WO2015185406A1

WO2015185406A1 - Dynamic configuring of a multichannel sound system for power saving

Info

Publication number: WO2015185406A1
Application number: PCT/EP2015/061679
Authority: WO
Inventors: Gorm Haldor JØRGENSEN; Søren Borup JENSEN
Original assignee: Bang & Olufsen A/S
Priority date: 2014-06-02
Filing date: 2015-05-27
Publication date: 2015-12-10
Also published as: DK178063B1

Abstract

The present invention relates to a method and system for dynamic configuring an audio reproduction system comprising two or more sound channels. The aim of this dynamic configuration of the number of active channels is to reduce and optimize the power consumption in the active channels. The premises of the configuring and reconfiguring of number of active channels are based on conditions based on user perceptions listening to an actual audio source. The configuring means are based on a digital signal processor that configures the sound channels and optionally controls the same by adjusting the equalization, the delay and the gain.

Description

DYNAMIC CONFIGURING OF A MULTICHANNEL SOUND SYSTEM FOR POWER SAVING

The present invention relates to a method and system for dynamic configuring an audio reproduction system comprising two or more sound channels. The aim of this dynamic configuration of the number of active channels is to reduce and optimize the power consumption in the audio system including the active channels. The premises of the configuring and reconfiguring of number of active channels are based on conditions based on user perceptions listening to an actual audio source.

The configuring means are based on a digital signal processor that configures the sound channels and optionally controls the same by adjusting the equalization, the delay and the gain.

In modern media rendering system including multichannel audio systems it's becoming a demand to operate these types of systems at the lowest level of power consumption. This due to the facts:

• A standard multichannel system may be enabled with 20 or more channels, each controlled individually with audio control means and active

loudspeaker amplifiers powered individually.

· More and more sound systems are battery powered applications, e.g. in a car, thus having limited power resources available.

A prior art system is disclosed in US 2014/0146970, where techniques are described for a collaborative sound system. In this system, mobile devices each including a loudspeaker are configured and may as such participate in a

collaborative surround sound system. Mobile devices having "low battery status", are fully - or partly excluded from being member of the collaborative system, as they cannot deliver a required output level as rendering device. Contrary the above, the present invention configures according to available resources and to accommodate to a certain volume level, as requested by the user, all with the aim of power saving.

Different aspects of power consumption are interesting to be candidates for power saving:

• a general power consumption when the system is idle, i.e. no play back is active from any media file.

• a variable setup of the configuration of active channels according to an actual need.

It's a well known problem in prior art loudspeaker systems operating in closed rooms/spaces e.g. a car, that the sound expired by the user may vary according to the listeners position in a space relative to the loudspeaker system transducers, and in addition to environmental noise, and provided sound level and music content.

Thus, to minimize power consumption and to obtain a certain perceived quality level of a loudspeaker system, e.g. in a car, the individual sound channels incorporating one or more loudspeaker modules must be activated/deactivated and calibrated and adjusted individually and according to above mentioned premises. A first aspect of the invention is:

a method and a system to obtain power saving in an audio reproduction system comprising two or more sound channels where the power saving is enabled in an automatically configuring procedure having the steps:

· determine each of the available sound channels means,

• based on a user selection of an actual sound source to be rendered to the user via an audio reproduction system at least one of the sound channel means is enabled,

• based on one or more events perceived by the user and related to one or more perceptual conditions, one or more additional sound channel means are enabled or disabled.

The invention discloses a surround sound system where different sound settings may be enabled via digital signal processing means controlling the individual sound channels parameters e.g. the equalization (filters), the delay, the gain (amplification).

A second aspect of the invention is a perception optimized condition, source material content and channel selection or shutdown and where the perceptual conditions include:

• audio source content characteristics like speech and/or music;

• audio play back characteristics like surround sound, volume, balance, bass and/or treble levels;

• environmental characteristics like noise level;

· room characteristics like size/volume of the room and position and number of listeners in the room;

• audio source content characteristics like meta data and other context related information. The invention discloses a solution that in an automatically mode of operation may fulfil the stated requirement "perceived optimized condition and source material dependent channel activation and shutdown".

