Film-Tech Forum ARCHIVE: 6 Track Magnetic vs 6 Track Digital

my profile | my password | search | faq & rules | forum home

»	Film-Tech Forum ARCHIVE » Operations » Film Handlers' Forum » 6 Track Magnetic vs 6 Track Digital (Page 2)

This topic comprises 11 pages: 1 2 3 4 5 ... 9 10 11

Author

Topic: 6 Track Magnetic vs 6 Track Digital

Tom Petrov
Five Guys Lover

Posts: 1121
From: El Paso, TX
Registered: Jan 2003

posted 12-29-2010 01:52 AM

quote: Sam D. Chavez
IMHO, you really do come off as a total jerk if this matters to you. Thoughtless and mispelled posts do not earn much respect.

Please don't take things the wrong way. I am glad you responded. I was looking for some of what the older fellas had to say. I was wrong in other threads on my opinion of 70mm and that is why I am asking these questions.

Again, thanks for responding! Didn't mean to offend.

quote: Bobby Henderson
With either digital or analog audio sources, the sound system itself plays a giant part in determining audio quality.

I agree with you. But from what I understand, if you play either digital or analog on a well equipped sound system, you are not likely going to hear the difference.

| IP: Logged

Monte L Fullmer
Film God

Posts: 8367
From: Nampa, Idaho, USA
Registered: Nov 2004

posted 12-29-2010 04:07 AM

For Tom and his curiousity on 70mm (and my apologies on the owner of this clip to whom I can't remember the name...)

-Monte

| IP: Logged

Damien Taylor
Master Film Handler

Posts: 493
From: Perth, Western Australia
Registered: Apr 2007

posted 12-29-2010 04:13 AM

To make things even more confusing, as well as magnetic striping applied to the actual film and read by the projector, you can also have magnetic full-coat film run separately but interlocked on a dubber.

quote: Sam D. Chavez
mispelled posts

E might be a SL for Tom, Sam. Terms of affection may have also transposed badly.

| IP: Logged

Tom Petrov
Five Guys Lover

Posts: 1121
From: El Paso, TX
Registered: Jan 2003

posted 12-29-2010 04:39 AM

quote:
For Tom and his curiousity on 70mm (and my apologies on the owner of this clip to whom I can't remember the name...)

-

-Monte

Thanks Monte. Much appreciated! This is valuable information.

Now, in absence of a magnetic track. What would be in place on the print? Play Time and 2001 looked similar as they had something printed there but not exactly the same.

Also, are there four tracks there? Or is it just the outside of the frame?

quote:
ou take 6 track mag audio from a 70mm print and it will blow away any digital reproduction since the encaptured wavefrom on those magnetic tracks are so spread apart due to the film speed of 20ips going across those magnetic headstack reproducers.

The older folks that I have talked who come into my store always remember the advertisments of Dolby when we talk about 70mm. Most are fond of the sound. Also, everyone remember where the theatre was.

| IP: Logged

Mark J. Marshall
Film God

Posts: 3188
From: New Castle, DE, USA
Registered: Aug 2002

posted 12-29-2010 04:59 AM

Basically, the thicker mag stripes outside of the sprocket holes each hold two tracks. The thinner stripes inside of the sprocket holes each hold one track.

Which track goes where is a whole other discussion as there are several different mag formats. Some have five channels across the stage, some have stereo surrounds... There was a discussion here recently on which 70mm titles had which format.

To answer your question on what appears on 70mm when there is not mag striping, there is a DTS time code running along the print next to the sprocket holes on one side. This is picked up by a 70mm version of the DTS reader and sent to the DTS unit exactly the same way a 35mm DTS reader does.

