Film-Tech Forum ARCHIVE: Cleaning up prints

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Posted by Ron Curran (Member # 3631) on 04-27-2007, 01:25 AM:

We run films starting either day-and-date or any time from 2 to 13 weeks after release.

A print with DTS is no problem but Dolby Digital prints vary from low error rates (1-4) through to Fail throughout.

We ran a print starting in week 3 where the image was perfect – not dirty or scratched - but the Dolby Digital track was unplayable from spool 2-5. After 5 screenings with FilmGuard we were able to regain most of the DD audio and by the 10th run through the whole film stayed in digital. No discs were available.

Last night we started a print 11 weeks after release and the DD track is showing error rates of 7 and 8 (the manual says the readout goes to 7 then F). Apart from a couple of blips during the first screening, the DD holds in there. Again the image is fine and the second run through showed enough improvement in the audio to trust the DD and not switch to SR.

We also started a print that was quite dirty (10 weeks out) and it has some fine baseline scratches on the far edges (Scope) but the DD is showing error rates of just 3-5. trailers on the front are showing 1-3.

This is one of the frustrations of running older prints. Fortunately, most of them look good on the screen. When a film is more than 5 weeks old, getting and building a replacement is a lucky dip. Without discs, you can’t promote your screening as digital.

FilmGuard does help but it isn’t an instant cure. Perhaps Dolby literature should state that their track can not be guaranteed for more than 30 screenings and used prints must be run with FilmGuard at least twice before advertising them as digital to the public.

Posted by Chris Slycord (Member # 4239) on 04-27-2007, 03:45 AM:

In my experience, one of the first things to be noticeably deteriorated on prints is the DD soundtrack. No matter what happens, eventually it begins to get problems.

And I noticed the error rate of an 8 once as well, which was a surprise.

Though not as big as the time I opened up one of our CP500's and since I wondered why it wasn't playing in digital. The card displayed the following letters in succession: O H E L P. I knew when the card was asking for help that something was clearly messed up. It made me chuckle a bit, though.

Posted by Monte L Fullmer (Member # 2797) on 04-27-2007, 04:01 AM:

..course, the sad thing about DD is where it's located at on the film-inbetween the sprocket holes,- and after the few runs a print goes through, especially from the pressure of the trap and gate and the intermittent shoe contacts (got any worn parts in these areas, by any chance?), that area of the film gets pretty worn, and along with aging LED's, the error rate begins to climb...

Posted by Ron Curran (Member # 3631) on 04-27-2007, 08:09 PM:

Ours is a penthouse reader. I hate to think what results we'd get with a basement reader.

The miracle is that we can (but not always) actually recover DD if we run the print through the cleaner enough times.

The suppliers' solution seems to be to blame the customer. Now we are told that DCI is the answer.

Posted by Ken Lackner (Member # 1002) on 04-27-2007, 08:26 PM:

quote: Ron Curran
The miracle is that we can (but not always) actually recover DD if we run the print through the cleaner enough times.

Indeed, this is one of the benefits of using Film Guard. Not sure if this was one of the purposes it was designed for, or if it's just a positive side-effect, but it does the job, nonetheless. Brad, care to comment?

Posted by Malcolm John Metcraft (Member # 2917) on 04-27-2007, 08:34 PM:

[Wink]

Optical tracks don't seem to have this problem I find them reliable so why change if it works.

Posted by Mike Blakesley (Member # 26) on 04-27-2007, 08:58 PM:

Horse and buggy works just fine for transportation too, but I'll bet you drive a car.

Posted by Alex Grueneberg (Member # 2652) on 04-27-2007, 09:36 PM:

Oo. Burn..

I received print #3 of The TV Set in the other night with enough fresh shoe polish across the reel changes optical and DD tracks to clean up my boots. I thought the DD was totaled for sure but after some gentle work with film guard it came all off, and none of the reels changes dropped out! I was really impressed though. Ran at 3, but I'm sure it will go up.

..Yet for some reason FG still gets smack at my theater.

Posted by Frank Angel (Member # 248) on 04-28-2007, 01:56 PM:

So the assumption is that with an reading of say 2 and 3 the digital audio is where it should be, is there any noticable sound degredation when the error correction is up at 6 and 7? Or is the audio output just either there or not there without and actual descernable sound difference between low correction and high correction rates?

Posted by John Hawkinson (Member # 1135) on 04-28-2007, 05:38 PM:

In Dolby Digital, "2" and "7" sound the same. But at "7", any defect encountered is more likely to result in a drop-out.

I'm a little bit surprised that offline cleaners to address these problems are not more prevalent... (I mean, I know they aren't, and I know that commercially available offline cleaners are stratospherically priced...)