In summary the invention includes:

· sensor means to detect the presence of a listener;

• sensor means to detect environmental noise;

• sound system modes of operation i.e. sound level from low to high;

• sound system adjustments i.e. treble, bass and balance;

• a mode of operation related to a user position or a required function e.g. driver, front, rear, and all;

• information available according to music content (voice, music, surround);

• multi channel sound system, e.g. two channels stereo, or a 5.1 surround sound system;

• digital controlled sound system e.g. digital control of gain, equalization and delay;

• active speakers including amplifiers and filters for each loudspeaker

transducer,

• control means to enable or disable sound rendering means to be become active or in-active.

The digital control of the sound system is based on standard means for: • gain: adjust the signal by a certain level, e.g. +0.1 dB;

• delay: the signal is delayed by a specific time, e.g. 100 ms;

• EQ: the signal is filtered according to the Finite Impulse Response

principle (FIR) or the signal is filtered according to the Infinite Impulse Response principle (iiR); a number of coefficients are specified; the number of parameters typically to be from 1 > 1000.

The invention may be implemented in different embodiments, in which the alternative reconfiguring procedures may be implemented as:

· a traditional algorithm in terms of a sequential software program in which the values of the resulting adjustment parameters and channel

activation/deactivation are embedded in the code itself; the algorithm validates according to a specified system structure of an actual

loudspeaker configuration;

· a table based concept in which one or more tables defines the attributes to be applied per loudspeaker channel versus e.g., but not limited to, the power mode of operation, the listener position and content related information. According to specific requirements of a sound providing system miscellaneous features may be offered and controlled automatically and/or commanded by the user. The features may be used individually and/or mixed in a way that

accommodates the user demands. A predefined combination of cannel selection and sound settings per channel and the functional options supports the processing.

Examples of functional options are:

• seat priority: driver, all, back, front, centre, left, right etc.;

• a persons physical position: in a room, in a car, in a PA domain etc.;

· zone priority: a zone includes one or more specific sound channels;

• mode priority: movie, music, speech;

• individual channel selection, activation and deactivation;

• channel mode: stereo, surround sound 5.1 , or other multi channel system of any order;

· group of people: one or more listeners in a zone;

• content of media voice, music, type of music e.g. genre.

• Sound rendering system adjustment like volume, balance, loudness,

timbre and bass. The configuring/reconfiguring process is provided as one or more algorithms to provide the calculation of each of the values of the sound channel selection and adjustment variables.

In the preferred embodiment the reconfiguring process is provided as a table with relations provided to be accessed by the digital signal processor to provide each of the values of the sound channel adjustment variables.

The saved attributes and key parameters are loaded into the reconfiguring means supported by electronically means, means that is connected wirelessly or connected wired to the audio reproduction system. In a third aspect of the invention the reconfiguring process provides the settings of the sound parameters; gain, equalization and delay for one sound channel, to be applied in one sound field zone related to the physical position of first group of people including one or more listeners.

In yet another aspect a person position is detected via standard sensor means like switches or infrared detectors or strain gauges or temperature sensitive detectors.

The configuring process is to be automatically executed and/or controlled by the audio amplifier means, including a digital signal processor, which drives the loudspeaker system. The reconfiguring means is embedded into an audio reproduction system.

In a preferred embodiment, the reconfiguring is controlled via a table mapping the mode of operation to adjustment parameters for each speaker in every channel or just relevant channels. The adjustment parameters are e.g. but not limited to: equalization, delay and gain.

This feature enables the option that in one configuration of selected channels to be active one set of parameters may be relevant in each of these channels and in another configuration of selected channels to be active another set of parameters may be relevant. E.g. channel one parameters may be defined with one set of data if channel two is active at the same time, and channel one parameters may be defined with another set of data if channel three is active at the same.

The table may be represented as one or more data set as most appropriate to the digital controller unit.

E.g. one data set may contain the relations among:

• listener positions (center, front, back, middle, all, left/right),

· loud speaker channel #,

• sound level (off, low, medium, high).

Another data set may contain the functional/mode related information like:

• functional settings (movie, audio only) ,

· media/music content (voice, music, surround, video)

• loud speaker channel #,

• parameter settings (EQ, delay, and gain).

Yet another data set may contain the channel configurations:

· examples of loud speaker channels,

o Center,

o TweeterFrontLeft (TFL),

o MiddleFrontLeft (MFL),

o WooferFrontLeft (WFL),

o TweeterFrontRight (TFR)

o MiddleFrontRight (MFR),

o WooferFrontRight (WFR).

o MiddleRearLeft (MRL),

o MiddleRearRight (MRR),

o WooferRearRight (WRR),

o WooferRearLeft (WRL). • examples of channel configurations:

o Center, TFL,WFL

o Center, TFL,WFL,TFR, MFR, WFR

o Center, TFL,WFL,TFR, MFR, WFR, WRR, WRL, MRR, MRL.