For what it's worth, there was another 70mm sound format back in the early 90s called CDS which printed six track digital audio directly on the film in the place of the magnetic stripes. CDS existed on 35mm also and was printed in place of the analog track. That format had a VERY high bit rate compared to Dolby SRD and even DTS, but it didn't last very long, and it's doubtful that any theaters still have the equipment for CDS laying around. Nor are there going to be many prints left. Even if there were, I don't think many would have the nerve to run it. It's pretty much dead. Do a search here if you are interested. There are plenty of threads about CDS here.

quote: Bobby Henderson
Dolby SR magnetic has a wider dynamic range than 16-bit digital. But it doesn't have a greater dynamic range than 24-bit digital.

Bit word length is one quality factor with digital. Sample rate is another.

Thanks for clarifying that, Bobby! And thanks to everyone who filled in the blanks on the other 70mm SR titles! [Smile]

quote: Darryl Spicer
I think he may be referring to the full coat magnetic on 35mm base used in Imax theaters. Full coat magnetic 35mm was also used on Cinerama and I think it had 7 tracks of sound.

It's also used on very early screening prints if I'm not mistaken. When directors bring their work out to show to critics or at film festivals, sometimes a 35mm full coat mag print is synced with the print that has the picture... as there is no sound track on the film yet.

| IP: Logged

Gordon McLeod
Film God

Posts: 9532
From: Toronto Ontario Canada
Registered: Jun 99

posted 12-29-2010 07:10 AM

Full coat mag had many different track configurations
4 track striped 35mm prints had a small track area than 70mm tracks especially the surround track so a control tone was used on some titles to turn it off (in effect act as a noise gate) The only 4 track i handled with NR was Yentel with A type on it
Also there were what was called cinestage prints that used perspecta sound control tones on the surround track to give L R and back surrounds
Also Quintaphonic used QS matrix on the L and R track to do a Ls and Rs surround track

| IP: Logged

Robert Throop
Master Film Handler

Posts: 412
From: Vernon, NY USA
Registered: Jun 99

posted 12-29-2010 07:25 AM

quote: Tom Petrov
I am wondering if it is worth it to make it Ottawa for the 70mm festival.

Will there be another 70mm festival in Gatineau this year?

| IP: Logged

Michael Barry
Jedi Master Film Handler

Posts: 584
From: Sydney, NSW, Australia
Registered: Nov 1999

posted 12-29-2010 08:06 AM

I could be wrong, but I would think that given sufficient encoding/decoding resolution a digital soundtrack should be indistinguishable from a magnetic soundtrack in double-blind tests using the same source material for both media.

| IP: Logged

Mark J. Marshall
Film God

Posts: 3188
From: New Castle, DE, USA
Registered: Aug 2002

posted 12-29-2010 09:03 AM

You're probably right, Michael. Except that those encoding/decoding resolutions do not exist in the cinema film sound processors today with the exception of possibly lossless DTS. Unfortunately that only seems to be in use in special venues.

| IP: Logged

Bobby Henderson
"Ask me about Trajan."

Posts: 10973
From: Lawton, OK, USA
Registered: Apr 2001

posted 12-29-2010 09:37 AM

Unfortunately, for film-based presentations in standard movie theaters lossy compressed digital (DD, DTS, SDDS) is still the norm. The DTS-XD10 and XD20 processors can play uncompressed audio, even in 24-bit 96kHz resolution and up 8 channels of it. The systems can be modified to add more channels of audio. That capability is going unused. If you want uncompressed audio you typically must visit a digital cinema equipped installation to get it.

quote: Mark J. Marshall
CDS existed on 35mm also and was printed in place of the analog track. That format had a VERY high bit rate compared to Dolby SRD and even DTS, but it didn't last very long, and it's doubtful that any theaters still have the equipment for CDS laying around.

I was pretty shocked when I finally learned the actual bit rate for CDS, around 6 million bits per second. I always assumed CDS ran at a lower bit rate. Considering the state of CCD scanning technology in 1990 it's amazing CDS could even work at all. Dolby Digital and SDDS had plenty of problems early on and those systems had much larger data spots on the film prints and lower bit rates (especially Dolby Digital) compared to CDS. The film readers could reliably see only so small a "digital" pixel recorded onto the film print.

