Movie Sound FAQ
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From: cal@gsbux1.uchicago.edu (Cal Lott)
Subject: Movie Sound FAQ 1.1.0
Message-ID: <1994Mar9.183157.2679@midway.uchicago.edu>
Sender: news@uchinews.uchicago.edu (News System)
Followups-To: rec.arts.movies
Organization: University of Chicago -- Academic Information Technologies
Date: Wed, 9 Mar 1994 18:31:57 GMT
Lines: 409
Xref: cyberspace.com rec.arts.movies:32104 rec.video.releases:3669 rec.audio:14182
Well, here it is -- the latest, greatest version of the Movie
Sound FAQ that I have been laboring away at. Boy, has it really
exploded in size! Some parts are still a little more than a rough
outline, so please don't be alarmed by speling, grammer, or abject
lack of style. (I would very much like factual corrections, however.)
I plan on filling in the sketchy sections once I have most of the
factual corrections under my belt.
Many, many thanks to all the great people that replied with
corrections, encouragement, and constructive comments and criticism.
This FAQ would not be possible without you!
Your comments, corrections, suggestions, and contributions
are quite welcome. Please reply here, or email me at "cal@gsbux1.
uchicago.edu". In order to keep the replies in one place, I have set
the Followup: line to rec.arts.movies, as this makes it feasible for
me to keep track of the corrective replies.
Please note that this is only intended to cover theatrical
sound systems, and only peripherally deals with the video/home theater
crossover topics like THX, Dolby Surround, and others.
Thanks, and I hope you enjoy it!
-----------------------------
Movie Sound Systems FAQ 1.1.0
-----------------------------
[Please note that these sections, except for the jargon glossary, will
be converted into normal prose at some time in the future.]
-------------------------------------
1) How movie soundtracks are produced
-------------------------------------
- Soundtracks are literally cobbled together one sound at a
time with foley tracks and other sound effects. Dialogue is then
dubbed in, and music added. This stuff all goes into various "stems",
from which the different masters are made.
- Each release format (Dolby Stereo, Dolby Stereo SR, 70mm,
and digital) has different limitations, and a master is optimized and
made for each format that the film will be released in.
- Modern masters are usually digital. (L1/L2 tape?)
- Optical 35mm soundtracks have compressed dynamic range, and
are stereo-only. (They can be Dolby-encoded stereo, of course.)
- 70mm mag stripe is basically a copy of the six-track master.
Dynamic range is extremely good.
- The various digital delivery systems are also copies of the
six-track master, but with lossy encoding and little to no compression
of dynamic range.
- [Some people have taken issue with my description of the
various digital surround systems as "lossy" systems, correctly pointing
out that the fidelity of these systems exceeds that of all others with
the possible exception of 70mm mag stripe. I do not call them "lossy"
systems because I think that their fidelity is low, but rather because
the digital soundtrack eventually placed on the print does not contain
all of the information present in the original six-track master. As for
the fidelity of each of these digital systems, each system can and will
stand on its own merits.]
---------------------------------------------------------
2) Matrix versus discrete surround sound: A short history
---------------------------------------------------------
First, here is an interesting reply from Peter Reiher on the
very early history of movies with sound:
----- Begin included text -----
Date: Tue, 25 Jan 94 08:05:54 -0800
From: Peter Reiher <reiher@ficus.cs.ucla.edu>
In message <9401250010.AA14309@gsbux1.uchicago.edu> Cal writes:
>
> Thanks for the reply. I was specifically hoping that you would
>compose a response, especially to the historical questions.
Here's a little more detailed information I looked up last night.
In the narrowest sense of the term, the first talking movie was
probably a test film W. K. Laurie Dickson showed to Thomas Edison as a
demonstration of the Kinetophonograph in 1889. Edison had assigned
Dickson to work on this at the same time Edison started development of
the Kinetograph. Amazingly, I believe that this bit of sound film
still exists. It's basically an Edison employee saying hello to
Edison from the screen, and saying a few other fairly trite things.
This system was a sound-on-disk system - essentially a Gramaphone
hooked up to a Kinetograph, with presumably some synchronization system.
The Kinetophonograph was deployed in some peep show parlors. Later,
another system using sound-on-disk was deployed into a few theaters.
A fire in Edison's labs in 1914 forever ended their experiments with
sound films, which were never commercially successful.
In 1904, a former Edison employee named Lauste developed a sound-on-
film system. It was not practical for use in theaters due to problems
with amplification. Amplification was actually the problem that kept
sound out of theaters for many years, rather than lack of technology
to match some form of sound with images.
