Apparatus and method for generating control signals for a loudspeaker system with spectral interlacing in the lower frequency range
An apparatus for generating control signals for a loudspeaker system with two sound generators including a first input for a first channel signal of a multi-channel audio signal; a second input for a second channel signal of the multi-channel audio signal; a first output for a first control signal for a first sound generator; a second output for a second control signal for a second sound generator; a base differential mode signal generator for forming a base differential mode signal from the first channel signal and the second channel signal at the second input; a differential mode signal generator for generating a first differential mode signal and a second differential mode signal from the base differential mode signal, wherein the first differential mode signal is phase-shifted with respect to the second differential mode signal; and a mixer for mixing a common mode signal with the first differential mode signal.
1 . An apparatus for generating control signals for a loudspeaker system with two sound generators, comprising:
a first input configured for a first channel signal of a multi-channel audio signal;
a second input configured for a second channel signal of the multi-channel audio signal;
a first output configured for a first control signal for a first sound generator;
a second output configured for a second control signal for a second sound generator;
a base differential mode signal generator configured for forming a base differential mode signal from the first channel signal and the second channel signal;
a differential mode signal generator configured for generating a first differential mode signal and a second differential mode signal from the base differential mode signal, wherein the first differential mode signal is phase-shifted with respect to the second differential mode signal; and
a mixer configured for mixing a common mode signal with the first differential mode signal so as to acquire the first control signal, and for mixing the common mode signal with the second differential mode signal so as to acquire the second control signal,
wherein the differential mode signal generator comprises:
a frequency filter configured for receiving the base differential mode signal as one input signal or configured for receiving a first phase shifted signal and a second phase shifted signal derived from the base differential mode signal as several input signals and configured for generating one low-pass signal or several low-pass signals from the one input signal or the several input signals received by the frequency filter; and
a spectral interlacer configured for spectrally filtering the one low-pass signal or a first low-pass signal of the several low-pass signals in a first manner so as to acquire a first filtered signal, and configured for spectrally filtering the one low-pass signal or a second low-pass signal of the several low-pass signals in a second manner so as to acquire a second filtered signal that differs from the first filtered signal, and
wherein the differential mode signal generator is configured to use the first filtered signal as the first differential mode signal or to derive the first differential mode signal from the first filtered signal, or wherein the differential mode signal generator is configured to use the second filtered signal as the second differential mode signal or to derive the second differential mode signal from the second filtered signal.
2 . The apparatus according to claim 1 , wherein the loudspeaker system comprises a tweeter, and comprising:
a third output configured for a third control signal for the tweeter; and
a tweeter signal generator configured for generating the third control signal from the first channel signal or the second channel signal.
3 . The apparatus according to claim 2 , wherein the tweeter signal generator comprises a high-pass filter.
4 . The apparatus according to claim 3 , wherein a cutoff frequency of the high-pass filter of the tweeter signal generator is between 3 kHz and 5 kHz.
5 . The apparatus according to claim 2 , provided for a first reproduction position for the first channel signal,
wherein the common mode signal generator is configured to generate the common mode signal by using the first channel signal and without using the second channel signal, and wherein the tweeter signal generator is configured to determine the third control signal by using the first channel signal and without using the second channel signal.
6 . The apparatus according to claim 2 , provided for a second reproduction position for the second channel signal,
wherein the common mode signal generator is configured to generate the common mode signal by using the second channel signal without using the first channel signal, and
wherein the tweeter signal generator is configured to determine the third control signal by using the second channel signal without using the first channel signal.
7 . The apparatus according to claim 2 , configured for a third reproduction position between a first reproduction position for the first channel signal and a second reproduction position for the second channel signal, wherein the common mode signal generator is configured to generate the common mode signal by using a combination of the first channel signal and the second channel signal, and
wherein the tweeter signal generator is configured to determine the third control signal by using a combination of the first channel signal and the second channel signal.
8 . The apparatus according to claim 2 , wherein the tweeter signal generator is configured to generate the third control signal additionally by using a combination with the base differential mode signal.
9 . The apparatus according to claim 1 , comprising:
a common mode signal generator configured for generating the common mode signal from the first channel signal or the second channel signal for the first control signal and the second control signal.
10 . The apparatus according to claim 9 , wherein the common mode signal generator comprises a low-pass filter.
11 . The apparatus according to claim 10 , wherein a cutoff frequency of the low-pass filter is between 3 kHz and 5 KHz.
12 . The apparatus according to claim 1 , comprising:
wherein the frequency filter is configured to generate one or several high-pass signals from the input signal or the several input signals in received by the frequency filter, and
wherein the differential mode signal generator is configured to derive the first differential mode signal from the first filtered signal by using the one high-pass signal or a first high-pass signal of the several high-pass signals, and to derive the second differential mode signal from the second filtered signal by using the one high-pass signal or a second high-pass signal of the several high-pass signals.
