U.S. patent number RE44,261 [Application Number 13/341,861] was granted by the patent office on 2013-06-04 for volume control for audio signals.
This patent grant is currently assigned to Dolby Laboratories Licensing Corporation. The grantee listed for this patent is Stephen M. Jacobs. Invention is credited to Stephen M. Jacobs.
United States Patent |
RE44,261 |
Jacobs |
June 4, 2013 |
Volume control for audio signals
Abstract
A motion picture soundtrack reproduction system has a center
front soundtrack channel and a plurality of other soundtrack
channels. A volume control adjusts the gain of all the channels.
The volume control has a range of settings from a minimum to a
maximum, the gain of the center front channel having substantially
a first relationship to the volume control settings and the gain of
the other channels having substantially a second relationship to
the volume control settings, the relationships being such that for
a range of volume control settings less than a first setting the
gain of the center front channel remains substantially constant
while the gain of the other channels decreases as the setting
decreases or decreases more gradually than the gain of the other
channels as the setting decreases.
Inventors: |
Jacobs; Stephen M. (Cupertino,
CA) |
Applicant: |
Name |
City |
State |
Country |
Type |
Jacobs; Stephen M. |
Cupertino |
CA |
US |
|
|
Assignee: |
Dolby Laboratories Licensing
Corporation (San Francisco, CA)
|
Family
ID: |
33299218 |
Appl.
No.: |
13/341,861 |
Filed: |
December 30, 2011 |
Related U.S. Patent Documents
|
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
Issue Date |
|
|
12493111 |
Jan 24, 2012 |
Re. 43132 |
|
|
Reissue of: |
10423829 |
Apr 24, 2003 |
7251337 |
Jul 31, 2007 |
|
|
Current U.S.
Class: |
381/107; 381/27;
381/104; 381/22; 381/19 |
Current CPC
Class: |
H04S
7/00 (20130101); H03G 3/00 (20130101); H04S
2400/13 (20130101) |
Current International
Class: |
H03G
3/00 (20060101) |
Field of
Search: |
;381/19-23,27,102-109 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
|
|
|
|
|
|
|
198 18 217 |
|
Oct 1998 |
|
DE |
|
19818217 |
|
Oct 1998 |
|
DE |
|
1253805 |
|
Oct 2002 |
|
EP |
|
1254513 |
|
Nov 2002 |
|
EP |
|
1328141 |
|
Aug 1973 |
|
GB |
|
2031638 |
|
Apr 1980 |
|
GB |
|
59-177534 |
|
Oct 1984 |
|
JP |
|
59-186500 |
|
Oct 1984 |
|
JP |
|
2907847 |
|
Jul 1990 |
|
JP |
|
2002-191099 |
|
Jul 2002 |
|
JP |
|
2002-354600 |
|
Dec 2002 |
|
JP |
|
WO 99/26455 |
|
May 1990 |
|
WO |
|
WO 0139370 |
|
May 2001 |
|
WO |
|
WO 0139370 |
|
May 2001 |
|
WO |
|
Other References
JP Office Action for foreign patent application No. 2006-510077,
dated Aug. 27, 2009 (4 pages of English translation and original
OA). cited by applicant .
Current claims for JP foreign patent application No. 2006-510077 (2
pages). cited by applicant .
Applicant's admitted prior art, p. 1, line 12-p. 4, line 11, Figure
1. cited by applicant .
Ioan Allen, "Are Movies Too Loud?," SMPTE Film Conference, Mar. 22,
1997. cited by applicant .
Dolby Laboratories, Inc., "Dolby Model 737 Soundtrack Loudness
Meter" brochure, Copyright 1998. cited by applicant .
Dolby Laboratories, Inc., "Dolby Model 737 Soundtrack Loudness
Meter-Leq(m) Users' Manual Issue 3, Part No. 91533," Copyright
2000. cited by applicant .
Press Release--Dolby Laboratories, Inc., "Dolby Announces New
Effort to Banish TV Volume Problems at AES-2002," 112th AES
Convention in Munich, May 10-13, 2002. cited by applicant .