This table concept is considered to be a data driven control systems, and enables for easy updates of the functional behaviour of a specific system simply by loading alternative data set into the controller. In addition, the invention includes a Constraint Solver (CS), which comprises a table with digital data representing the constraints of the passenger positions and related acoustical adjustment, attributes and corresponding variable values.

The constraint solver processing enables an arbitrary access mode to information with no order of sequences required. This is an important advantage over prior art tree-like programming structure, where the starting point is given by the root of the tree. Especially, when finding ways from nodes within the tree-like program to a specific target location in the tree, it may be obscure with regard to which way to choose, whether backwards or forward, and the final solution may be a new start from the root.

According to the invention, the product configuration domain table is organized as relations among variables in the general mathematical notation of 'Disjunctive Form':

AttribVariable 1.1 and AttribVariable 1.2 and AttribVariable 1.3 and AttribVariable 1 .n Or AttribVariable 2.1 and AttribVariable 2.2 and AttribVariable 2.3 and AttribVariable 2.n

Or

Or AttribVariable m.1 and AttribVariable m.2 and AttribVariable m.3 and AttribVariable m.n

For example, AttribVariable 1 .1 defines people position, AttribVariable 1 .2 defines music content, AttribVariable 1 .3 defines environment and AttribVariable 1 .n defines channels configuration.

In another example, AttribVariable 2.n may be a reference to another table.

With this method of defining the problem domain, it becomes a multi-dimensional state space enabling equal and direct access to any point in the defined set of solutions. The term multidimensional has to be understood as a contrast to a treelike programming structure, which is two-dimensional.

Alternative configurations may be evaluated by the CS, the alternatives being one or more of the defined set of legal combination in the constraint table.

The example illustrates alternative solutions for x, y when y is given: The: If x Then y may be represented as x -> y

With the truth table: x x -> v

0 0 1

0 1 1

1 0 0

1 1 1

Given the premise x is Ί ' the conclusion y is Ί '. Given the conclusion y is Ί ' the premises for x may be "Tor Ό'.

Thus, when y is Ί ' the alternatives for x are Ί ' or Ό'.

Represented in a constraint table the x -> y has the legal combinations of x, y:

x Y.

0 0

0 1

1 1 Table entries in a constraint table may be combined into legal/illegal combination such that all the well known logical operators known from the Boolean algebra will be included as required. The logical operators being: AND, OR, NOT, XOR, Logical Implication (->), Logical Bi-implication (=). An example of a table definition for an activation of individual channels is given below:

An example of a table definition for an adjustment of individual channel

parameters is displayed below:

Mode or Speaker Other (e.g. Equalization Delay Gain

position channel # time, content) EQ

Driver 1 p-val-d1 q-val-d1 r-val-d1

2 p-val-d2 q-val-d2 r-val-d2

n p-val-dn q-val-dn r-val-dn

Front 1 p-val-f1 q-val-f1 r-val-f1

2 p-val-f2 q-val-f2 r-val-f2

n p-val-fn q-val-fn r-val-fn

Rear 1 p-val-r1 q-val-r1 r-val-r1

2 p-val-r2 q-val-r2 r-val-r2

n p-val-rn q-val-rn r-val-rn

All 1 p-val-a1 q-val-a1 r-val-a1

2 p-val-a2 q-val-a2 r-val-a2

n p-val-an q-val-an r-val-an

Movie 1 p-val-m1 q-val- r-val-m1

m1

2 p-val-m2 q-val- r-val-m2

m2 n p-val-mn q-val- r-val-mn

mn

Other 1 p-val-o1 q-val-o1 r-val-o1

2 p-val-o2 q-val-o2 r-val-o2

n p-val-on q-val-on r-val-on

Thus in an aspect of the invention the reconfiguring means is embedded into an audio reproduction system. Thus the system becomes the controller of the re- configuring process that provides a reconfiguration of the system itself.

In the following, preferred embodiments of the invention will be described with reference to the drawings wherein: Figure 1 displays components that constitute a conceptual model of the

invention;

Figure 2 displays an example of an embodiment of the invention displaying a plurality of sound channels in a sound system. Figure 1 display components that constitute examples of a media rendering system including control of actual sound channel amplifiers to be enabled or disabled.