Lee De Forest developed the solution in 1923, with the Phonofilm
system, a sound-on-film system. There were a number of experiments
with this system in the mid-20's, and eventually it was incorporated
into the Fox Movietone system. I believe D. W. Griffith used this
system to film a sound introduction to one of his films, "Dream Street".
In the introduction, Griffith himself stuffily addressed the audience
about the importance of the film in rather pretentious terms. The sound
of this exists, but not, I think, in its original format.
The first major commercial film with synchronized sound was "Don Juan",
in 1926. It used the Vitaphone, a sound-on-disk system. "The Jazz
Singer" was produced (by Warner Brothers, who'd also done "Don Juan")
in the same system in 1927. "Don Juan" had simply had a synchronized
score and some sound effects. "The Jazz Singer" had several musical
numbers and a handful of lines ad-libbed by Al Jolson. (For those who
tend to forget that movies are almost universally written, these ad-
libbed lines are among the few lines of significant dialog ever in the
history of fictional film that can be properly attributed to the actor
speaking it - with the exception of performers who wrote their own
scripts, like Woody Allen and Mae West.) By 1930, sound-on-disk had
been entirely replaced by various sound-on-film systems. Sound-on-disk
was totally abandoned until very recently - I believe one of the
current competing digital systems is sound-on-disk. It has the
advantage of being cheaper and requiring less equipment. It has the
disadvantage that you have to ship disks around, as well as film reels,
and presumably there's room for operator error in matching the wrong
disk to a reel.
Sound-on-film systems used one of two competing technologies. One was
variable-area soundtrack, and the other variable-density. Both used
a portion of the film not projected, out towards the sprocket holes.
Variable-area soundtracks fill a varying area of this part of the film
stock with solid black, encoding both pitch and volume information.
Variable-density instead fills the entire area with varying shades of
grey to encode the information. Both existed in the 30's, but I
believe variable-area eventually prevailed. There were a variety of
sub-schemes for variable-area encoding - fill from one side, fill from
both sides, fill from the center in one or both directions, etc. They
actually did have advantages, but I don't understand them well enough
to explain them.
Peter Reiher
----- End included text -----
- first talkies in mono.
- then came stereo. (Date? First stereo film?)
- Sensurround (???) (Can somebody clue me in on this one?)
- matrix refers to a way of deriving surround information
from only two channels of information. Dolby is the only matrix
surround encoding game in town nowadays and basically came in around
the time of STAR WARS. ('77) For more info on surround sound, go read
Bob Niland's excellent LD FAQ. (#3 -- I'll put in how to obtain it.)
- Around the time of RETURN OF THE JEDI (82-83), Lucasfilm
contracted an audio engineer named Tomlinson Holman to supervise
the design of a mixdown theater/studio at Skywalker Ranch to do the
sound production for JEDI. This was the genesis for the THX program,
which now includes the Theater Alignment Program. TAP periodically
inspects theaters to ensure that they are up to high standards of
audio and visual reproduction. Inspection is every six to twelve
months, and theaters that are up to spec get to use a THX-supplied
crossover and run the now-famous "Deep Note" trailer with the "THX:
The Audience Is Listening" logo. (For more information, please see the
entries below for TAP and THX.)
- The 90's have seen the rapid entry of the lossy-encoded
discrete-channel digital delivery systems, which seem to be the wave
of the future. For the first time, 35mm sound can equal (and some say
surpass) 70mm mag stripe sound.
----------------------------------------------
3) Jargon (A Concise Dictionary of Film Sound)
----------------------------------------------
70mm -- For many years, 70mm offered the best sound quality along with
the best picture quality. This higher quality was due to the
fact that the 70mm film stock is large enough to accommodate
six magnetic tracks, which made it the first discrete surround
sound delivery system. 70mm film is more expensive to produce
and exhibit than 35mm, so it was never widespread due to
economic reasons. The six channels included five (!) behind
the screen (LE/L/C/R/RE) and a mono surround. Modern 70mm
soundtracks use a more standard channel distribution, however:
(L/C/R/LS/RS/Boom). The current 70mm format uses the channels
originally reserved for LE & RE (Left Extra and Right Extra),
and mono surround to reproduce LS, RS, and Sub, respectively.
"A" playback chain -- One of two parts of a theater sound system. Its
counterpart is the "B" chain. (see entry) The A-chain refers
to the system that reads the sound information off of the
recording medium (usually the film itself, although DTS uses a
separate CD-ROM) and outputs a line-level signal of some sort.
AC-3 -- Dolby Lab's lossy digital encoding scheme. It compresses five
full range channels and one subwoofer channel with limited
frequency response into 64 to 640 kbits/sec of digital
information. AC-3 has been selected as the official surround
sound system for HDTV, and is starting to show up in some NTSC
laserdisc prototype systems. (Pioneer demoed such a system at
the Jan '94 Consumer Electronics Show.) Dolby Stereo Digital
and the forthcoming Dolby Surround Digital use AC-3.
