Dolby Facility Approval Requirements

[jacobfarron]

Studio Approval Requirements
For Mixing Commercials and Trailers
Dolby Theatrical Formats

(Rev 13, June 2008)

(Thanks to danijel for the update)


6.0 Technical Requirements for Studios to Obtain
Dolby Certification

6.1. The first essential requirement for the dubbing theatre is to monitor Dolby
mixes correctly, as well as play your own and other studios' printing masters
and optical soundtracks. To this end you will need to install a Dolby cinema
processor type CP650S1. The CP650S will provide analogue and digital
optical replay, Surround-EX decoding, matrix decoding, full equalisation2 for
loudspeaker calibration on all 7 channels, surround delay and master monitor
level control. The CP650S uses AES/EBU digital inputs and analogue, digital
or analogue cross-over outputs.

6.2. Optical replay of both the analogue and digital optical track is required for
foreign version and original feature mixing to allow the studio to match the
original recording, or to check the quality of an “Answer Print”. This will require
a solar cell and bracket assembly for analogue replay, as well as a Cat. No.
702 or an approved Dolby Digital reader to be added to the projector or sound
follower. The sound follower or projector must be able to run in synch with the
studio recorders.

6.3. The screen and surround speakers and amplifiers must be capable of
providing a frequency response to ISO2969 and, with the requirements of
Dolby Digital in mind, must be able to provide an SPL of 105dBC for peak
levels, after acoustic calibration, without distortion.
Theatre type speakers (pressure drivers with suitable horns) will be required in
medium to large rooms and these should have electronic crossovers.
Appendix A gives further guidance.
Bass management systems are not suitable.

The Dolby Studio Approval Calculator should be used to verify loudspeaker
and amplifier performance capabilities.
Suitable test material is available to check monitor headroom capability (“Jiffy”
test film tone sweep test and a pulsed short duration 0dBfs pink noise test).
Please note that Dolby level pink noise, 85dBC, equates to around -14dBfs.

6.4. The screen speakers must be at a height to give good coverage in the mixing
and listening area. When projecting a 2.35:1 picture the left and right speakers
will be inside the edge of the picture area and provide a 45° angle ± 5° with
the mixing position. If masking is used this must be of the acoustically
transparent type. We recommend that the mixing position be placed 2/3
back from the screen and require that the screen is at least 5 meters from
the mixer. The studio area will be greater than 45 meters square and room
volume will be greater than 150 cubic meters. We will allow some small
deviation to these requirements if, in our opinion, the proportions of the room
and equipment layout are spoilt in order to comply. Room ratios will be within
the shaded area shown in Figure 1 below and ideally close to the straight line.



6.5. The acoustics of the mixing room must conform to the acoustic characteristics
shown in Figure 2. The reverberation time should ideally diminish and show no
reversals with increasing frequency.



6.6. Ambient noise levels must not exceed NC-25 as measured according to ISO
9568 Background acoustic noise levels in theatres, review rooms and dubbing
rooms.

6.7. Two track only “Printing Masters” must be supplied SR encoded for transfer to
optical sound negative on RDAT, Hi-8 (DTRS) or as .wav files. Dolby Digital
“Printing Masters” (6 track and 2 track) will be recorded on a Dolby Digital
Master MOD (Magneto Optical Disk) within the Dolby Digital Encoder for
transfer to optical negative. They must also be recorded to .wav files or Hi-8
(DTRS) tape. Some customers may still request them on 35mm magnetic film
with SR noise reduction.

6.8. Mixing consoles must have a minimum of 32 channels providing full
processing such as gain, EQ, dynamics and pan. The console must provide a
minimum of 24 professional grade faders at least two panoramic controls to
move sounds between at least four channels and preferably six. There must
be a minimum of 8 group outputs. If the studio intends to mix big budget
original productions the above will need to be significantly increased.

6.9. The monitor section of the console must provide PEC/DIR (direct/replay)
switching for 8 signal paths and a 16x8 summing monitor matrix to provide
correct monitor routing during pre-mixing. It must allow individual solos and
mutes of source and monitor channels. If the studio intends to mix big budget
original productions, the number of PEC/DIR switches and matrix inputs will
need to be significantly increased. Virtual (internal) as well as external
solutions are acceptable as long as the user interface is dedicated to this
function.

6.10. The DMU and MME encoders have AES/EBU digital inputs. A Dolby or third-
party ADAC may be used for interfacing the encoder to analogue consoles, but
in order to enable full and correct functionality of the encoder, any third-party
ADAC must comprise:

• 8 channels of analogue to digital and digital to analogue conversion.
• A conversion from the studios analogue level to -20dBfs. Normally this
would be 0dBU or +4dBU equating to -20dBfs.
• Headroom of 20dB above the analogue reference level.

