EP3090575A2

EP3090575A2 - Method for audio reproduction in a multi-channel sound system

Info

Publication number: EP3090575A2
Application number: EP14851410.2A
Authority: EP
Inventors: Gunnar Kron
Original assignee: Kronoton GmbH
Current assignee: Kronoton GmbH
Priority date: 2014-01-05
Filing date: 2015-01-02
Publication date: 2016-11-09
Anticipated expiration: 2035-01-02
Also published as: WO2015101413A2; DE102014100049A1; EP3090575B1; US11153702B2; US20170026768A1; DE202014010599U1; US20220070602A1; KR20170004952A; US11722831B2; KR102332913B1; WO2015101413A3

Abstract

The invention relates to a method for reproducing audio in a multi-channel sound system including two input signals (L and R), wherein output signals are generated for different sound perception levels. In order to develop said method in such a way that audio can be reproduced within a larger range of applications in a multi-channel sound system, according to the invention, only a lower sound perception level (7) and a higher sound perception level (6) are generated, and a maximum of six output signals are generated, a maximum of two output signals being allocated to the lower sound perception level (7) and a maximum of four output signals being allocated to the higher sound perception level (6).

Description

Method for audio playback in a multi-channel sound system

The invention relates to a method for audio reproduction in a multi-channel sound system with two input signals L and R, in which output signals for different listening levels are generated.

Methods of the type mentioned in the beginning are known to the person skilled in the art and represent a further development of a conventional surround sound, an audio reproduction which is only at the ear level, ie. plays on the lower listening level.

In three-dimensional audio playback in a multi-channel sound system, a higher listening level is added to the lower listening level. This is also the significant advantage of the method of the aforementioned type, since the human ear can clearly perceive and differentiate upwards staggered sounds, so that the listener can benefit from an extended sound experience through three-dimensional loudspeaker arrangements. Methods of the type mentioned above have been developed mainly for sound signals in large rooms, such as in movie theaters.

In the prior art, different views are presented as to which speaker configurations or mode of generating the three-dimensional sound, whether channel or object-based, lead to an optimal sound experience, either multi-channel recording and reproduction of a three-dimensional sound space, as in WO 01/47319 A2 or the upmix of variable input channels offered by various providers to form a three-dimensional sound space in the foreground of the considerations. For example, Dolby Laboratories' three-dimensional audio systems have up to 64 speakers (e.g., Dolby Atmos), which in turn requires a corresponding number of output signals

All methods of the type mentioned above, it is common that a

CONFIRMATION COPY Complex speaker configuration and thus a corresponding increased number of output signals is required to generate the desired three-dimensional sound space.

Even a loudspeaker configuration in a 9.1 three-dimensional sound system, which is suitable for a home theater, for example, consists of ten loudspeakers, which in turn requires a corresponding number of output signals for the lower and upper listening levels.

However, according to the current state of the art, the consumers accustomed to AV devices (audio video devices) find it very difficult to enjoy the advantages of three-dimensional audio reproduction, since only a few are left to expensive equipment with three-dimensional audio reproduction and only a limited number of consumers have the appropriate premises in which it is possible to realize an increased number of loudspeakers including wiring. The reality is that while cinemas, music studios or even selected concert halls have the technology of three-dimensional audio playback, but it does not enter the everyday life of those who simply and easily, for example, at the workplace or in the living room or traveling with little effort and comparatively low budget in the advantage of three-dimensional audio playback.

It is therefore an object of the invention to develop a method of the type mentioned in such a way that these disadvantages are eliminated.

This object is achieved with the features of claim 1. Advantageous embodiments of the invention will become apparent from the dependent claims.

The invention provides that only a lower hearing level and only one upper hearing level are generated, wherein a maximum of six output signals are generated with a maximum of two output signals for the lower listening level and ma- ximal four output signals for the upper listening level.

The core idea of the invention is to provide a method which, while generating a minimum number of output signals, can reflect a three-dimensional audio reproduction and at the same time covers both the mono and the stereo region.

