stripe would be sufficient.

quote:
Are you saying you can put the digital sound directly onto the mag. stripe?

quote:
Can't be done.

While in practice that is true, but it's not entirely accurate either. Digital sound could be recorded to a magnetic stripe (people do it every day), but the bit rate on 8mm film would be severely limited by a factor somewhere around 1/10th, making it something you really wouldn't want to do and making an unmarried format like DTS a much better alternative.

Posted by John Clancy (Member # 49) on November 07, 2004, 08:52 AM:

Right, so has anyone got a 35mm DTS setup they can loan me so I can check all this out?

UBB.classic^TM 6.3.1.2