"B" playback chain -- One of two parts of a theater sound system. Its
counterpart is the "A" chain. (see entry) The B-chain refers
to the amplifier, crossovers, and speakers that accept a line-
level signal from the A-chain and then amplify and route it to
produce audible sound.
Boom Channel -- A nickname for the subwoofer channel. So-called
because it is often used to accentuate explosions, gun blasts,
and other special effects.
CDS (Cinema Digital Sound) -- One of the very early digital delivery
systems, put out by Kodak. TERMINATOR 2: JUDGEMENT DAY was the
major film released in this format. It never saw wide
distribution due to a variety of factors, especially due to
the fact that there were no backups to the digital sound
tracks. (If they failed, the theater went completely silent!)
This system is now defunct.
Dolby -- The last name of Ray Dolby, audio engineer and founder of
Dolby Laboratories. Dolby Labs has made a name for itself in
the audio industry with noise reduction and surround sound
technologies. If a movie is said to be "in Dolby", it usually
means that its stereo soundtrack has been Dolby-encoded for
matrixed surround sound.
Dolby Digital -- (see Dolby Stereo Digital)
Dolby SR -- Short for Dolby Spectral Recording. (see entry under Dolby
Stereo SR.
Dolby SR -- Dolby Spectral Recording is basically a way to get a
little more (3dB) of dynamic range out the standard optical
soundtrack. (Anybody with more info on how this is done,
please enlighten me.)
Dolby SR-D -- This designation is shorthand for a film that has the
best quality digital and analog soundtracks that Dolby can
offer. For a print to be a Dolby SR-D print, it must have
both a Dolby Stereo Digital digital soundtrack and a Dolby
Stereo SR analog soundtrack. (see respective entries)
Dolby Stereo -- This Dolby's term for the process of creating a Dolby
encoded stereo soundtrack and putting it on the optical
soundtracks of a 35mm film. It is more than just putting the
Dolby matrix encoding in the soundtrack -- the Dolby Stereo
process also employs noise reduction (Dolby A, Dolby SR) and
other film-specific processes intended to optimize the
soundtrack for presentation in a theater on film. Nearly all
modern film soundtracks (at least in America) use Dolby Stereo
or a similar process on their films. (see also Ultra Stereo)
Dolby Stereo Digital -- The Dolby Labs digital sound system. It uses
the AC-3 compression scheme, which stores the 5.1 channels in
a 320 kbit/sec digital information stream. This information is
stored in between the sprocket holes of the 35mm projection
print. The Dolby Digital trailer is a spectral steam engine,
and is widely considered to be the most impressive of the
four systems. Dolby recently cut the price of a Dolby Digital
theater system in order to be more price competitive with
their main competitor, DTS. (see entry)
Dolby Stereo SR -- Short for Dolby Stereo Spectral Recording. The SR
process is the latest, greatest way that Dolby has for
squeezing maximum fidelity out of 35mm optical stereo
soundtracks. It squeezes in extra dynamic range (~3dB) and
uses more advanced noise reduction than plain Dolby Stereo.
Dolby Surround -- This is Dolby's name for their home consumer
surround technology. Plain Dolby and Dolby Pro-Logic are ways
of decoding the matrixed surround sound found in the stereo
soundtracks of movies on VCR or laserdisc. (For more
information on Dolby Surround in the home video setting, see
Bob Niland's excellent FAQ on it -- #3 in the series of
laserdisc faqs.)
Dolby Surround Digital -- Dolby's name for their forthcoming digital
sound system for consumers. It parallels Dolby Stereo Digital
in that it is a 5.1 channel system (L/C/R/Ls/Rs/Boom), and
uses the AC-3 encoding algorithm. (see respective entries)
The HDTV alliance recently approved a 384kbps variant of Dolby
Surround Digital for use in their forthcoming standard.
DTS (Digital Theater Sound) -- One of the two main discrete digital
5.1 channel systems currently in use. It is unique in that the
encoded digital information is stored on a CD-ROM, and synced
to the 35mm print via imprinted timecodes. The optical analog
track is kept as a backup. The company behind DTS is <xxxxxx>,
the principal manufacturers of the optical soundtrack pickups
found on many 35mm projectors currently in use today. DTS got
a big rollout in the summer of '93 for the Spielberg mega-
blockbuster JURASSIC PARK, released by Universal. Universal
was reportedly so pleased with the response that they have
committed to producing all future releases in DTS. (DTS had
some quality control problems when they first released the
system into theaters that had only four-channel capability and
used old B chain equipment for playback. The DTS trailer was
encoded with analog as well as digital sound, and some non-DTS
theaters did not snip the trailer as they should have. Many
people thought that they were seeing full-bore DTS-6 (discrete
six-channel L/C/R/Boom/LS/RS) when in fact they were seeing
inferior four-channel DTS-S or even old Dolby Stereo optical
matrix surround! DTS quickly realized these problems, and will
upgrade all DTS installations to DTS-6, and encode their trailer
with only digital sound -- no analog.) The DTS trailer is a
bunch of motes that whirl around and coalesce into the DTS
logo. (Not nearly as cool as the Dolby Digital train, IMO.)