This results in a smallest unit, which can preferably be extended in a modular manner by the output signals serve as further input signals to further lower and upper listening levels and thus to produce an even more complex speaker configuration.

By means of the method according to the invention and the software corresponding thereto, it is possible, for example in domestic televisions or laptops, to realize the increased sound level by adding two small loudspeakers.

An advantageous embodiment of the invention provides that from the provided for the input signals R and L input channels channels are decoded. These channels are preferably a left-hand spatial channel RL = L-R, a right-hand spatial channel RR = R-L and a center channel C = L + R. Expediently, linear and parallel channels R and L are generated from these input channels for these decoded channels, which channels preferably serve as output channels for the lower listening level. Practical variants of the invention provide that stereo signals or mono signals are generated for the signals in the lower and upper listening levels.

A device with audio input and audio output channels and a processor, wherein the processor associated speakers is the subject of claim 10, wherein on the processor is a software ported containing an algorithm that is executed by the processor, wherein the algo- Rithmus the method according to one of claims 1 to 9 detected.

The invention also provides software residing on a signal processor, i. ported on the signal processor. The software contains an algorithm which is processed by the signal processor, the algorithm detecting the method.

In the following the invention will be explained in more detail with reference to the drawings. It shows in a schematic representation:

1 shows a speaker arrangement of a 3D sound format with different listening levels according to the prior art,

2 shows a method according to the invention,

3 to 8 different embodiments of audio-video devices, in which a method of FIG. 2 is integrated,

Fig. 9 to 1 1 further embodiments of the invention

Procedure and

12 shows a device into which a method according to the invention according to the embodiment in FIG. 11 is integrated.

FIG. 1 shows a conventional three-dimensional audio reproduction in a larger space 2 occupied by a listener 3 in the context of a 9.1 surround sound format. In the space 2 a plurality of loudspeakers of a loudspeaker arrangement 5 are distributed, the lower and higher listening levels 4a, 4b, 5a, 5b are assigned.

In the front area of the room 2 are the upper listening level 4a with two loudspeakers with the left higher signal LHI and the right one higher signal Rm than output signals. Further, in the front area of the room 2, the lower listening level 5a having four loudspeakers with the left signal L, the channel C (center), the right channel R and the channel LFE (Low Frequency Effect) as output signals. In the rear area of the room 2 are the upper listening level 4b with two speakers with the left higher surround signal SL.W and the right higher surround signal Saw as output signals. Furthermore, located in the front area of the room 2, the lower listening level 5b with two speakers with the two surround signals SL, SR as output signals.

Before the signals in the lower and upper listening levels 4a, 4b, 5a, 5b are distributed to the loudspeakers, they have been processed in the context of a multi-channel sound system and on the basis of the input signals R and L by an audio processor provided for this purpose.

Fig. 2 shows the inventive method, starting from the two input channels R and L via linear and parallel channels guided 8.9 the output signals R and L in the lower listening plane 7 and in the upper listening plane 6, the left output signal ü-n and generated right output signal RHI, so that four output signals, two for the upper and two for the lower Hörrebene generated. For the implementation of the method is a signal processor in the form of an audio processor, on which there is a software. The software contains an algorithm which is processed by the signal processor, the algorithm detecting the method.

In the upper listening plane 6, as shown in FIG. 2 further shows, proceeding from the two input signals L and R further process steps.

In detail, the procedural sections are:

a decoding,

a signal control, a phase correction,

a frequency adjustment,

- an encoding,

- a master section.

Three channels are first decoded from the two input signals L and R and formed parallel to the channels 8, 9 which are guided linearly to the output. This produces the upper listening plane 6, while the channels 8, 9 which are guided linearly to the output form the lower listening plane 7.

The decoded channels are the left spatial channel RL = L-R, the right spatial channel RR = R-L and the center channel L + R

The channels RL and RR map the premises and rejections within the input signals L, R, whereas the channel C (center channel) maps the addition of both input channels L, R. This makes it possible to further process the input signals L, R, if it is a mono signal. If a mono signal is present at the input, the channels RL and RR remain silent and the channel C carries on the signal information and thus makes further signal processing possible.