Dolby Laboratories, Inc., "LM 100 Broadcast Loudness Meter
Preliminary Information" brochure, Copyright 2002. cited by
applicant .
Dolby Laboratories, Inc., "LM 100 Broadcast Loudness Meter,"
Copyright 2002. cited by applicant .
Dolby Laboratories, Inc., "Preliminary Specification LM100
Broadcast Loudness Meter," Copyright 2002. cited by applicant .
Dolby Laboratories, Inc., "Dolby Model 737 Soundtrack Loudness
Meter," Copyright 2002. cited by applicant .
Dolby Laboratories, Inc., "Dolby Model DP564 Multichannel Audio
Decoder Users' Manual Issue I, Part No. 91830," Copyright 2002.
cited by applicant .
Bauer, Benjamin B., et al., "The Measurement of Loudness Level,"
Journal of the Acoustical Society of America, Aug. 1971, pp.
405-414. cited by applicant.
|
Primary Examiner: Paul; Disler
Attorney, Agent or Firm: Hickman Palermo Truong Becker
Bingham Wong LLP Wong; Kirk D.
Parent Case Text
.Iadd.CROSS-REFERENCE TO RELATED APPLICATIONS; BENEFIT
CLAIM.Iaddend.
.Iadd.More than one Reissue Application has been filed for the
reissue of U.S. Pat. No. 7,251,337, issued Jul. 31, 2007. The
reissue applications are application Ser. No. 12/493,111 filed Jun.
26, 2009, Ser. No. 13/341,871 filed Dec. 30, 2011, Ser. No.
13/341,870 filed Dec. 30, 2011, Ser. No. 13/341,873 filed Dec. 30,
2011, and Ser. No. 13/341,861 filed Dec. 30, 2011 (the present
application). The present application claims the benefit as a
Reissue Continuation Application of application Ser. No.
12/493,111, filed Jun. 26, 2009 (now RE43,132, issued on Jan. 24,
2012), which is a Reissue Application of U.S. Pat. No. 7,251,337,
issued Jul. 31, 2007 (application Ser. No. 10/423,829, filed Apr.
24, 2003), the entire contents of all of the foregoing are hereby
incorporated by reference as if fully set forth herein, under 35
U.S.C. .sctn.120. Applicants hereby rescind any disclaimer of claim
scope in the parent application(s) or the prosecution history
thereof and advise the USPTO that the claims in this application
may be broader than any claim in the parent
application(s)..Iaddend.
Claims
The invention claimed is:
.[.1. A motion picture soundtrack reproduction system, the system
having a center front soundtrack channel and a plurality of other
soundtrack channels, comprising a controller having a volume
control for adjusting the gain of all the channels, the volume
control having a range of settings from a minimum to a maximum, the
controller having a first output for controlling the gain of the
center front channel and a second output for controlling the gain
of the other channels in response to settings of the volume
control, the gain of the center front channel having a first
relationship to the volume control settings and the gain of the
other channels having a second relationship to the volume control
settings, the relationships being such that for a range of volume
control settings less than a first setting the gain of the center
front channel (1) remains substantially constant while the gain of
the other channels decreases as the setting decreases, or (2)
decreases more gradually than the gain of the other channels as the
setting decreases..].
.[.2. A motion picture soundtrack reproduction system, comprising a
center front soundtrack channel and a plurality of other soundtrack
channels, each of said channels having adjustable gain and one or
more loudspeakers, and a controller having a volume control for
adjusting the gain of all the channels, the volume control having a
range of settings from a minimum to a maximum, the controller
having a first output for controlling the gain of the center front
channel and a second output for controlling the gain of the other
channels in response to settings of the volume control the gain of
the center front channel having a first relationship to the volume
control settings and the gain of the other channels having a second
relationship to the volume control settings, the relationships
being such that for a range of volume control settings less than a
first setting the gain of the center front channel (1) remains
substantially constant while the gain of the other channels
decreases as the setting decreases or (2) decreases more gradually
than the gain of the other channels as the setting
decreases..].
.[.3. A system according to claim 1 or claim 2 wherein the range of
volume control settings less than said first setting extends down
to the minimum control setting..].