Sensurround -- A short-lived system (in the early fifties?) that
delivered thunderous low-frequency rumbles at selected points
during a film by playing low-frequency pink noise through lots
of woofers located about the theater. The three known
Sensurround releases were EARTHQUAKE, MIDWAY, and
ROLLERCOASTER.
SDDS (Sony Dynamic Digital Sound) -- (thanks to Alan Jay, alanj@
ibmpcug.co.uk) Another entry in the discrete digital format
horse race, along with DTS and Dolby Digital. (see entries)
This system uses ATRAC-style lossy encoding on a digital
soundtrack that can be encoded and played back with 8 (L/LC/
RC/R/Boom/LS/RS), 6 or 5.1 (L/C/R/Boom/RS/LS), or 4 (LF/RF/
LS/RS) channels, all discrete. The digital information is
stored between the sprocket holes on *both* sides of the 35mm
film print, and keeps the optical analog track as a backup.
TAP -- Short for the Lucasfilm THX Theater Alignment Program. This is
the division of Lucasfilm THX that provides various services
for for the film industry, including supervision of feature
film releases by Lucasfilm on behalf of the studio. These
services include (1) print and reel by reel review, (2)
technical assistance in the alignment and calibration of
theater A and B playback chains, and (3) evaluation of actual
theatrical presentations in theaters (print condition, sound,
theater services, etc.)
THX -- A Lucasfilm quality-control program that is dedicated to
maintaining a high standard of visual and audio quality in
theatrical presentations. (And now video and home theater as
well, but that's another story.) The THX Theater Alignment
Program conducts periodic inspections of theaters and certifies
them if they meet certain standards. (Also see TAP entry above.)
Certified theaters get to run the cool "Deep Note" trailer
before their feature presentation.
-------------------------------
Credits (In Alphabetical Order)
-------------------------------
Many, many thanks to all of these people and everybody else who has
contributed to this FAQ. My apologies if I have left you out!
Thanks to:
Ron Higgins <rhiggins@carroll1.cc.edu> for forwarding all those non-
Usenet replies to me in the early days of this FAQ, and for
prodding me to get the revisions done. 8-)
Alan Jay <alanj@ibmpcug.co.uk> for sharing his excellent article on
the Sony SDDS system.
Michael Lodman <mlodman@procy.gi.com> for technical info on AC-3.
Paul Matiwy <mstrmat@aol.com> of Lucasfilm THX for information on
THX, 70mm, soundtrack masters, and other miscellaneous stuff.
Peter Reiher <reiher@wells.cs.ucla.edu> for his excellent and
informative essay on the beginnings of sound in the movies.
Steve Thompson <dolbyman@aol.com> of Dolby Labs for setting me
straight on Dolby's terminology for their systems.
Mark Vita <vita@gloucester.dab.ge.com> for sharing his DTS info.
I highly recommend Widescreen Review to those people that have an
interest in movie sound and in high-quality video reproduction in
their own home. It's terribly hard to find on newsstands -- email me
if you would like subscription information.
---------------
Version History
---------------
1.0.0 1/94 Proto-FAQ. A sketchy, basic outline. First posted to
Usenet on 1/18/94 for additions and corrections.
1.0.1 1/94 Added a few new Dolby entries, and A-chain and B-chain
entries. Never posted to Usenet.
1.1.0 3/94 Various and sundry major revisions throughout. Release
date on 3/9/94.
----------------
Copyright Notice
----------------
This document is copyright 1994 by Cal Lott. Rights for unlimited non-
commercial use of this document, including retransmission over Usenet
and other computer networks is expressly permitted, provided that
this document is transmitted in its entirety, including this notice.
All other rights are expressly reserved.