Control means (10) being included into a media rendering system may select one or more amplifier channels (1 1 ) to be activated or deactivated according to criteria as perceived by the user (18).

A configuration table (12) is configured with data including actual status of any of the one or more channels, and optionally with actual values for parameters for equalization, delay and gain per channel.

These data may be pre-set and updated dynamically during operation according to actual system requirements.

In a high quality audio reproduction system a dedicated filter means, an equalizer is provided per amplifier. The means (3) provides a frequency dependent amplification to control the overall gain, which may be regulated up or down as required.

This feature enables for adjustment of one channel to relate to another channel, e.g. to control the sound distribution into individual zones of sound fields, such that the sound delay among channels can be controlled.

The premises for the channel selection criteria are based on:

• sensor readings (14) , this being environmental related e.g. noise,

• user (18) manual selection,

• content related media information (16) in streams, files and alike.

A constraint data table (15) defines the relationship among premises and corresponding conclusion to make; specifically about which channels (1 1 ) must be activated or deactivated according to the situation perceived by the user (18). These constraint data may be pre-set and updated dynamically during operation according to actual system requirements. Figure 2 displays the example of an audio reproduction system comprising loudspeaker modules configured in a multi channel concept e.g. a 5.1 surround sound system.

Basic system components are displayed like loudspeaker transducer, amplifier, equalization means, delay (1 ,2,3,4).

In fact any number of channels (22) may be handled; having a corresponding table complex related according to the actual functional system requirements. The audio reproduction system may be an audio amplifier (20), including a digital signal processor, to controlling and driving the loudspeaker channels (22), and to provide a signal (21 ) that's amplified and filtered and delayed accordingly.

Input from sensor means (23) determines the mode and functional operation of the control system and may be of different nature e.g. but not limited to: simple switch, accelerometer, infrared detection, thermal sensing, noise (microphone) etc.

In the preferred embodiment the sensors primarily detects the position of a user in a room/space, the position to be related to the sound field that's relevant for the one or more users /listeners.

E.g. in a vehicle the detection of a user position is where the individual users are seated. The detection in this system may be via a simple switch in every seat, or via switches related to the security belts.

Additional control signals may be received as user commands (24), e.g. a command to 'enable automatic sound control' and content/context related information (25), e.g. information about the time of the day and/or the type of music actual in play. This additional control signal information to be used as input into the digital signal processor to control mode and functional operation of the sound system.

The content sensing is primarily to detect on the incoming media input the type of audio which is received, e.g. voice/speech or music.

In a preferred embodiment the configure/reconfigure means is imbedded into the controller of the audio sound system. Thus the audio sound system is the master having the digital signal processor means (20) that initiates, controls and applies the reconfiguring process. Alternative table definitions may be loaded into the digital signal processor (20) from external means e.g. a laptop/PC (26).

The invention may be applied in relation to automatically adjusting an audio sound system to a maximum level of quality as perceived by the user.

The invention includes sound channel configurations to be applied in surround sound systems and traditional stereophonic system, and to be applied in any domain like a home, in a vehicle, in an airplane in a boat, in an office or in any other public domain and alike.

Claims

1 A method to obtain power savings in an audio reproduction system

comprising two or more sound channels wherein the power saving is enabled in a configuring procedure having the steps:

• determining each of the available sound channels means,

• enabling at least one of the sound channel means based on a user selection of an actual sound source to be rendered to the user via an audio reproduction system,

• enabling or disabling one or more additional sound channel means based on one or more events perceived by the user and related to one or more perceptual conditions, and wherein the perceptual conditions include audio source content characteristics like speech and/or music, and a user selected volume level, and include environmental characteristics like noise level, and include room characteristics like size/volume of the room and position and number of listeners in the room and audio source content characteristics like meta data and other context related information and characterized in that the configuring procedure is a constraint solver, that finds one or more legal combination(s) among all the defined set of legal combinations of the one or more sound channels means as defined in a table.

2. A method according to claim 1 , wherein the configuring procedure provides the settings of the sound parameters: gain, equalization and delay for each of the one or more sound channels.

3. A method according to claim 2, wherein the configuring procedure provides the settings of the sound parameters gain, equalization and delay for one channel by relating to the sound parameters gain, equalization and delay for another channel.