.[.4. A system according to claim 1 or claim 2 wherein the range of
volume control settings less than said first setting extends down
to a second setting above the minimum control setting..].
.[.5. A system according to claim 3 wherein for settings less than
said second setting the gains of all the channels decrease in
substantially the same way as the setting decreases and for such
volume control settings the gain of the center front channel is
greater than the gain of the other channels..].
.[.6. A system according to claim 5 wherein for settings less than
said second setting the gain of the center front channel is greater
than the gain of the other channels by a substantially constant
amount in the logarithmic domain..].
.[.7. A system according to claims 1 wherein for settings greater
than said first setting the gains of all the channels increase as
the setting increases and for each of such volume control settings
the gain of the center front channel and the gain of the other
channels are substantially the same..].
.[.8. A system according to claims 1 wherein when the volume
control is set to a standard setting, each of the channels has a
respective gain that produces a respective standard acoustic level
in response to a signal having a respective standard reference
level in the channel..].
.[.9. A system according to claim 8 wherein said first setting is
about said standard setting..].
.Iadd.10. An audio system, comprising: a first channel and a second
channel, each of said channels having a gain; a controller having a
volume control for adjusting the gain of the first channel and the
gain of the second channel, the volume control having a range of
settings from a minimum to a maximum, the gain of the first channel
having a first relationship to the volume control settings and the
gain of the second channel having a second relationship to the
volume control settings, the relationships being such that for a
range of volume control settings less than a first setting the gain
of the first channel (1) remains constant while the gain of the
second channel decreases as the volume control setting decreases
below said first setting or (2) decreases more gradually than the
gain of the second channel as the volume control setting decreases
below said first setting; a matrix decoder to derive a first
channel output and a second channel output..Iaddend.
.Iadd.11. The audio system of claim 10, wherein the range of volume
control settings less than said first setting extends down to the
minimum control setting..Iaddend.
.Iadd.12. The audio system of claim 10, wherein the range of volume
control settings less than said first setting extends down to a
second setting above the minimum volume control
setting..Iaddend.
.Iadd.13. The audio system of claim 12, wherein for volume control
settings less than said second setting the gains of the first and
second channels are attenuated equally as the volume control
setting decreases below said second setting and for such volume
control settings the gain of the first channel is greater than the
gain of the second channel..Iaddend.
.Iadd.14. The audio system of claim 10, wherein the matrix decoder
derives the first channel output and the second channel output from
a two-channel soundtrack..Iaddend.
Description
TECHNICAL FIELD
The invention relates generally to the processing of audio signals.
More particularly, the invention relates to control of the loudness
of motion picture soundtracks when reproduced.
BACKGROUND ART
In the mid-1970s, Dolby Laboratories introduced a calibration
recommendation for monitor levels in movie soundtracks ("Dolby" is
a trademark of Dolby Laboratories, Inc.). A pink noise reference
signal was used in the record chain to adjust the audio monitor
level to 85 dBc. All theatres equipped for playback of the new
stereo optical soundtracks were set up such that an equivalent pink
noise signal in a soundtrack channel generated the same 85 dBc with
the playback volume control (fader) set to the calibrated setting.
This meant that theatres playing films at the calibrated volume
control setting (a setting of "7" in a range of "0" to "10" on most
cinema processors) reproduced the same loudness level selected by
the film director and audio engineers in the dubbing theatre
(referred to herein as "the mixer").
This system worked quite well for many years. Dolby Stereo (A-type
encoded) films had limited headroom and the resulting constrained
dynamic range yielded few audience complaints. Most theatres played
films at the calibrated level. Soundtrack format technology has
been significantly enhanced since Dolby Stereo. Dolby SR extended
the headroom by 3 dB at midrange frequencies, and more at low and
high frequencies. In recent years, the new digital formats have
further increased the headroom. FIG. 1 shows maximum sound pressure
level of one reproduced soundtrack channel versus frequency for
four photographic soundtrack formats, Academy mono, Dolby A-type,
Dolby SR and Dolby Digital. The curves are normalized with respect
to their reference levels. Thus, they show the maximum sound
pressure level that one channel of each different optical
soundtrack system is capable of when playing a motion picture at
the calibrated volume control setting in a properly set up theater.