--jhawk

Posted by Chris Slycord (Member # 4239) on 04-28-2007, 08:08 PM:

I'd say it's pretty easy to notice the difference. If a digital soundtrack starts to go and I clean our auditoriums, I'll notice during the credits that the music tends to have a noticeable "warble" in the sound. Though I'll not notice it just walking in and hearing dialog usually.

Posted by Gordon McLeod (Member # 33) on 04-28-2007, 08:30 PM:

the warble is the fact that the delay is not set acuratley and one hears the toggling at high speed between analogue and digital

Posted by Chris Slycord (Member # 4239) on 04-28-2007, 11:25 PM:

Really? Because I've noticed it happen when the processor wasn't showing switching between formats. But maybe it was switching too fast for the processor to show.

Posted by Monte L Fullmer (Member # 2797) on 04-28-2007, 11:35 PM:

quote: Chris Slycord
But maybe it was switching too fast for the processor to show.

Why the usage of opaque tape is terribly wrong for DD presentations..processor can't switch fast enough for the one frame that the encoding can't be read to swing back to optical, thus a nasty 'bloop' in the sound..

Even the usage of 'zebra' tape can be wrong as well if applied incorrectly. Plus, if the location are using that "splicemark" tape and not knowing that the thin yellow side goes over the digital part of the film so the DD track isn't covered,whereas the thick yellow side is opposite soundtrack side...you're asking for problems as well..

Posted by Jack Ondracek (Member # 1466) on 04-28-2007, 11:46 PM:

We stopped using opaque tape years ago. No boot polish, no splicemark, no Zebratape, no post-it-notes... just clear tape. Once you get used to it, finding reels isn't really a problem.

Of course, you know that if you spray the entire film pack with Film Guard, then use an ultra-violet light and yellow goggles, the clear tape shows up immediately.

Learned that one from a CSI episode! [Razz]

Posted by John Wilson (Member # 269) on 04-29-2007, 12:57 AM:

Even the CSI guys use FilmGuard?

Amazing... [Wink]

Posted by John Hawkinson (Member # 1135) on 04-29-2007, 01:03 AM:

Gordon writes, "the warble is the fact that the delay is not set acuratley and one hears the toggling at high speed between analogue and digital".

Chris replies, "Really? Because I've noticed it happen when the processor wasn't showing switching between formats. But maybe it was switching too fast for the processor to show. "

The warble doesn't have to mean high-speed toggling, no. All 4 digital formats (even CDS!) clock themselves based on the speed of film through the digital sound reader -- this is necessary to maintain sound sync. So if the film is unstable through the digital sound reader (particurly a problem with penthouse readers and platter systems), this instability can translate into wow-ing.

You won't hear this on the analog sound, or with a basement reader, because the driven sprockets force the film to constant speed. (Of course you can see wow and flutter in an analog soundhead, but rarely is it as bad as it can be with penthouse readers.)

Of course, this has nothing to do with wear on the digital track. If you have a tension problem and a perfectly printed print and a perfectly aligned reader that reads '1' all the time, you'll still hear the wow.

--jhawk

Posted by Chris Slycord (Member # 4239) on 04-29-2007, 01:58 AM:

That's a nice thought but... we use a basement reader. Ones from component engineering.

Posted by John Hawkinson (Member # 1135) on 04-29-2007, 02:00 AM:

Well, maybe you really do have a wow/flutter problem then.
But it should affect analog and digital both. Well, perhaps digital may be less sensitive to flutter.

Describe more precisely the "warble" you're referring to, the precise conditions under which it occurs, state of the processor, etc.

--jhawk

Posted by Chris Slycord (Member # 4239) on 04-29-2007, 02:21 AM:

I'm bad at describing stuff; my guess is it's probably the delay issue. But next time I see our tech I'll ask him to have a look at it.

Posted by John Hawkinson (Member # 1135) on 04-29-2007, 02:26 AM:

Well, you should get better at it! No time like the present to practice. [Big Grin]

Having the delay mis-set should not result in variation -- it should result in lipsync problems, and maaaaaaybe weirdness at changeovers.

You can try turning off the analog or digital LED so you can guarantee what format you're in and then listen. You can try fiddling with the tension of the running film (apply some more tension with you finger, etc.) and see if you can reproduce the audio defect.

Another possibly issue is the air dashpot on the CE readers need adjustment.

--jhawk

Posted by Brad Miller (Member # 2) on 04-29-2007, 02:30 AM:

Gordon is correct, but I have also seen a wow from SRD and DTS if there is any bounce in the film feeding into the projector. It shows up worse at the end of a reel when running on reels and when using platters with wobbly rollers. Physical tension going into the projector makes ZERO difference on the tracking ability for either format, but bouncing DOES. There should be no real bob up and down of the film in between the platter and projector on the feed side, or if there is some, it should be slow and steady.