After this encoding step, the channel RR is fed to the signal detector 10. This outputs the control signal "1" when the signal strength of RR drops below the selected threshold level and the control signal "0" when the level of the channel RR exceeds the selected one

Threshold level increases. The threshold level is -20dB and the response time (trigger) is zero seconds.

The control signals of the signal detector 10 are multiplied by the signal multiplier 1 1 with the signal of the center channel. If there is no detected signal in the channel RR, so that no stereo signal in the channels RL and RR above or equal to the signal strength determined by the threshold level is present and the signal detector 10 generates the control signal "1", the channel C is multiplied by "1" and fed to further processing. If a detected signal is present in the channel RR, so that a stereo signal in the channels RL and RR is above or equal to the signal strength determined by the threshold level and the signal detector 10 generates the control signal "0", the channel C is set to "0". multiplied and not released for further processing, since the signal is equal to zero, so that it is unequivocally detected whether a stereo signal is present.

In order to avoid a phase rotation of the channels RL, RR ZU, as Figure 2 further illustrates, in a next step, a phase correction is performed to convert the signal from the channels RL and RR in a phase-pure stereo signal. This is achieved by using a delay 12 in the channel RR. The channel RR is delayed to the channel RL so that the phases of both channels in a non-phase-rotated audio signal in stereo to each other. The delay time is 140 samples with a clock rate of 48khz and 16bit.

In order to enhance the later impression of a reflection for the upper listening plane 6, the C channel is also readjusted in phase by a delay 3, which is applied to the channel CR, after the channel C (L + R) after the Signal multiplier 1 1 has been split into the channels CL and CR and so has been continued in dual-mono channels. The channel C is a pure mono channel and can be converted by the splitting into the two duo mono channels CL and CR and the delay of the channel CR to CL by a delay in a stereo signal with a phase correlation above 0. This creates the auditory impression an increased diffuse of the original signal, which contributes to the impression of the range of increased hearing, as a mono signal, which was recorded with increased installed microphones, depending on the nature of the receiving space and the height of the attached microphones, also not linear, but diffuse and with reflections, images. The frequency adjustment of channel C adjusts its frequency-dependent mapping in the later output signals LHI, RHI of the upper listening level 6, independently of the later frequency adjustment of the output signal. As a result, the sound character of the output signals LHI, RHI can be optimally adjusted to the AV device shown in FIGS. 3 to 8, via which these two channels can be radiated

The encoding as a further method step sums the stereo signal of the channels RL, RR with the stereo signal of the channels CL, CR to the channels Lt, Rt in such a way that the channels RL and CL form the channel Lt and the channels CR and RR form the channel Rt , The summation is accompanied by a level adjustment at the level controls 15, 16, 17, 18, since the levels of the newly formed channels Lt, Rt increase by the described summation of the channels RL, RR with CL, CR. The level adjustment lowers the levels RL, RR, CL, CR accordingly, so that it can not come to override by their summation. Encoding now provides a stereo signal, which can be enhanced by the subsequent master section and also played back by commercially available audio playback components. Alternatively, it is also possible to generate two independent stereo signals by not encoding the channels RL, RR and CL, CR, so that four output signals result in the upper listening level 6.

In order to amplify the auditory impression of a "sound reflection upwards", the signals Lt, Rt are further adjusted as shown in FIG. 2 in the context of the master section to their later use in its frequency responses via the equalizers 19, 20 With the desired emission characteristics, the Lt, Rt signals appear farther from the original sound source, and the effect of the sound emission can be mimicked by a frequency response, the further away it is from the original one Sound source to the top, the more, for example, the upper frequencies can be lowered by a low-pass filter. It is also possible by the frequency adjustment to tune the sound result optimally to the speaker or speakers, which emits the output signals Un, RHI later.