The maximum sound pressure level in a theater is also a function of
the number of soundtrack channels. For example, five channels can
deliver 2.5 times as much power as two channels, resulting in an
increase of 4 dB in sound pressure level. Thus, in the case of five
or seven channel digital soundtrack reproduction, for example, the
increase in peak sound pressure level is even greater than that
shown in FIG. 1.
Because the 85 dBc calibration technique has been maintained
throughout evolving format changes, additional headroom is
available on the newer soundtracks. However, feature films do have
a consistent, subjective mix reference, independent of increased
headroom, for dialogue record level, known as "associative
loudness." When the dubbing mixer sees an actor on the screen, and
there is no conflict between the dialogue and music or effects, the
dialogue level in a moderate close-up is set to be plausible for
the visual impression. Within reasonable limits, this generally
holds true to within 2 or 3 dB. This natural dialogue level does
not hold true for narration, as there is no corresponding visual
reference. Music and effects have no direct visual associative
loudness. Most people are not familiar with the actual sound
pressure levels of a Concorde takeoff or a 50 mm howitzer. The
music score level is equally uncalibrated.
As the headroom capability of the recording medium has been
extended, it has certainly been used: the "non-associative"
loudness of effects and music has risen to fill the available
headroom space. Using dialogue as a reference, loud sounds like
explosions are often 20 dB or more louder (explosions reach full
scale peak level of 25 dB above dialogue level), and some quiet
sounds, which are intended to be heard by all listeners, such as
leaves rustling, may be 50 dB quieter.
In response to audience complaints that movies are too loud, many
theatres are playing films substantially below the calibrated
level. A volume control setting (fader level) of "6" or "51/2," as
opposed to the calibrated level (volume control standard setting)
of "7," is not uncommon, representing a loudness reduction of
approximately 4 or 6 dB. Some cinemas have their volume control
permanently turned down to such settings because projectionists
operating multiplexes with many screens showing different movies
simultaneously don't have the time or cannot be bothered to set the
controls differently for different movies. If the volume control is
turned down to avoid complaints of excessive loudness, the dialogue
is quieter than the mixer intended, and audiences may complain
instead that some dialogue is not intelligible in the presence of
other sounds in the film and/or general background noise of the
theater (popcorn eating, air-conditioning, people talking, etc.).
Theatre playback levels are often set by complaints generated by
the loudest (and earliest) element of the show. If the playback
level is set in response to the loudest trailer (preview), which is
often louder than the feature film, the feature often plays at the
same reduced level. The result is that the dialogue level of the
feature is lowered by the same level deemed necessary to attenuate
the trailer. A feature film played with a loudness 6 dB below the
calibrated level may have serious dialogue intelligibility problems
and very quiet sounds may become inaudible.
In addition, it is possible that the increased use of headroom from
Dolby A-type to Dolby SR and digital releases has not been matched
by a corresponding increase in power amplifier and loudspeaker
capability. The resultant distortion from overloaded equipment may
well exacerbate the loudness problems of recent soundtracks,
causing increased incidence of complaints.
In early cinema sound equipment employing calibration, the volume
control was a mechanical potentiometer, often with a click-stop or
detent at the standard setting. More recent (digital) equipment
uses a shaft encoder or a pair of up-down buttons (with a numeric
display for the setting), delivering a control signal that operates
on multipliers (either digital or voltage-controlled amplifiers) to
affect the gain applied to all channels of the reproduced
soundtracks. In typical cinema sound equipment, the volume control
varies the gain gradually and relatively uniformly over a range of
settings from about "4" to "10," with the gain falling more rapidly
at setting below about "4," allowing a fade to inaudibility. Such a
typical prior art relationship between gain or loss and volume
control setting is shown in the lower curve of FIG. 2, described
below.
With the exception of monophonic installations, to which the
present invention does not apply, all movie sound installations
include three or more front loudspeakers including a center front.
