The black hole between you and the final print!

[georgia]

I'd like to begin a post discussing the steps and stages of Post production from the point of the final mix beging Finished, to the 35 mm or Video being Show in a threatre or on DVD. I've noticed that a lot of sound desginers, audio editors, re-recording engineers, have limited or little knowledge of what happens when the final mix leaves your studio. So i'd like to propose a topic on filling in this black hole of knowledge.

So i'll begin. First off.. I'm not entirely sure of the all paths myself. A lot has changed and a lot has stayed the same. We've gone from mono to 7.1 film mixes, from white Leds on camera's to red leds, from film to digital post and even from projection of 35 mm prints to digital downloads and digital cinema.

So my questions for this topic:

How does one print master for DTS? Dolby Digital? Stereo?
What happens to the mix when downmixed to LtRt by Dolby ? by DTS?
What happends to the printmaster at DTS? How does the CD get created?
How does the optical DTS timecode track get created?
How does the Dolby Digital MO disk get transfered to Optical?
How does a QUAD track get created? What the heck is a QUAD track?
How does the quad track get married during the creation of the Internegitive?
Whats an Internegitive?
If the Negitive sound track is B&W and the Picture negitive is Color, what happens to the sound when the internegitive is created? ( if anything )
What is an Interpositive?
When a print is color corrected does thia change the sound?
If a print is over or under exposed what happens to the sound?
How does the final Print get created?
Why does the camera that prints the dolby digital track utilize 96 Leds in a straight line?
How come when you look at a Dolby digital track you do not see 96 clear black or white lines ?
Why does dolby digital use 96 X 96 matrix for each "box" of data on their digital track?
What happends when the Dolby digital track fails? What happens when the DTS digital Track fails?
Why has dolby encoded the LtRt track in the dobly encoder as an AC3 file on the MO?
Why a Red Led over a white Led for playback in threatres. What does this do to my mix?

I have beem asked these questions by other engineers and I have asked a few of these myself...

I have a few of these answers and will try to post them shortly.. But I don't have all the answers by a long shot and I'm tired of not knowing the ENTIRE audio path from end to end in detail.

cheers
georgia

[georgia]

Here's some data...

Dolby Digital uses 96 red leds to create a single line of code on a 5.1 track on a print. ( the red leds are aonther whole issue since we are still dealing with red and white leds in threatres)

The 96 leds work as a single Line, turning on and off as required to print the encoded ac3 data stream. The each line is grouped in grids of 96 lines. There are 4 grids of data (96 lines each) for every picture frame on a 35mm print. The encoded 5.1 AC3 data is shot by the camera directly from the MO disk with no change to the 5.1 audio quality since the MO disk is AC3 encoded upon creation.
If you look at a 35mm print you will find the Dolby digital data located on the left of the optical track between the sprocket holes. There is a DD label in the center of the data block. This block should be consistant in contracts and brightness across the block. The decoder systems, when reading the data blocks will show quality data ranging from 1-6 and F. If the Dolby Digital track is created incorrectly the decoder systems will display the 6 and/or F If this occura the dolby digital track will fail and the audio will fall back to the optical track. 5 and under will work to variing degrees. Obviously we would like to see a 1 or 2 on this data. Note: the LtRt track is also AC3 encoded onto the original MO disk and created during the Quad track negitive or sound negitive process.

Side note: on a 16mm print you can only have mono or DTS 5.1 as you can only print a mono sound track or DTS timecode with NO optical, one or the other

The QUAD track is the 35mm negitive of the sound track consisting of DTS time code, Dolby digital data, SDDS, and LtRt, as required by the project. This is later married to the picture negitive. Once the picture negitive is married to the Quad track or sound negitive as the ccase may be, the print si created.

When the print is approved an internegitive is created from which the print copies are created. So there are a lot of places in which problems with the sound can be injected. It is important , I believe , to understand this path to assure that if a problem occurs you can help to trace the problem to the source and resolve it.



more later.

cheers
georgia

[JKD99]

Hi all
Well, I'll answer the ones I know....

How does one print master for DTS? Dolby Digital? Stereo?

For Dolby Digital and Dolby Stereo Lt/Rt (analog), the Dolby consultant shows up on the stage witn the Dolby DMU unit. They patch the AES outputs of your console (or Audio Interface) into the DMU, and the analog outputs into your monitors. They run pink noise to ensure you're aligned at 85 db. They also need a black burst and timecode feed. You roll the mix, feeding timecode to the DMU, and the 6-track is recorded to the Dolby MO disc. Usually, to save time, you record the Lt/Rt simultaneously. You play back the 6-track to check for any dropouts, and then check the Lt/Rt. Since the Lt/Rt is analog, and does not have the dynamic range and headroom of the digital, you may have to adjust the louder sections to fit into the stereo optical. Also, the Dolby matrix can do some strange things with your audio, such as "hooking", which is when the matrix gets confused (usually by misic) and tries to drag the dialog out of the center channel.