Through the use of a reverb or / and a stereo delay 21, which are added to the signal Lt, Rt in a ratio that is adjusted individually and according to the nature of the method, a spatiality, and a sound delay is shown. This ensures that the output signals LHI, RHI of the upper listening level 6 can also represent different premises and sound delays through the use of different, storable presets in order to be able to adapt the sound result even closer to a true "sound reflection upwards", as well as the individual sound ideas of the manufacturer and / or the users.

To further enhance the sense of hearing that the output signals LHI, RHI reproduce sound "from the bottom up", a compression stage is inserted into the master section as shown in Fig. 2. The adjustment of the compressor 22 or a limiter ensures in that the signal is smoothed such that the sound peaks can be intercepted and the quieter parts of the audio signal Lt.Hi, Rt.Hi can be raised, which enhances the auditory impression of the diffused and distant sound, since sound peaks preferably occur and decrease near a sound source the further the receiving microphone is moved upwardly therefrom, and the compression of the ratio allows the dynamics of the L, R channels in the lower listening plane 7 to be adjusted.

Another method step provides the level adjustment of the channels Lt.Hi, Rt.Hi at the level controls 23, 24 by adjusting the output level in relation to channels of the lower listening plane 7, so that the impression of Listening can be perfectly matched to the respective listening situation. Alternatively, it is also possible to add the audio signal UHI, Rt.Hi back to the channels L, R in order to be able to present an increased sound impression even in loudspeaker systems with only two loudspeakers or even only one.

The following parameters can be considered for the individual process steps:

- Phase correction:

Delay time: 140 samples at 48khz, 16bit clocking

- Phase adjustment C channel:

Delay time: 10 samples at clock rate 48khz, 16bit

Frequency tuning C-channel:

High Pass Filter: Cut-off frequency at 200 Hz, Gain = 0, Q-factor = 1.41 Low Pass Filter: Cut-off frequency at 3000 Hz, Gain = 0, Q-factor = 1 .41

- Encoding:

The levels are adjusted so that the encoded summation of channels RL, RR, CL, CR has the same level (dB) as that of RL. RR before the summation

- Master Section / Frequency Tuning;

HighPass filter: Cutoff frequency at 200 Hz, Gain = 0, Q factor = 1 .41 LowPass filter: Cutoff frequency at 3000 Hz, Gain = 0, Q factor = 1 .41

Master Section / Spatiality / Reflection: Individually adjustable, no ideal settings, depends on the use of the method. Hall decay is short, so swells from 0.51 seconds to 0.67 seconds and a predelay of 20 milliseconds

- Master Section / Compression:

Threshold: -10 dB

Ratio: 8: 00: 1

Attack: 0.46 milliseconds

Release: 560 milliseconds

Knee: 80

- Master Section Level Metering (dB):

The level adjustment is individually adjustable to the device / environment in which the method is to be used

Figures 3 to 8 show audio-video devices (AV devices), in which the inventive method is integrated. For this purpose, the AV devices each have a signal processor, not shown in FIGS. 3 to 8, on which software is located. The software contains an algorithm that is processed by the signal processor in the form of an audio processor, wherein the algorithm detects the inventive method. The AV devices shown in FIGS. 3 to 7 have in common that in addition to audio input and audio output channels, they also have image input and output channels.

AV devices, such as a television set (TV) and a flatscreen 28 shown in FIGS. 3a, 3b do not have, as before, only one or two loudspeakers for emitting monaural or stereo sound, but three loudspeakers 26, 27 for the monoklang (Fig. 3b) and four speakers 26, 27th for the stereo sound (Fig. 3a), since the upper listening plane has been added. The upper listening plane is to a certain extent extracted from the lower listening plane by the encoding described in FIG. 2, which is indicated in FIGS. 3 to 8 by the dashed arrows. The loudspeakers 26, 27 are conventionally installed according to individual equipment requirements and mounted so as to allow a self-tuned listening field. It is also possible, for example, to let the loudspeakers of the upper listening plane radiate upwards in order to make the listening field to become even more diffuse upwards.