--
----------------------------------------------------------------------
"From all us Slackers to all you Boomers ... HAHAHAHAHAHA! WE HAVE
SATELLITE MOUNTED RAIL-GUNS! HEH HEH. Who's laughing now?"-- S. Lang
----------------------------------------------------------------------
Newsgroups: rec.arts.movies,rec.video.releases,rec.audio
Path: cyberspace.com!news.sprintlink.net!uunet!panix!ddsw1!news.kei.com!eff!news.umbc.edu!europa.eng.gtefsd.com!howland.reston.ans.net!vixen.cso.uiuc.edu!uchinews!gsbux1!cal
From: cal@gsbux1.uchicago.edu (Cal Lott)
Subject: Movie Sound FAQ 1.1.0
Message-ID: <1994Mar9.183157.2679@midway.uchicago.edu>
Sender: news@uchinews.uchicago.edu (News System)
Followups-To: rec.arts.movies
Organization: University of Chicago -- Academic Information Technologies
Date: Wed, 9 Mar 1994 18:31:57 GMT
Lines: 409
Xref: cyberspace.com rec.arts.movies:32104 rec.video.releases:3669 rec.audio:14182
Well, here it is -- the latest, greatest version of the Movie
Sound FAQ that I have been laboring away at. Boy, has it really
exploded in size! Some parts are still a little more than a rough
outline, so please don't be alarmed by speling, grammer, or abject
lack of style. (I would very much like factual corrections, however.)
I plan on filling in the sketchy sections once I have most of the
factual corrections under my belt.
Many, many thanks to all the great people that replied with
corrections, encouragement, and constructive comments and criticism.
This FAQ would not be possible without you!
Your comments, corrections, suggestions, and contributions
are quite welcome. Please reply here, or email me at "cal@gsbux1.
uchicago.edu". In order to keep the replies in one place, I have set
the Followup: line to rec.arts.movies, as this makes it feasible for
me to keep track of the corrective replies.
Please note that this is only intended to cover theatrical
sound systems, and only peripherally deals with the video/home theater
crossover topics like THX, Dolby Surround, and others.
Thanks, and I hope you enjoy it!
-----------------------------
Movie Sound Systems FAQ 1.1.0
-----------------------------
[Please note that these sections, except for the jargon glossary, will
be converted into normal prose at some time in the future.]
-------------------------------------
1) How movie soundtracks are produced
-------------------------------------
- Soundtracks are literally cobbled together one sound at a
time with foley tracks and other sound effects. Dialogue is then
dubbed in, and music added. This stuff all goes into various "stems",
from which the different masters are made.
- Each release format (Dolby Stereo, Dolby Stereo SR, 70mm,
and digital) has different limitations, and a master is optimized and
made for each format that the film will be released in.
- Modern masters are usually digital. (L1/L2 tape?)
- Optical 35mm soundtracks have compressed dynamic range, and
are stereo-only. (They can be Dolby-encoded stereo, of course.)
- 70mm mag stripe is basically a copy of the six-track master.
Dynamic range is extremely good.
- The various digital delivery systems are also copies of the
six-track master, but with lossy encoding and little to no compression
of dynamic range.
- [Some people have taken issue with my description of the
various digital surround systems as "lossy" systems, correctly pointing
out that the fidelity of these systems exceeds that of all others with
the possible exception of 70mm mag stripe. I do not call them "lossy"
systems because I think that their fidelity is low, but rather because
the digital soundtrack eventually placed on the print does not contain
all of the information present in the original six-track master. As for
the fidelity of each of these digital systems, each system can and will
stand on its own merits.]
---------------------------------------------------------
2) Matrix versus discrete surround sound: A short history
---------------------------------------------------------
First, here is an interesting reply from Peter Reiher on the
very early history of movies with sound:
----- Begin included text -----
Date: Tue, 25 Jan 94 08:05:54 -0800
From: Peter Reiher <reiher@ficus.cs.ucla.edu>
In message <9401250010.AA14309@gsbux1.uchicago.edu> Cal writes:
>
> Thanks for the reply. I was specifically hoping that you would
>compose a response, especially to the historical questions.
Here's a little more detailed information I looked up last night.
In the narrowest sense of the term, the first talking movie was
probably a test film W. K. Laurie Dickson showed to Thomas Edison as a
demonstration of the Kinetophonograph in 1889. Edison had assigned
Dickson to work on this at the same time Edison started development of
the Kinetograph. Amazingly, I believe that this bit of sound film
still exists. It's basically an Edison employee saying hello to
Edison from the screen, and saying a few other fairly trite things.
This system was a sound-on-disk system - essentially a Gramaphone
hooked up to a Kinetograph, with presumably some synchronization system.
The Kinetophonograph was deployed in some peep show parlors. Later,
another system using sound-on-disk was deployed into a few theaters.
A fire in Edison's labs in 1914 forever ended their experiments with
sound films, which were never commercially successful.
In 1904, a former Edison employee named Lauste developed a sound-on-
film system. It was not practical for use in theaters due to problems
with amplification. Amplification was actually the problem that kept
sound out of theaters for many years, rather than lack of technology
to match some form of sound with images.