What happens to the mix when downmixed to LtRt by Dolby ?
There's a "smearing" effect that the matrix imposes on the sound, as the LCR isn't discrete anymore. Also, there's no discrete sub, and the surrounds are mono.

How does a QUAD track get created? What the heck is a QUAD track?
A Quad track is a sound optical that carries all 4 sound formate: Dolby Digital, Dolby Stereo, DTS, and SDDS.

When a print is color corrected does thia change the sound?
Color correction is done before the composite print is made, so, no.

How come when you look at a Dolby digital track you do not see 96 clear black or white lines ?
If you look closely at a piece of a composite print, in between the sprocket holes you'll see a tiny Dolby logo. This is the Dolby Digital track.

What happends when the Dolby digital track fails?
The cinema processor automatically switches to the Dolby Stereo track

As you can see, once the MO is sent to NT Audio (or wherever the sound optical is being shot, my knowledge gets fuzzy, and I wouldn't want to post little bits and pieces of info. Don't know nuthin' about the film processing side of it.
Georgia can probably answer all her own questions about DTS, so please chime in! Interestingly, on all the large-scale features I've been on, we've only done the Dolby printmasters. I believe the DTS and SDDS can be created off-site, I'd assume from a drive containing the 6-track, as I've never been on a stage where we said, "OK, now let's do the DTS version" Anyone care to elaborate?

[IO Composer]

Great thread, Georgia. Thanks for writing.
I've done dolby digital and LtRt tracks for film only as I mostly work on independant animations when it comes to working with film, which typically only make it to the festival circuit. However, I have a project coming up that will require all formats due to an expected wider release than just the festival circuit. So my question is: what is required (prior to printmaster) to create SDDS and DTS soundtracks from a mixing and preparation standpoint? Do you have to mix in 7.1 or can you mix in 5.1 and have all of the formats covered? Also, i would like to be able to possibly do a printmaster from my studio rather than rent a stage, so I'm interested in finding out what the studio requirements are to get a DMU in. Do you have to have your studio "certified" by dolby?
-Jamey

[georgia]

SDDS is a dying format. ( well so I hear... ) anyway, if I were doing it i'd mix in 5.1 and leave the Lc and Rc unused unless there is a significant reason for doing otherwise AND there is a budget to do so. If you do mix in 7.1 make sure you check the 5.1 LCRS Stereo and Mono downmixes.

I don't recommend creating a DTS digital 5.1 or LtRt mix from a Dolby MO disk. But, you can dual track during printmastering to a DTS T2 rack and a Dolby DMU. Well, as long as you keep a referee
in the room to keep Dolby and DTS from beating the crap out of each other. ( only kidding ! )

The Dolby DMU will require digital inputs and outputs, the DTS T2 will require analog Ins and Outs.

The problem with dual tracking is making sure your monitoring the Dolby Digital mix but not affecting the DTS mix with the Dolby Mix. You will also have to Quality Control check whichever mix you wern't listening too. And I promise it'll be a pain in the butt.

To printmaster a DTS mix you need a multitrack deck, such as a DA98 / DA88 and the DTS T2. You'll print the 5.1 mix and then the LtRt Thur the DTS T2 rack analog to the DA98. You can use the DTS 5.1 mix, which is unaltered thru the DTS tower ( T2 ) to create a Dolby Digital AC3 MO afterwards by re-running the DA98's.
Dolby AND DTS both require a technician on site to calibrate and to monitor the printmastering. This is included in the package paid by the licensee.

The DTS tower does not do anything to the 5.1 mix other than allow you to monitor and check downmixes. It does do things to the LtRt mix however.

The Dolby DMU AC3 encodes both the Digital 5.1 and the LtRt as well as adding SR so I wouldn't run a DTS mix FROM a Dolby 5.1 mix, but you can run a Dolby 5.1 mix FROM a da98 for DTS. If you do the DTS first, you then run the Dolby digital 5.1 and then run the DTS 5.1 once again from the da98 into the DMU to create the AC3 SR encoded Dolby LtRt.

So, overall I guess i'd set up for DTS and mix DTS thru the T2 and to a DA98. Then the next day setup for Dolby and re-run the mix or run the DA98s.