Further application examples are a mobile PC 25 (FIGS. 4a, 4b), a tablet PC 29 (FIGS. 5a, 5b) and a smartphone 31 (FIGS. 7a, 7b) both in vertical use and horizontal use, and a radio 32 (FIG. Fig. 8a, 8b).

Also, a sound bar 33 is not, as shown in Fig. 6a, 6b, used only to reproduce the overall sound of an AV device, such as a television, but according to the invention also for the blasting of the extracted upper listening plane. This results in new speaker constellations within these types of devices because z. As well as a sound bar with individual outputs according to the invention for the upper listening level, the otherwise no longer active loudspeakers of the TV set with the new signals of the upper listening level while operating a sound bar and thus can operate the TV more economically. Since a stereo signal is also generated within the scope of the invention, it can in turn be combined in the AV devices with matrix surround decoders in order to also subject the sound of the upper listening plane to a surround decoding. This makes it possible to extract an entire upper listening plane forward and backward.

The present invention is not limited in its execution to the embodiments given above. Rather, a number Variants conceivable, which make use of the solution shown in other types. For example, the channels 8, 9 in the lower listening plane 7 can also be processed further.

The principle according to the invention of the modularly expandable smallest unit of a signal generation, which leads to complex loudspeaker configurations, is also illustrated by FIG. 9.

Starting from the two input channels R and L, the output signals R and L are generated in the lower listening plane 7 and in the upper listening plane 6 the left output signal LHI and the right output signal RHI by means of an algorithm in the signal processor 34, so that initially four output signals, two for the upper listening level 6 and two for the lower listening level 7, are generated.

In the upper listening plane 6, as shown in FIG. 9, the left output signal LHI and the right output signal RH * ZU are then added to a mono signal LHI + RHI and supplied to a first loudspeaker 35.

The output signals R and L in the lower listening plane 7 are routed as channels Li and Ri directly to the speakers 36, 37 of the soundbar 40.

At the same time, the output signals R and L serve as input signals R and L in order to generate a lower hearing level 7 and an upper hearing level 6 again in the context of the method according to the invention, which in turn takes place by means of the algorithm in the signal processor 34 on which the software is located. The software contains an algorithm, which is processed by the signal processor.

In this case, starting from the splitting of the input signals R and L, the output signals R and L in the lower listening plane 7 and in the upper listening plane 6 generates the left output signal LHI and the right output signal RHI, so again four output signals, two for the upper listening level . 6 ie LHI and RHI, and two for the lower listening plane 7, ie L and R, are generated. Thereafter, the signals LHI and RHI are added to the signals R and L in the lower listening plane 7, ie LHI is mixed with the signal L and added with the signal R. The added or mixed signals are thereby supplied to two further speakers 38, 39 of the soundbar 40 in the lower listening level. The soundbar 40 thus has a total of five output channels, namely four output signals R, L, LHI + L, + R in the lower listening level 7 and an output LHI + RH in the upper listening level 6, where all output channels can also be further processed by level control, equalizer, compressor, etc.

The variant of a modularly expandable smallest unit shown in FIG. 9 can be supplemented by a bass box (subwoofer) 41 in a soundbar, as illustrated in FIG. For this purpose, as illustrated in FIG. 10, the output signals R and L in the lower listening plane in the signal sequence before their new splitting are sent through a low-pass filter 42 and simultaneously processed as R and L signals in the signal processor 34.

A further variant of the principle according to the invention of the modularly expandable smallest unit of a signal generation, which leads to complex loudspeaker configurations, is also illustrated in FIG. 11.