I don't know how many CDS prints still exist; it would be a shame if all the 70mm CDS prints of movies like Dick Tracy or Terminator 2: Judgment Day have been trashed.

It would be interesting to see how the system could work with a new, custom built film reader using the latest technology. It probably wouldn't take too much programming work to modify the firmware in something like a DTS-XD20 to where it could understand and process the CDS data. Lawyers and patent issues would be the biggest obstacle for such an effort to go anywhere.

| IP: Logged

Sam D. Chavez
Film God

Posts: 2153
From: Martinez, CA USA
Registered: Aug 2003

posted 12-29-2010 10:38 AM

The basic problem with CDS is the optics had very low depth of field so any mechanical problem with film would put the image out of focus; even a little chad of splicing tape.

If you can't read the data, you're screwed, and there is no back up.

Oh the irony of misspelling the very word while being critical of others. I looked closely to avoid this, but it got my me. In my defense, spell check stopped working on both of my laptops.

| IP: Logged

Gordon McLeod
Film God

Posts: 9532
From: Toronto Ontario Canada
Registered: Jun 99

posted 12-29-2010 10:47 AM

small correction yentyl was dolby aNR but Tommy was DBX
There were 35mm Atype mag prints for Logans Run but i didn't handle it
Also Earthquake and Midway used DBX on the magtracks for some of the sensuround prints

| IP: Logged

Sam D. Chavez
Film God

Posts: 2153
From: Martinez, CA USA
Registered: Aug 2003

posted 12-29-2010 10:57 AM

The Sensurround system used DBX on the optical prints as well.

| IP: Logged

Jack Theakston
Master Film Handler

Posts: 411
From: New York, USA
Registered: Sep 2007

posted 12-29-2010 11:53 AM

Just throwing in my two cents, but some of the 3-track fullcoat stuff that I've heard are nothing short of incredible (particularly when you consider that the oxide has held up as long as it has).

| IP: Logged

Bill Gabel
Film God

Posts: 3873
From: Technicolor / Postworks NY, USA
Registered: Jan 2002

posted 12-29-2010 12:02 PM

quote: Mark J. Marshall
I think the only 70mm six track SR print was Star Trek 4

Some of these 70MM prints had Dual Inventory of Dolby A & SR prints at depots. Some markets played the film in Dolby A and other markets got Dolby SR prints. Some theatres had to rent extra Cat. 280 cards for their engagements.

1986
Star Trek: The Voyage Home (Dual)
1989
Lawrence of Arabia
Indiana Jones and the Last Crusade (Dual)
Star Trek: The Final Frontier (Dual)
Black Rain (Dual)
Born on the Fourth of July (Dual)
1990
Gremlins 2: The New Batch (Dual)
Days of Thunder (Dual) plus CDS
Fantasia (Dual)
The Godfather Part 3 (Dual)

1991
Spartacus
The Doors

1992
Aliens 3
Hoffa (Dual)

1993
Gettysburg
In the Line of Fire (Dual)
Cliffhanger (Dual)
Last Acton Hero (Dual)
Geronimo (Dual)

1994
True Lies
Miracle on 34th Street

1999
TRON

The last 6-Track Full Coat Dolby SR print I ran was "There Will Be Blood".

| IP: Logged

All times are Central (GMT -6:00)

This topic comprises 11 pages: 1 2 3 4 5 ... 9 10 11

Printer-friendly view of this topic

The Film-Tech Forums are designed for various members related to the cinema industry to express their opinions, viewpoints and testimonials on various products, services and events based upon speculation, personal knowledge and factual information through use, therefore all views represented here allow no liability upon the publishers of this web site and the owners of said views assume no liability for any ill will resulting from these postings. The posts made here are for educational as well as entertainment purposes and as such anyone viewing this portion of the website must accept these views as statements of the author of that opinion and agrees to release the authors from any and all liability.