Lee De Forest developed the solution in 1923, with the Phonofilm
system, a sound-on-film system. There were a number of experiments
with this system in the mid-20's, and eventually it was incorporated
into the Fox Movietone system. I believe D. W. Griffith used this
system to film a sound introduction to one of his films, "Dream Street".
In the introduction, Griffith himself stuffily addressed the audience
about the importance of the film in rather pretentious terms. The sound
of this exists, but not, I think, in its original format.
The first major commercial film with synchronized sound was "Don Juan",
in 1926. It used the Vitaphone, a sound-on-disk system. "The Jazz
Singer" was produced (by Warner Brothers, who'd also done "Don Juan")
in the same system in 1927. "Don Juan" had simply had a synchronized
score and some sound effects. "The Jazz Singer" had several musical
numbers and a handful of lines ad-libbed by Al Jolson. (For those who
tend to forget that movies are almost universally written, these ad-
libbed lines are among the few lines of significant dialog ever in the
history of fictional film that can be properly attributed to the actor
speaking it - with the exception of performers who wrote their own
scripts, like Woody Allen and Mae West.) By 1930, sound-on-disk had
been entirely replaced by various sound-on-film systems. Sound-on-disk
was totally abandoned until very recently - I believe one of the
current competing digital systems is sound-on-disk. It has the
advantage of being cheaper and requiring less equipment. It has the
disadvantage that you have to ship disks around, as well as film reels,
and presumably there's room for operator error in matching the wrong
disk to a reel.
Sound-on-film systems used one of two competing technologies. One was
variable-area soundtrack, and the other variable-density. Both used
a portion of the film not projected, out towards the sprocket holes.
Variable-area soundtracks fill a varying area of this part of the film
stock with solid black, encoding both pitch and volume information.
Variable-density instead fills the entire area with varying shades of
grey to encode the information. Both existed in the 30's, but I
believe variable-area eventually prevailed. There were a variety of
sub-schemes for variable-area encoding - fill from one side, fill from
both sides, fill from the center in one or both directions, etc. They
actually did have advantages, but I don't understand them well enough
to explain them.
Peter Reiher
----- End included text -----
- first talkies in mono.
- then came stereo. (Date? First stereo film?)
- Sensurround (???) (Can somebody clue me in on this one?)
- matrix refers to a way of deriving surround information
from only two channels of information. Dolby is the only matrix
surround encoding game in town nowadays and basically came in around
the time of STAR WARS. ('77) For more info on surround sound, go read
Bob Niland's excellent LD FAQ. (#3 -- I'll put in how to obtain it.)
- Around the time of RETURN OF THE JEDI (82-83), Lucasfilm
contracted an audio engineer named Tomlinson Holman to supervise
the design of a mixdown theater/studio at Skywalker Ranch to do the
sound production for JEDI. This was the genesis for the THX program,
which now includes the Theater Alignment Program. TAP periodically
inspects theaters to ensure that they are up to high standards of
audio and visual reproduction. Inspection is every six to twelve
months, and theaters that are up to spec get to use a THX-supplied
crossover and run the now-famous "Deep Note" trailer with the "THX:
The Audience Is Listening" logo. (For more information, please see the
entries below for TAP and THX.)
- The 90's have seen the rapid entry of the lossy-encoded
discrete-channel digital delivery systems, which seem to be the wave
of the future. For the first time, 35mm sound can equal (and some say
surpass) 70mm mag stripe sound.
----------------------------------------------
3) Jargon (A Concise Dictionary of Film Sound)
----------------------------------------------
70mm -- For many years, 70mm offered the best sound quality along with
the best picture quality. This higher quality was due to the
fact that the 70mm film stock is large enough to accommodate
six magnetic tracks, which made it the first discrete surround
sound delivery system. 70mm film is more expensive to produce
and exhibit than 35mm, so it was never widespread due to
economic reasons. The six channels included five (!) behind
the screen (LE/L/C/R/RE) and a mono surround. Modern 70mm
soundtracks use a more standard channel distribution, however:
(L/C/R/LS/RS/Boom). The current 70mm format uses the channels
originally reserved for LE & RE (Left Extra and Right Extra),
and mono surround to reproduce LS, RS, and Sub, respectively.
"A" playback chain -- One of two parts of a theater sound system. Its
counterpart is the "B" chain. (see entry) The A-chain refers
to the system that reads the sound information off of the
recording medium (usually the film itself, although DTS uses a
separate CD-ROM) and outputs a line-level signal of some sort.