Historically, film mixers place dialogue in the center front
channel and it is rare for speech from an on-screen actor to be
placed anywhere else. This applies both for a multitrack digital
soundtrack (for instance 5.1- or 7.1-channels) or a two-channel
analog optical soundtrack reproduced via a matrix decoder to derive
left, center, right and surround outputs. The center front channel
may of course contain other material, but, generally, it is
material important in following the action of the movie because the
audience's attention is focused on the screen. At moments when the
soundtrack is loud enough to provoke complaint, several channels
are generally contributing to that loudness, not just any one, and
in particular not just the center front.
DISCLOSURE OF INVENTION
In accordance with the present invention, a motion picture
soundtrack reproduction system comprises a center front soundtrack
channel and a plurality of other soundtrack channels. A volume
control adjusts the gain of all the channels, the volume control
having a range of settings from a minimum to a maximum, the gain of
the center front channel having substantially a first relationship
to the volume control settings and the gain of the other channels
having substantially a second relationship to the volume control
settings, the relationships being such that for a range of volume
control settings less than a first setting the gain of the center
front channel remains substantially constant while the gain of the
other channels decreases as the setting decreases or decreases more
gradually than the gain of the other channels as the setting
decreases.
Also in accordance with the present invention, a motion picture
soundtrack reproduction system comprises a center front soundtrack
channel and a plurality of other soundtrack channels, each of the
channels having adjustable gain and one or more loudspeakers, and a
controller having a volume control for adjusting the gain of all
the channels, the volume control having a range of settings from a
minimum to a maximum, the gain of the center front channel having a
first relationship to the volume control settings and the gain of
the other channels having a second relationship to the volume
control settings, the relationships being such that for a range of
volume control settings less than a first setting the gain of the
center front channel remains substantially constant while the gain
of the other channels decreases as the setting decreases or
decreases more gradually than the gain of the other channels as the
setting decreases.
The range of volume control settings less than the first setting
extends down to the minimum control setting or, alternatively, down
to a second setting above the minimum control setting. In the
latter case, for settings less than the second setting the gains of
all the channels decrease in substantially the same way as the
setting decreases and for such volume control settings the gain of
the center front channel is greater than the gain of the other
channels. Optionally, for settings less than the second setting the
gain of the center front channel is greater than the gain of the
other channels by a substantially constant amount in the
logarithmic domain.
For settings greater than the first setting the gains of all the
channels may increase as the setting increases and for each of such
volume control settings the gain of the center front channel and
the gain of the other channels may be substantially the same.
The invention is particularly advantageous in an arrangement in
which when the volume control is set to a standard setting, each of
the channels has a respective gain that produces a respective
standard acoustic level in response to a signal having a respective
standard reference level in the channel. In that case, the first
setting is about the standard setting.
The invention provides for reducing the maximum loudness, and
thereby avoiding complaints, while maintaining the acoustic level
of the center front containing dialogue and requiring only one
user-operated control. According to an embodiment of the invention,
the cinema equipment is designed and installed in the conventional
manner to the extent that with the volume control nominally at its
standard setting, each of the reproduced soundtrack channels has a
respective gain that produces a respective standard acoustic level
in response to a signal having a respective standard reference
level in the channel, thus matching the standard levels in a film
mixing room. Thus, when calibrated, the playback system with its
volume control at the standard setting has an apparent loudness
that is substantially the same as that intended by the film mixer.
However, in accordance with the present invention, if the volume
control is turned down below the standard setting in response to
actual (or expected) complaints from the audience, over a limited
range of settings all channels except the center front are
attenuated equally, but the center front is reduced by a smaller
degree (or not at all). The effect is not only a reduction in the
overall loudness but an increase in the proportionate contribution
of the center front channel, with a potential improvement in
intelligibility when the other channels are loud. Optionally, after
some degree of changing the balance of the center front to other
channels down to a setting below the standard setting, for further
lowering of the settings all channels are attenuated equally,
maintaining fixed the altered balance.
BRIEF DESCRIPTION OF DRAWINGS
FIG. 1 shows maximum sound pressure level versus frequency for four
photographic soundtrack formats, Academy mono, Dolby A-type, Dolby
SR and Dolby Digital.
FIG. 2 shows one set of suitable relationships between gain of the
center front soundtrack channel and gain of each of the other
soundtrack channels versus volume control setting, in which a gain
of 0 dB is obtained for the standard volume control setting.