You can actually simulate this by bumping the two tension rollers on either side of the sound drum. For a basement reader, bad bearings can produce this effect.

(Also if a print is sitting on 6/7 it can be faulting without dropping to analog at all or displaying an "F".)

Posted by Ron Curran (Member # 3631) on 04-29-2007, 08:00 PM:

Any bounce could be smoothed out by the cleaner before the print enters the DD reader.

Posted by John Koutsoumis (Member # 1855) on 05-23-2007, 07:57 PM:

I have a print of a current film called "Noise" that's shedding a lot since it got here and it is now sitting on 7-8 and constantly goes to F. Does the shedding effect the SR-D track?This was new print. I don't seem to have any problems with SR-D tracks other prints except for the ones that shed a lot.

On the other hand, last week I ran a used season print of "Rabbit Proof Fence" for some school kids and it sat on 3-4 throughout the entire length of the film.

Any ideas? The film "Noise" relies heavily on the (5.1)sound mix and I am investigating how to get the SR-D track back online.

I have PTR rollers and a Christie FC-1 media cleaner but as yet I have neither up and running. I just found the latter in the bottom of an unmarked box.

Posted by Brad Miller (Member # 2) on 05-23-2007, 08:11 PM:

SRD tracks are damaged in one of two ways.

#1 The print is dirty. Prints that are shedding absolutely will cause an SRD track to fail. Just think about it, for SRD to work the system has to be able to see those super tiny dots in between the perforations. Dirt seriously hurts the reader's ability to see the data.

#2 The print has scratches in the SRD track, almost always from gate bands with emulsion deposits on them, but also sometimes from a projector with a rough spot somewhere in the sprocket's film path.

PTRs won't save you. Neither will a dry media cleaner. FilmGuard is your only chance to save that print.

Posted by Chris Slycord (Member # 4239) on 05-23-2007, 08:20 PM:

Also, the dry media by itself will certainly work better than PTRs.

If you notice the PTR review on this site, a print "cleaned" with PTRs ends up looking dirtier than a print not cleaned at all.

Posted by Brad Miller (Member # 2) on 05-23-2007, 08:44 PM:

Actually Chris, no. The dry media won't help the SRD tracks in one bit. By the time the print gets dirty enough to kill the SRD tracks, a dry media pass won't save it.

Posted by Chris Slycord (Member # 4239) on 05-23-2007, 09:26 PM:

I'll have to take your word for it since we've never had prints get quite that bad.

[edit]And while dry media may not help in this situation, from what I've heard PTRs don't help things (in fact, usually hurt things) regardless of the situation at hand. But that's a bit of a tangent.[/edit]

To John:
How long have you had the print in question? It seems odd that you'd get a print that dirty really quickly. Unless, of course, your fellow booth people don't care about keeping stuff clean.

Posted by Cameron Glendinning (Member # 3516) on 05-24-2007, 10:51 PM:

Chris, the print is shedding, ie white powder is falling off it!!!! Some prints do this. Not as common today, but in the past it has been seen far too many times.

Posted by Chris Slycord (Member # 4239) on 05-24-2007, 11:38 PM:

I'm well aware what shedding is.

I've had prints that shed. I've NEVER had so much shedding that your soundtrack gets covered up by the shedding.

The reason I asked about how dirty it was is because I think the whole soundtrack issue likely would've been avoided by cleaning the print regularly.

That is, of course, unless there's something more going on that we aren't seeing.

Posted by Jack Ondracek (Member # 1466) on 05-25-2007, 03:00 AM:

When I book in a co-feature that's run somewhere else for awhile, I try to watch whether I pull an unusual amount of dirt off the print. Everything gets Filmguarded here, right from the first pass, so it's something I watch.

Generally speaking, our prints come in here a lot cleaner than I would have expected. Sure, the pads come up with more dirt than a print that's started out here, but I guess after two or three weeks anywhere without a cleaner, that's to be expected. Still, other than occasionally higher Dolby error readings, I'm not getting anything that looks like it's been horribly abused.

True to its advertising, the Filmguarded prints run quieter and much cleaner. It amazes me that the stuff hasn't become standard booth equipment, just like splicing tape. But then, considering the goop some people use to splice and cue film with, maybe it's not such a surprise.

For sure, if more people just used the stuff, there would be much fewer threads in here about dirty, shedding prints. It's such an obvious fix.

Oh... the motor oil-like stuff a couple chains call "film cleaner"... that's pretty amusing... maybe it shouldn't be. Wonder if it comes (came) from a recently-defuncted supply company???

Posted by Ron Curran (Member # 3631) on 05-25-2007, 10:01 PM:

Reviewers say that “Noise” has a superb soundscape that contributes to the film’s effectiveness. As it only has DD, I am loathe to risk it second run.