Converters not meeting the above specifications will not be accepted. If in
doubt please advise us the make and model number intended.

A suitable safety limiter on the input to prevent hard clipping at levels over
20dB above reference is not a requirement but is a valuable addition to the
specification.

6.11. Level standardisation at –20 dB below MSB or clip in the console main outputs
and recorders is essential. You may wish to check with the manufacturer that
digital and line levels conform to accepted standards i.e. +4dBu or 0dBu line
level for –20 dBFS internal console level and that the meters read –20 dB.

6.12. For synchronisation, the Dolby encoders require time code and video
reference signals. The DMU can also work with biphase (a 240 or 48 pulse per
frame bi-phase signal for a 24 frame per second rate). The studio must ensure
they can supply the appropriate synchronisation signals prior to digital
mastering.

6.13. Video projection must provide an image that when projecting a film made in an
aspect ratio of 1.85:1 (flat) or 2.35:1 (scope), covers the width of the screen to
at least the outer edge of the left and right screen speakers. Reflected light
from screen (measured at mixing position) must be at least 12fL, and the pixel
resolution of the projector must be a minimum of 1920 x 1080. Processing
delay must be known and compensated for by a suitable timecode offset to the
video replay device. If in doubt, please provide us with specifications and we
will determine suitability.

[dr.sound]

Geert,
THIS SHOULD BE A "STICKY" !!! thumbsupthumbsupthumbsup
Somebody asks about this all the time.

Nice post Jacob!thumbsup

[postprosound]

This a great! It makes dolby approval seem very attainable. For those who my not be interested, or are not in the right position, i think that it's a good model for facilities design. If only taxes were this simple.

I do have to ask:

What's said on the chart mentioned in section 2?

Is this it? Are there other requirements that are not here stated? As an example, nothing is mentioned as to room treatment, rt60 rates, or other possibly necessary equipment. (obviously, you'd have the room treated, etc, but what is dolby looking for, technically speaking?)

Thanks jacob for posting, and i'd like this to be a sticky as well! (I took the liberty of placing this on the DUC as well)

[jacobfarron]

It DOES make it sound attainable. I spoke with Steve at Dolby in NY about building a mix theater, and the information I listed above is the only specific requirements he had. There were no mentions of an RT60 requirement for approval. However, I do believe if a Dolby consultant came to tune the room and it sounded completely different than all of the other dub rooms, the facility may run into trouble.

The only place I have found Dolby recommending ideal room acoustics is in the Dolby Multichannel Music Mixing pdf. I do not know if these numbers carry over into TV Post sound. However, in the appendix it seems that Dolby has simply copied these numbers from AES, EBU, and ITU recommendations. These are also almost identical to THX recommendations I have seen.

3.1.2 Acoustics
Early Reflections
Any early reflections (within 15 ms) should be at least 10 dB below the level of the
direct sound for all frequencies in the range 1 kHz to 8 kHz [6].
Reverberation Field
Reverberation time is frequency-dependent. The nominal value, Tm, is the average of
the measured reverberation times in the 1/3-octave bands from 200 Hz to 4 kHz and
should lie in the range: 0.2 < Tm < 0.4 s. Tm should increase with the size of the room;
the formula in Table 3-2 is a guide.



Reflective and Absorbent Surfaces
Large flat reflective surfaces should be avoided in the mixing environment.
Placement of doors, control room windows, and equipment should be considered with
speaker placement and aiming in mind. A combination of diffuse reflectors and
absorptive materials should be used to achieve a smooth RT decay time within the
specified range shown in Figure 3-1.
Again, it is recognized that these values may not be achievable in some installations,
but is recommended that the room be measured using a real-time analyzer and that
architectural solutions (wall treatments, bass traps, room reorientation, and so on) be
utilized first to achieve the recommended values. A mixture of diffuse reflective and
absorbent surfaces, applied evenly to the whole room, aids in creating an acceptable
reference listening condition [12].
Only after considerable effort has been made using architectural solutions to smooth
the room response should equalizers be introduced into the monitor chain. See
Section 4.2 for more information on room equalization.

Background Noise
The listening area should ideally achieve an NC rating of 10 or below with the
equipment off, measured at the reference position. A studio with equipment such as
video projectors, video monitors, and other ancillary equipment powered on should
achieve a rating of ≤ NC 15.
Any background noise should not be perceptibly impulsive, cyclical, or tonal in nature.