AC-3 -- Dolby Lab's lossy digital encoding scheme. It compresses five
full range channels and one subwoofer channel with limited
frequency response into 64 to 640 kbits/sec of digital
information. AC-3 has been selected as the official surround
sound system for HDTV, and is starting to show up in some NTSC
laserdisc prototype systems. (Pioneer demoed such a system at
the Jan '94 Consumer Electronics Show.) Dolby Stereo Digital
and the forthcoming Dolby Surround Digital use AC-3.
"B" playback chain -- One of two parts of a theater sound system. Its
counterpart is the "A" chain. (see entry) The B-chain refers
to the amplifier, crossovers, and speakers that accept a line-
level signal from the A-chain and then amplify and route it to
produce audible sound.
Boom Channel -- A nickname for the subwoofer channel. So-called
because it is often used to accentuate explosions, gun blasts,
and other special effects.
CDS (Cinema Digital Sound) -- One of the very early digital delivery
systems, put out by Kodak. TERMINATOR 2: JUDGEMENT DAY was the
major film released in this format. It never saw wide
distribution due to a variety of factors, especially due to
the fact that there were no backups to the digital sound
tracks. (If they failed, the theater went completely silent!)
This system is now defunct.
Dolby -- The last name of Ray Dolby, audio engineer and founder of
Dolby Laboratories. Dolby Labs has made a name for itself in
the audio industry with noise reduction and surround sound
technologies. If a movie is said to be "in Dolby", it usually
means that its stereo soundtrack has been Dolby-encoded for
matrixed surround sound.
Dolby Digital -- (see Dolby Stereo Digital)
Dolby SR -- Short for Dolby Spectral Recording. (see entry under Dolby
Stereo SR.
Dolby SR -- Dolby Spectral Recording is basically a way to get a
little more (3dB) of dynamic range out the standard optical
soundtrack. (Anybody with more info on how this is done,
please enlighten me.)
Dolby SR-D -- This designation is shorthand for a film that has the
best quality digital and analog soundtracks that Dolby can
offer. For a print to be a Dolby SR-D print, it must have
both a Dolby Stereo Digital digital soundtrack and a Dolby
Stereo SR analog soundtrack. (see respective entries)
Dolby Stereo -- This Dolby's term for the process of creating a Dolby
encoded stereo soundtrack and putting it on the optical
soundtracks of a 35mm film. It is more than just putting the
Dolby matrix encoding in the soundtrack -- the Dolby Stereo
process also employs noise reduction (Dolby A, Dolby SR) and
other film-specific processes intended to optimize the
soundtrack for presentation in a theater on film. Nearly all
modern film soundtracks (at least in America) use Dolby Stereo
or a similar process on their films. (see also Ultra Stereo)
Dolby Stereo Digital -- The Dolby Labs digital sound system. It uses
the AC-3 compression scheme, which stores the 5.1 channels in
a 320 kbit/sec digital information stream. This information is
stored in between the sprocket holes of the 35mm projection
print. The Dolby Digital trailer is a spectral steam engine,
and is widely considered to be the most impressive of the
four systems. Dolby recently cut the price of a Dolby Digital
theater system in order to be more price competitive with
their main competitor, DTS. (see entry)
Dolby Stereo SR -- Short for Dolby Stereo Spectral Recording. The SR
process is the latest, greatest way that Dolby has for
squeezing maximum fidelity out of 35mm optical stereo
soundtracks. It squeezes in extra dynamic range (~3dB) and
uses more advanced noise reduction than plain Dolby Stereo.
Dolby Surround -- This is Dolby's name for their home consumer
surround technology. Plain Dolby and Dolby Pro-Logic are ways
of decoding the matrixed surround sound found in the stereo
soundtracks of movies on VCR or laserdisc. (For more
information on Dolby Surround in the home video setting, see
Bob Niland's excellent FAQ on it -- #3 in the series of
laserdisc faqs.)
Dolby Surround Digital -- Dolby's name for their forthcoming digital
sound system for consumers. It parallels Dolby Stereo Digital
in that it is a 5.1 channel system (L/C/R/Ls/Rs/Boom), and
uses the AC-3 encoding algorithm. (see respective entries)
The HDTV alliance recently approved a 384kbps variant of Dolby
Surround Digital for use in their forthcoming standard.