Once you've completed the Dolby DMU MO it gets sent to the lab. The DTS da98 is shipped to LA where DTS creates the CD. DTS will arrange for the delivery of the T2 Tower and will give your client a DTS ID code. The ID Code is important as the Timecode printing lab for the DTS sync will require this number.
If you've never done a DTS mix in your room, i recommend you get 2 copies of the DTS CD and take one to a local threatre and run the CD without the film to verify your mix. You'll need a DTS Time code disk that runs in the DTS reader and provided code to run the film CD. You might also ask them if you can borrow a CD reader to set up in your studio for a test run to make sure all is in order. I have never had any issues with a DTS mix other than 1 CD being 3db down, but that was resolved very quickly with no issues. But, you don't need to do this... I'm just naturally paranoid when it comes to mix levels.

cheers
georgia

[georgia]

As for being an approved Dolby and/or DTS dub stage. Both have a set of standards online that your room will have to meet. Once you've met these standards, you can contact both companies and arrange for a site visit. If you meet or exceed the criteria and get through their testing and calibration, your good to go.

PS: Dolby and DTS do not "certify" a room they "approve" a room... I guess it's legalese....

Dolby is a bit more stringent that DTS with the requirements. You can mix to a Video Monitor with DTS as long as the room is calibrated to their spec. Dolby requires a minimum distance of 15ft between the screen and the mix position, Microperfed screen, speakers behind the screen, etc...

Dr Sound goes into a lot of this in detail on his room alignment thread. SO i'd rather keep this thread to POST final Mix.

Cheers
georgia

[dr sound]

Jamey,
Instead you can come over to my place and I'll do the work. (Jamey stopped by today to see the room)
What do you think about the room?

[georgia]

mn, hey I want to come over to see youre room! I never get to go to LA... geeze...




cheers
georgia

[IO Composer]

hehe. You'd be jealous, Georgia. It's really, really nice. Fit for royalty, to be sure. The recliner chairs alone are worth the price of admission! Visiting big rooms like Marti's really puts things in perspective; If I ever get too confident in what I'm doing, I just need to walk down the street a few blocks and get put right back in my place

I think I should have rephrased my previous question in that I would like to have the knowledge of what it takes to printmaster in my studio without fooling myself into thinking that I could do a complete job here, because of course I understand that you really can't take it to the "state of the art" in a small room like mine; you really need to take it to a big room with experienced ears if you're trying to compete sonically with the rest of the films out there. However, short of absolute perfection, I believe you can take it pretty far in a well-tuned small room like mine with the right knowledge and gear. I'd like to be able to achieve a reasonably high level of printmaster for projects in which I don't have the budget to involve greater ears and rooms than mine. If I have the money, it's a no-brainer to take it to a room like Marti's and I'm really looking forward to making that happen, both for the quality of my productions and for the opportunity to watch a master in action.

-Jamey

[martian]

Interestingly, on all the large-scale features I've been on, we've only done the Dolby printmasters. I believe the DTS and SDDS can be created off-site, I'd assume from a drive containing the 6-track, as I've never been on a stage where we said, "OK, now let's do the DTS version" Anyone care to elaborate?

Hopefully that's a protools disk - not the MO - I would never want to use AC3 encoded audio to do a higher quality format like SDDS or DTS, having done an A-B comparision of say SDDS to AC3 it's obvious which sounds (much!!) better. I did this with the (late) Les Mckenzie in the stage now owned by warner bros in Thailand. That particular master was made from the same mix as 5.1 but re transferred from DA88 to SDDS.

Not all dolby encoders in Asia have AES in's - I was real disappointed when I saw that- We had to go via the analog outs of the DA88. Dolby uses the Asia area to dump it's older models- I've seen a lot of rather beaten up looking AC3 encoders.... Or maybe it's the same one carted around looking prgressively worse...

Dolby definitely has abitary values regarding rooms.. We built a mix theater that was a nat's whisker off their required ceiling height,though the acoustics were designed to fit the curve and the sound when finished was terrific and true- we were refused approval and forced to visit another existing facility to master -

interestingly it had had a lower ceiling! Ceiling was also concave which according to most acoustic texts concentrate rather than diffuse reflections- A weird flutter echo permeated- maybe due to that ceiling or was it the solid concrete plastered rear wall?? - Room ratio was wrong according to the spec sheet I was given, very long room, maybe less than 1/3rd as wide as long.... and yet was Dolby approved???!!!!

Fortunately we did our mixes in our room and went down there with premixed stems..... Film was nominated for best sound this year....