NR 10 or NR 15 may be hard to realize in a practical manner in some installations, in
which case, every effort should be made to identify the loudest noise sources and
correct as appropriate. The most common noise sources and possible remedies include:
• HVAC systems: Increase the surface area of the supply air vent. Separate or float
all mechanical connections between high velocity or rumbling motors and ducts
and the listening room.
• Equipment: Contain computers and other equipment with loud fan noise in noise
attenuating, ventilated cabinets.
• Doors and windows: Make sure all the doors and windows are aligned properly
and form a seal when closed. Adding a second window or door, with air space
between it and the original, can reduce unwanted noise considerably.
Other sources of problem noise may need to be addressed. Every effort should be
made to approach the recommended values shown in Figure 3-2.

Once again, THESE ARE NOT REQUIREMENTS FOR APPROVAL. They are the only recommendations I have found Dolby to make. Furthermore, they are general guidelines based on AES, EBU, and ITU recommendations.

If someone knows that these figures are not applicable for Cinema/TV, etc please let me know.

JBL also lists acoustic considerations specifically for Cinema, based on Lucasfilm recommendations. http://jblpro.com/pub/cinema/cinedsgn.pdf

[Eric L]

Nice work Jacob.

Make it a sticky please.

[ggegan]

I thought it was odd that I had never heard of this certification program before, and as it turns out the Dolby web site states that the program is not available in either the USA or Japan. Maybe they've ceded the service to THX here in the US.

In any event, the recommendations seem to be pretty standard for the industry, at least here in Hollywood, and it's very convenient that they are all here in one document, even though it appears to be a pretty difficult tech paper to find. I searched the web for it and couldn't find it anywhere, even on the Dolby web site. Can't figure out why. It seems like a good resource.

[jacobfarron]

There is no mention of this on the Dolby site. This is not the "premiere" certification program. Since Dolby approval is required before a studio is allowed to make 35mm printmasters with Dolby encoding, I have no idea why this information is so hard to find.

[Steven1145]

In fact you receive the document from Dolby when you call them up and enquire about certification. I had not posted it as I was not sure that Dolby was OK with that, seeing that it's not easily available for the general public as you have all pointed out.
In our case, we have chosen not to run for Dolby certification as we chose to buy a 2k projector and do not have 35mm playback.

It should be noted that the room dimension chart is a guideline. I'm sure rooms that are not exactly "on the chart" could be certified if they sound good.

Steven

[Geert van den Berg]

Originally Posted by Steven1145

In fact you receive the document from Dolby when you call them up and enquire about certification. I had not posted it as I was not sure that Dolby was OK with that, seeing that it's not easily available for the general public as you have all pointed out.

I agree, if they don't want this to be online, they can contact me and I'll take it off.

But still, then I would make some sort of summary of the whole.

I think anyone benefits from these kind of specs.

[Steven1145]

Geert, I totally agree with you. Making this information difficult to find just makes everyone lose a lot of time in guesswork. In any case there are'nt any terrible trade secrets included in the document, and Dolby do not make you sign an NDA when they send it to you so hey!... Why not?

[dr.sound]

Originally Posted by Steven1145

In fact you receive the document from Dolby when you call them up and enquire about certification. I had not posted it as I was not sure that Dolby was OK with that, seeing that it's not easily available for the general public as you have all pointed out.
In our case, we have chosen not to run for Dolby certification as we chose to buy a 2k projector and do not have 35mm playback.

It should be noted that the room dimension chart is a guideline. I'm sure rooms that are not exactly "on the chart" could be certified if they sound good.

Steven

Steven,
Having a 2K projector and no 35mm playback is fine. I know many rooms here in Hollywood that don't have 35mm Film Playback and Dolby does Print Masters in the rooms. As a matter of fact I haven't done a 35mm Film Playback(even though I have a Film Projector) in at least 2 years yet have done probably 20 Print Masters with Dolby in that time!
Even on "the Studio Lots" hardly any Print Masters are done with Film any more!

[ggegan]

I haven't used a film projector more than once or twice in the last couple of years. There usually isn't any film printed until after the PM these days.

Most of these specs really relate to giving the Dolby engineers the ability to properly calibrate the speaker system for print mastering and being able to do basic quality control. Everything else is pretty generalized recommendations that are subject to different interpretations.

[Steven1145]

Originally Posted by dr.sound

Steven,
Having a 2K projector and no 35mm playback is fine. I know many rooms here in Hollywood that don't have 35mm Film Playback and Dolby does Print Masters in the rooms. As a matter of fact I haven't done a 35mm Film Playback(even though I have a Film Projector) in at least 2 years yet have done probably 20 Print Masters with Dolby in that time!
Even on "the Studio Lots" hardly any Print Masters are done with Film any more!