DTS (Digital Theater Sound) -- One of the two main discrete digital
5.1 channel systems currently in use. It is unique in that the
encoded digital information is stored on a CD-ROM, and synced
to the 35mm print via imprinted timecodes. The optical analog
track is kept as a backup. The company behind DTS is <xxxxxx>,
the principal manufacturers of the optical soundtrack pickups
found on many 35mm projectors currently in use today. DTS got
a big rollout in the summer of '93 for the Spielberg mega-
blockbuster JURASSIC PARK, released by Universal. Universal
was reportedly so pleased with the response that they have
committed to producing all future releases in DTS. (DTS had
some quality control problems when they first released the
system into theaters that had only four-channel capability and
used old B chain equipment for playback. The DTS trailer was
encoded with analog as well as digital sound, and some non-DTS
theaters did not snip the trailer as they should have. Many
people thought that they were seeing full-bore DTS-6 (discrete
six-channel L/C/R/Boom/LS/RS) when in fact they were seeing
inferior four-channel DTS-S or even old Dolby Stereo optical
matrix surround! DTS quickly realized these problems, and will
upgrade all DTS installations to DTS-6, and encode their trailer
with only digital sound -- no analog.) The DTS trailer is a
bunch of motes that whirl around and coalesce into the DTS
logo. (Not nearly as cool as the Dolby Digital train, IMO.)
Sensurround -- A short-lived system (in the early fifties?) that
delivered thunderous low-frequency rumbles at selected points
during a film by playing low-frequency pink noise through lots
of woofers located about the theater. The three known
Sensurround releases were EARTHQUAKE, MIDWAY, and
ROLLERCOASTER.
SDDS (Sony Dynamic Digital Sound) -- (thanks to Alan Jay, alanj@
ibmpcug.co.uk) Another entry in the discrete digital format
horse race, along with DTS and Dolby Digital. (see entries)
This system uses ATRAC-style lossy encoding on a digital
soundtrack that can be encoded and played back with 8 (L/LC/
RC/R/Boom/LS/RS), 6 or 5.1 (L/C/R/Boom/RS/LS), or 4 (LF/RF/
LS/RS) channels, all discrete. The digital information is
stored between the sprocket holes on *both* sides of the 35mm
film print, and keeps the optical analog track as a backup.
TAP -- Short for the Lucasfilm THX Theater Alignment Program. This is
the division of Lucasfilm THX that provides various services
for for the film industry, including supervision of feature
film releases by Lucasfilm on behalf of the studio. These
services include (1) print and reel by reel review, (2)
technical assistance in the alignment and calibration of
theater A and B playback chains, and (3) evaluation of actual
theatrical presentations in theaters (print condition, sound,
theater services, etc.)
THX -- A Lucasfilm quality-control program that is dedicated to
maintaining a high standard of visual and audio quality in
theatrical presentations. (And now video and home theater as
well, but that's another story.) The THX Theater Alignment
Program conducts periodic inspections of theaters and certifies
them if they meet certain standards. (Also see TAP entry above.)
Certified theaters get to run the cool "Deep Note" trailer
before their feature presentation.
-------------------------------
Credits (In Alphabetical Order)
-------------------------------
Many, many thanks to all of these people and everybody else who has
contributed to this FAQ. My apologies if I have left you out!
Thanks to:
Ron Higgins <rhiggins@carroll1.cc.edu> for forwarding all those non-
Usenet replies to me in the early days of this FAQ, and for
prodding me to get the revisions done. 8-)
Alan Jay <alanj@ibmpcug.co.uk> for sharing his excellent article on
the Sony SDDS system.
Michael Lodman <mlodman@procy.gi.com> for technical info on AC-3.
Paul Matiwy <mstrmat@aol.com> of Lucasfilm THX for information on
THX, 70mm, soundtrack masters, and other miscellaneous stuff.
Peter Reiher <reiher@wells.cs.ucla.edu> for his excellent and
informative essay on the beginnings of sound in the movies.
Steve Thompson <dolbyman@aol.com> of Dolby Labs for setting me
straight on Dolby's terminology for their systems.
Mark Vita <vita@gloucester.dab.ge.com> for sharing his DTS info.
I highly recommend Widescreen Review to those people that have an
interest in movie sound and in high-quality video reproduction in
their own home. It's terribly hard to find on newsstands -- email me
if you would like subscription information.
---------------
Version History
---------------
1.0.0 1/94 Proto-FAQ. A sketchy, basic outline. First posted to
Usenet on 1/18/94 for additions and corrections.
1.0.1 1/94 Added a few new Dolby entries, and A-chain and B-chain
entries. Never posted to Usenet.
1.1.0 3/94 Various and sundry major revisions throughout. Release
date on 3/9/94.
----------------
Copyright Notice
----------------
This document is copyright 1994 by Cal Lott. Rights for unlimited non-
commercial use of this document, including retransmission over Usenet
and other computer networks is expressly permitted, provided that
this document is transmitted in its entirety, including this notice.
All other rights are expressly reserved.
--
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"From all us Slackers to all you Boomers ... HAHAHAHAHAHA! WE HAVE
SATELLITE MOUNTED RAIL-GUNS! HEH HEH. Who's laughing now?"-- S. Lang
----------------------------------------------------------------------
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