Fig. 1 shows the inventive method, the two input channels RH and Lti, which arise from the summations R + C and L + C (C = center channel), the output signals Rm and Lmi in the upper listening plane 7 and in the lower listening plane 6, the left output signal Li and the right output signal Ri are generated to produce four output signals, two for the upper and two for the lower listening plane. Here, too, the signal processor 34 is used for the generation, specifically in the form of an audio processor, on which there is a software containing the algorithm. The embodiment of the method according to the invention shown in FIG. 11 differs from that described in FIG. 10 in that the generated output signals RIHI, Linn, Li and Ri do not serve as input signals again, but in the processor 34 two further input signals S and SL in parallel Shape of surround signals are processed into output signals that are decoded by a parallel processing in the output signals R2H1, L2H1, L.2 and R2 in the upper and lower listening levels. The two output signals Li, L2 and the two output signals R1, R2 are sent to the speakers of the lower listening level 6, whereas the output signals LiHi, RIHI, l_2Hi and R2H1 the upper listening level 7, as further illustrated in Figure 1, to signals RIHI, ÜHI the upper listening level 7 are summed, the speakers of the upper listening level 7 are supplied.

The further channel LFE is led directly to a separate output and fed there as an output channel LFE another speaker, this output channel, as well as all other output channels, also by level control, equalizer, compressor, etc. can be processed. The speaker configuration of an audio device corresponding to the embodiment described in FIG. 11 is illustrated in FIG. 12.

In both embodiments shown in FIGS. 10 and 11, it is common that the method according to the invention is repeatedly executed in the signal processor.

LIST OF REFERENCE NUMBERS

2 room

3 listeners

5 speaker arrangement

4a, 4b, 6 upper listening plane

5a, 5b, 7 lower listening level

8, 9 channels

10 signal detector

1 1 signal multiplier

12,13,21 delay

14,19,20 equalizer

15.16 level control

17,18 level control

22 compressor

23.24 level control

25 pcs

26.27 speakers

28 flat screen

29 pcs

31 smartphone

32 radio

33 soundbar

34 signal processor

35,36,37 speakers

38.39 speakers

0 Soundbar

1 bassbox

2 lowpass filters

Claims

claims:

1 . A method of audio reproduction in a multi-channel sound system with two input signals L and R, in which output signals for different listening levels are generated, characterized in that only a lower listening plane (7) and only one upper listening plane (6) are generated, with a maximum of six output signals with a maximum two output signals for the lower listening level (7) and a maximum of four output signals for the upper listening level (6) are generated.

2. The method according to claim 1, characterized in that for the signals in the lower listening plane (7) and upper listening plane (6) stereo signals are generated.

3. The method according to claim 1, characterized in that for the signals in the lower listening plane (7) and upper listening plane (6) mono signals are generated.

4. The method according to claim 1, characterized in that for the signals in the lower listening plane (7) mono signals are generated.

5. The method according to claim 1, characterized in that for the signals in the upper listening plane (7) mono signals are generated.

6. The method according to any one of claims 1 to 5, characterized in that the output signals serve as further input signals.

7. The method according to any one of claims 1 to 6, characterized in that channels are decoded from the provided for the input signals R and L input channels.

8. The method according to claim 7, characterized in that the decoded channels in the form of a left spatial channel RL = LR, a right Room channel RR = RL and a center channel C = L + R are generated.

9. The method according to any one of claims 7 or 8, characterized in that the decoded channels from the input channels linear and parallel channels (8, 9) are generated.

10. The method according to claim 9, characterized in that R and L are generated as output signals for the lower listening plane (7).

1 1. Method according to one of claims 6 to 10, characterized in that the decoded signals to output signals of the higher listening level

(6) be further processed.

12. The method according to any one of the preceding claims, characterized in that at least a part of the input channels and / or the output channels are added together.

13. The method according to any one of the preceding claims, characterized in that a maximum of two output signals for the lower listening level

(7) and a maximum of two output signals for the upper listening level (6) are generated.

14. Device with audio input and audio output channels and a processor, wherein the device loudspeakers (26, 27, 33) are associated, characterized in that on the processor software is imported, which contains an algorithm that is processed by the processor, wherein the algorithm detects the method according to one of claims 1 to 9.

A device according to claim 14, characterized in that it has image input and image output channels.