FIG. 3 is a simplified block diagram showing an implementation of
the present invention from a structural standpoint.
FIG. 4 is a simplified block diagram showing an implementation of
the present invention from a functional standpoint.
BEST MODE FOR CARRYING OUT THE INVENTION
FIG. 2 illustrates idealized curves of gain/loss as a function of
volume control setting, for the center front channel (upper line)
and for each of the remaining channels (lower line). The lower line
also shows the typical gain/loss for all channels (rather than
channels other than the center front channel, as in the present
invention) as a function of volume control setting in prior art
motion picture sound equipment. While the characteristic responses
shown in the example of FIG. 2 are practical and useful ones, the
precise characteristics are not critical. For example, the lower
characteristic curve need not be the same as in the prior art
gain/loss for all channels versus volume control setting The
characteristics shown in the figures are just one example of
suitable characteristics that fall within the scope of the
invention
Still referring to FIG. 2, it will be seen that the gain of the
center front channel has a first relationship to the volume control
settings and that the gain of each of the other channels has a
second relationship to the volume control settings. In FIG. 2, 0 dB
is defined as the gain with the volume control at a first setting,
the standard "7" setting. As shown in FIG. 2, for settings less
than the first setting down to a second setting, the gain of the
center front channel decreases more gradually than the gain of the
other channels as the setting decreases. Alternatively, over a
limited range of settings just below the standard setting, for
instance between a setting of "7" and a setting of "6," the center
channel gain may be constant as the gain of the other channels
changes. Although such changes in gain (either alternative) may
extend down to the minimum volume control setting, in a practical
embodiment such changes in gain preferably do not extend down to
the minimum setting but rather to a second setting, which may be a
setting of about "5," for example, as shown in FIG. 2. In that
case, for settings below the second setting, the gains of all the
channels decrease in substantially the same way as the setting
decreases and for such volume control settings the gain of the
center front channel is greater than the gain of the other channels
by a few dB, for example, as shown in FIG. 2. Preferably, for
settings above the nominal standard setting up to a maximum
setting, the gains of all the channels increase as the setting
increases and for each of such volume control settings the gain of
the center front channel and the gain of the other channels are
substantially the same. It should be understood that the
relationships between the gain of the center front channel, on one
hand, and the gain of the other channels, on the other hand, versus
the volume control settings need not be precisely in accordance
with the examples of FIG. 2, but are to be limited only by the
scope of the appended claims.
An exemplary system according to the present invention is shown in
FIG. 3. A center front soundtrack channel has a gain adjuster 102
that controls the gain of the channel. The channel feeds one or
more loudspeakers 104 via a power amplifier (not shown). In
practice, the gain adjuster 102 may be, for example, the gain or
volume control of a preamplifier or a passive variable loss at the
output (preferably the output rather than the input) of a
preamplifier. A plurality of other channels, shown for simplicity
as two channels, each has a respective gain adjuster 106 and 108.
Each channel feeds one or more respective loudspeakers 110 and 112
via respective power amplifiers (not shown). The gain adjuster 102
for the center front channel is controlled by a first output of a
controller 114 and the gain adjusters 106 and 108 for the other
channels are controlled by a second output of controller 114, in
the manner described herein in response to the setting of the
controller's volume control 116.
In a practical arrangement employing digital controls, as shown in
FIG. 4, the volume control setting may select values in first and
second lookup tables 202 and 204. The first lookup table 202 in
turn may adjust a multiplier controlling volume 206 in the center
front channel, while the second lookup table 204 may adjust
multipliers controlling volume 208 and 210 in the other channels.
Lookup table values in response to volume control settings may be
chosen so as to provide the desired relationships between gains in
the various channels versus setting.
The present invention and its various aspects may be implemented in
analog circuitry, for example, with two suitable non-linear
functions relating control setting to gain, or as software
functions performed in digital signal processors, programmed
general-purpose digital computers, and/or special purpose digital
computers, or some combination of such devices and functions.
Interfaces between analog and digital signal streams may be
performed in appropriate hardware and/or as functions in software
and/or firmware.
* * * * *