Very true, but every time I ask Dolby about the necessity of a 35mm projector they say that I need to have at least the capability to check a printmaster in our room, hence the need for the projector or at least a sound follower with an optical reader. I must say that most of the Dolby stages here have 35mm projection, but hardly any have a functionnal optical head to read an SR or SR-D print...

Maybe things will change soon enough.

[Fredo]

I have a Dolby document here which states that a 96 channel mixing console and 35mm projector are required to obtain Dolby Certification.
The document is a few years old though ...


Fredo

[jacobfarron]

I have a Dolby document here which states that a 96 channel mixing console and 35mm projector are required

What about Icons?

[dr.sound]

Originally Posted by jacobfarron

What about Icons?

Guys,
I wish everyone would state where they are from. There is a difference with requirements in Europe for example vs USA. My post replies are from what I have personally seen in the here in the US. You don't need an Icon or ......
Please contact Dolby for your questions. Don't speculate here!!

[Pedro_vde]

Originally Posted by Fredo

I have a Dolby document here which states that a 96 channel mixing console and 35mm projector are required to obtain Dolby Certification.

Our contacts with SSL states that the minimum console size is a 32 channel control surface to complete with Dolby specs, but I can't find no document stating that... (Tim are you there somewhere?)

Nothing about 35mm neither.

Kind regards from Belgium

Pedro

[danijel]

There is now (it appears for over a year) the 'Dolby Premier Studio Certification':

Dolby - Dolby Premier Studios – About the Program
White Mark Designs Europe’s First Film Dubbing Studio to Achieve Dolby Premier Studio Certification

Only 4 studios certified so far?

Are there any other similar certifications beside this and THX?

[minister]

Note: This program is not available in the US and Japan.

[danijel]

Originally Posted by minister

Note: This program is not available in the US and Japan.

Yes, I would like to know what is it between Dolby, US and Japan?

[Steven1145]

Just to keep you updated: what was that about only fools not changing their mind?...

So there you go, we went and got Dolby approval for Yellow Cab Studio A We realised that a few clients felt better when mixing in a room that has a big double D logo on the door.

To obtain the approval we needed to change/install a few things:
- Kinoton FP38EC 35/16mm studio projector (used)
- Kinoton reverse scan soundhead for Dolby SR and Dolby Digital (new)
- CB Electronics BS-1 LTC+9pin to biphase interface for the projector (used)
- Dolby CP650 SD (special studio model of the CP, with AES in and out) (new)
- JBL 8340A surrounds to replace the existing lower spec JBL 3310 (new)
- JBL 4645C subwoofer to rplace the existing lower spec JBL 3635 (new)

A lot of $$ and stress, but I believe it will pay back in the long run. We're waiting to know if we will get a new Dolby MME unit, but in the meantime Dolby will let us use a DMU for printmasters until the MME are in full production. Both the MME and DMU interface to the System5 via AES.

[Bill@AudioVision]

I was wondering if Dolby has any specific certification for 5.1 mixing for Television? They have tons of online documents to pour over, but I didn't seem to see anything similar to the film work certification.
Also, does anyone have knowledge of dts? Do they 'bless' rooms like Dolby?
Thanks all,
Bill

[MXDDXM]

Guys,

Just found this thread. Great to see all the interest. We don't publish the information on the internet, as the approval process is best accompanied by a contact person, plus as equipment changes and technology advances we make changes.

To contact me or James Seddon, our principle new studio approval chap, just phone us! +44 1793 842100 where we'd be happy to help as much as we can.

Sorry if anyone feels like I've snooped into this thread - just came across it while searching for a picture of a bit of Dolby gear.

Thanks,
Matt Dolby

[Jfriah]

Originally Posted by Fredo

I have a Dolby document here which states that a 96 channel mixing console and 35mm projector are required to obtain Dolby Certification.
The document is a few years old though ...


Fredo

Pssh! Tell that to my room which has an O2R just to handle some routing; we mix totally "in the box". Dolby couldn't possibly limit what mixing gear you are using as that doesn't affect (careful now!) reproduction/speaker chain.

"it ain't the size...it's what you do with it"

Console, I mean.

-Jeff

[Steven1145]

I suppose that in technical terms a PT system or other DAW is considered as the main console. Otherwise there would'nt be any Dolby approved ICON mixing stages.

[Smallbudgetguru]

Hi guys,

Does Dolby have different spec requirements for an approved mixing room in Canada(Quebec) ? Is it the same as the USA? If so has anyone achieved this certification and willing to share?

[cheflaco]

"it ain't the size...it's what you do with it"

Console, I mean.

-Jeff

[/QUOTE]

Another way to put it : "it ain't the arrow .... it's the Indian" ...or, the mixer