SOF

[william koon]

hi,

May I know movies shown in theatres are normally in SOF magnetic or sepmag ? If so, how many sound tracks are there ? thanks

[Brian Drysdale]

hi,

May I know movies shown in theatres are normally in SOF magnetic or sepmag ? If so, how many sound tracks are there ? thanks

 

The sound system in theatres uses an optical soundtrack rather than magnetic. It's these days it is Dolby Stereo that is the standard rather than the old mono. This system has 4 tracks: Left, Screen Centre, Right and the surround track. You can also get Dolby Digital which has 6 tracks (Left, Centre, Right, Left Surround, Right Surround) with a low frequency channel.

[Dominik Muench]

The sound system in theatres uses an optical soundtrack rather than magnetic. It's these days it is Dolby Stereo that is the standard rather than the old mono. This system has 4 tracks: Left, Screen Centre, Right and the surround track. You can also get Dolby Digital which has 6 tracks (Left, Centre, Right, Left Surround, Right Surround) with a low frequency channel.

 

 

for my understanding, the soundtrack comes on dvd/cd right ? and the optical strip on the film only syncs image and sound ?

[Brian Drysdale]

for my understanding, the soundtrack comes on dvd/cd right ? and the optical strip on the film only syncs image and sound ?

 

Yes, that's done with DTS and the Dolby Digital Cinema System, but most films still have older the Dolby analogue and digital optical sound tracks. Not forgetting plain optical sound.

[Leo Anthony Vale]

Yes, that's done with DTS and the Dolby Digital Cinema System, but most films still have older the Dolby analogue and digital optical sound tracks. Not forgetting plain optical sound.

 

---The dolby digital is not a seperate disc. It's printed on the film between the perfs.

 

The sony sdds digital system is also on the print, using tracks along the edges of the film.

 

The DTS sych track is usually printed between the picture and the analog track.

 

All three systems plus an analog stereo optical track can be printed onto the same print.

 

---LV

[Dominik Muench]

Yes, that's done with DTS and the Dolby Digital Cinema System, but most films still have older the Dolby analogue and digital optical sound tracks. Not forgetting plain optical sound.

 

 

ahh i see, thanks for that :)

[william koon]

ahh i see, thanks for that :)

 

Sorry for needing further explaination. When you mention DTC sync track printed on the film, does it mean magnetic digital track or something like DVD material pasted at the edge of the film ? I would be thankful if somebody can provide a diagram to illustrate. I am quite familiar with the optical sound track as mentioned. Do they run seperately like sepmag in theatre ?

[David Mullen ASC]

The sound is separate from the print, on a CD-ROM disc. An explanation from the DTS website:

 

DTS Digital Sound takes full advantage of digital storage technology advancements by putting data on the medium invented to store it: CD-ROM. Playing the correct sound for each frame of film projected, the DTS system reads timecode on the film and synchronizes playback from the CD-ROM discs. DTS' audio integrity is unaffected by film deterioration or degradation ? the print plays perfect sound whether on the first play date or the thousandth.

[william koon]

The sound is separate from the print, on a CD-ROM disc. An explanation from the DTS website:

 

DTS Digital Sound takes full advantage of digital storage technology advancements by putting data on the medium invented to store it: CD-ROM. Playing the correct sound for each frame of film projected, the DTS system reads timecode on the film and synchronizes playback from the CD-ROM discs. DTS' audio integrity is unaffected by film deterioration or degradation — the print plays perfect sound whether on the first play date or the thousandth.

 

TQ David. Anyway What DTS stands for ?

[David Mullen ASC]

There's a history here:

http://www.dts.com/company/history/brief_h...gy_overview.pdf

 

DTS = Digital Theater Systems

[Delorme Jean-Marie]

the history of sound formats in the projector is a s rich as the history of film formats, aspect ratio.

the only worldwide system matching all the projectors all over the planet is 35mm print with mono sound strip.

in the 80's sound and distributors have put together new ideas to push the industry.

and for each new sound format as a theater owner you had to buy the new sound optical or digital reader(some are more expensive than the projector itself!).

today the cannes film festival projector can run every existing sound system and it looks like a christmas tree!!!

 

dolby isn't a sound system it's a man, british : Ray Dolby he is now a billionnaire after invented a way to reduce the noise of the mechanics recording sound and it's only that : a compression!!

 

so the existing sounds are : mono and stereo with or without dolby

then you have brands : dts (recorded on cd, many languages possible) the cd sync to the film with a magnetic signal. the film still have it's mono or strereo strip added.

you have thx another brand wich have nothing to see with the copy but more with the equipment, amps etc...

it's a lucca's brand. Run a thx film in a non thx theater and it will a normal sound. and if you play a non thx film in a thx theater you'll have a very good sound

you have dolby digital a technology that record sound as digital images on the side strip (more info on a smaller area) vs the old stereo optical

you have sonics for imax theaters equal to dts technology.

notice that i don't talk about "incredible surround" wich is only a stereo effects with additional satelites speackers.

i hope it was clear

my 3 cents

[Delorme Jean-Marie]

another history of DTS

 

i don't know if it's true but it makes me laugth ;)

 

a French ingeneer invented the concept of DTS and proposed it to french industrials and invectors who never believed to it's concept to succed.

the ingeneer send it's beta version to the states to find an investor but the prototype had been stuck thru custom for months.

At this time a "Spielberg company" launch a great revolutionary concept the DTS !

I'm sure they had the same idea at the same moment

and our poor ingeneer came back doing it' "penguin march"

anyway dts works good and it's comparable to dolby digital (quality wise) it's a digital technology dts is on a cd and can carry much more information than dolby digital.

for exemple with dts you can have one print in american and a cd with x versions as with dolby digital you have one print per language

[Brian Drysdale]

---The dolby digital is not a seperate disc. It's printed on the film between the perfs.

 

The sony sdds digital system is also on the print, using tracks along the edges of the film.

 

The DTS sych track is usually printed between the picture and the analog track.

 

All three systems plus an analog stereo optical track can be printed onto the same print.

 

---LV

 

Checking the details again, the Dolby Digital Cinema System is for digital projection, but allows the programming of shows with both digital & Film content.

 

http://www.dolby.com/assets/pdf/tech_libra...410_DCinema.pdf

[Charles Haine]

Just to add a little clarity, THX is a set of standards, so that playback volume and projector brightness are standardized throughout the industry as opposed to individually set by the theatre owner or individual projectionist.

 

THX certification means that the theatre has been checked out and is set-up to project and play back sound to meet certain standards for the quality of the experience.

 

chuck

[Delorme Jean-Marie]

Just to add a little clarity, THX is a set of standards, so that playback volume and projector brightness are standardized throughout the industry as opposed to individually set by the theatre owner or individual projectionist.

 

THX certification means that the theatre has been checked out and is set-up to project and play back sound to meet certain standards for the quality of the experience.

 

chuck

sure but it's a brand, means that by this time, if you wanted to show the print of"star wars" in thx you had to do a huge invesment on thx products (wire, speaker....) provided and istaled by the company THX to be able to screen this particular THX film to the audiance.

to be more clear, for exemple in france we have the CST, it's a technical organization who chek the level of the instalation of a movie theatre prior to opening and we have also some thx theatre which is redondant.

and again thx is no more than technicaly top of the basket hardware with a sticker on it THX, nothing more on the print it's pure marketing!

what make me laugth is a THX dvd, with "incredible suround" ;) on a regular tv set :(

[John Pytlak RIP]

History of sound formats:

 

http://history.acusd.edu/gen/recording/motionpicture1.html

 

http://history.acusd.edu/gen/recording/motionpicture.html

 

http://history.acusd.edu/gen/recording/motionpicture3.html

 

http://www.mtsu.edu/~smpte/links.html

 

Today, most major 35mm releases have up to four sound formats on each print:

 

Analog (often Dolby SR encoded)

Dolby Digital

Sony SDDS

DTS (proprietary time code to sync separate digital audio files)

[Phil Rhodes]

Hi,

 

 

 

To be completely correct, there are only two channels on a standard dolby stereo track. The third and fourth are extracted by processing for information encoded with a phase matrix when the soundtrack is created. It's very clever as the separation is quite good. The oscillation of sound is represented as a pair of clear lines which vary in width on a black field.

 

This discussion would be incomplete without mentioning how variable area and variable density soundtracks work. Normal, modern, stereo sound is a "variable area" soundtrack and is less prone to clicks and pops caused by dirt than the first "variable density" systems which worked by printing a shade of grey, and which was also mono. The advantage here is that the variable area track creates a varying area of clear film, which can be read by a variable-area sound reader and reproduced as mono sound. Additionally, processing Dolby (or whatever Dolby-alike surround matrixing) information is optional and the soundtrack will sound fine when reproduced in simple stereo.

 

This backward-compatibility has been broken recently with the increased use of cyan-dye soundtracks, which work exactly as you'd expect and need a red LED lightsource to be correctly read. The purpose is to avoid the high-avidity developer used to develop the soundtrack area of the print to a high contrast black-or-white result with high D-max, which presents environmental problems.

 

We are now out of room:

 

 

Phil

[John Pytlak RIP]

More about cyan dye tracks:

 

http://www.dyetracks.org

 

In addition to eliminating the need for the caustic and viscous soundtrack developer, cyan dye tracks also greatly reduce fresh water use during processing, as much water was needed to wash off the developer without having it splash back onto the film causing silver stains in the image area. The modern reverse scan red LED readers offer significant quality and reliability advantages over the tungsten lamp readers they replace, including better frequency response.

[Phil Rhodes]

Hi,

 

Retrofitting LED exciter lamps onto old projectors really shows up the hum in the power supply, though!

 

Phil

[John Pytlak RIP]

Hi,

 

Retrofitting LED exciter lamps onto old projectors really shows up the hum in the power supply, though!

 

Phil

 

The LED reverse scan retrofits normally include a new, well filtered DC power supply.

 

Some of the lower price retrofits try to simply fit an LED module into the existing tungsten lamp socket, and they need extra amplification to get sufficient "Dolby Level". So hum and noise is sometimes an issue with them.