13 . The apparatus according to claim 1 , wherein the differential mode signal generator is configured to generate the first differential mode signal and the second differential mode signal with a phase shift that is between 100° and 260°, wherein the first differential mode signal comprises a phase shift of between +45° and +135° with respect to the base differential mode signal, and wherein the second differential mode signal comprises a phase shift of between −45° and −135° with respect to the base differential mode signal.
14 . The apparatus according to claim 1 , wherein the differential mode signal generator comprises:
a phase shifter configured for phase shifting the base differential mode signal by a first phase value so as to acquire the first phase-shifted signal, and by a second phase value so as to acquire the second phase-shifted signal, wherein the second phase value differs from the first phase value;
the frequency filter configured for generating the first low-pass signal from the first phase-shifted signal and configured for generating the second low-pass signal from the second phase-shifted signal;
wherein the spectral interlacer is configured for spectrally filtering the first low-pass signal and for spectrally filtering the second low-pass signal, and
wherein the mixer is configured to determine the first control signal from the first filtered signal and the common mode signal, and wherein the mixer is configured to determine the second control signal from the second filtered signal and the common mode signal.
15 . The apparatus according to claim 14 , wherein the frequency filter is configured for generating the first low-pass signal and a first high-pass signal from the first phase-shifted signal and for generating the second low-pass signal and a second high-pass signal from the second phase-shifted signal, and
wherein the mixer is configured to determine the first control signal from the first high-pass signal, the first filtered signal, and the common mode signal, and wherein the mixer is configured to determine the second control signal from the second high-pass signal, the second filtered signal, and the common mode signal.
16 . The apparatus according to claim 1 ,
wherein the frequency filter is configured for generating the one low-pass signal from the base differential mode signal;
wherein the spectral interlacer is configured for spectrally filtering the one low-pass signal in a first manner so as to acquire the first filtered signal, and for spectrally filtering the one low-pass signal in a second manner so as to acquire the second filtered signal; and
wherein the differential mode signal generator comprises:
a phase shifter configured for phase shifting the first filtered signal or a signal derived from the first filtered signal by a first phase value so as to acquire the first differential mode signal, and configured for phase shifting the second filtered signal or a signal derived from the second filtered signal by a second phase value so as to acquire the second differential mode signal, wherein the second phase value differs from the first phase value.
17 . The apparatus according to claim 16 ,
wherein the frequency filter is configured for generating the one high-pass signal and a low-pass signal from the base differential mode signal; and
wherein the differential mode signal generator comprises:
a combiner configured for combining the first filtered signal with the first high-pass signal so as to acquire a first combination signal, and configured for combining the second filtered signal with the first high-pass signal so as to acquire a second combination signal, wherein the first combination signal is the signal derived from the first filtered signal, and wherein the second combination signal is the signal derived from the second filtered signal; and
wherein the phase shifter is configured for phase shifting the first combination signal by the first phase value so as to acquire the first differential mode signal, and wherein the phase shifter is configured for phase shifting the second combination signal by the second phase value so as to acquire the second differential mode signal.
18 . The apparatus according to claim 1 , wherein the spectral interlacer is configured to, when processing in the first manner, use one first or several first bandpass filters and, when processing in the second manner, use one or several second bandpass filters, wherein the one first or the several first bandpass filters and the one or the several second bandpass filters are configured such that the one first or the several first bandpass filters have a passthrough range in a frequency range, and the second or the several second bandpass filters have a blocking range or several blocking ranges in the frequency range.
19 . The apparatus according to claim 1 , wherein the spectral interlacer comprises a first low-pass filter configured for filtering an input signal of the spectral interlacer in the first manner, and a second high-pass filter or bandpass filter configured for filtering the input signal of the spectral interlacer in the second manner, wherein a blocking range of the first low-pass filter overlaps a passthrough range of the second high-pass filter or bandpass filter with respect to a frequency.
20 . The apparatus according to claim 19 , wherein the spectral interlacer comprises a third bandpass filter configured for filtering in the first manner, and comprises the first bandpass filter configured for filtering the input signal in the first manner, wherein a passthrough range of the third high-pass filter or the bandpass filter overlaps with a blocking range of the first bandpass filter.
21 . The apparatus according to claim 20 , wherein the spectral interlacer comprises a third bandpass filter configured for filtering in the first manner, and comprises a fourth high-pass filter configured for a fourth bandpass filter configured for filtering in the second manner, wherein a pass through range of the fourth bandpass filter overlaps with a blocking range of the third bandpass filter.
22 . The apparatus according to claim 1 , wherein the frequency filter comprises a high-pass filter and a low-pass filter.
23 . The apparatus according to claim 22 , wherein a cutoff frequency of the high-pass filter is between 150 Hz and 500 Hz, or a cutoff frequency of the low-pass filter is between 150 Hz and 500 Hz.
24 . The apparatus according to claim 1 , wherein the base differential mode signal generator comprises:
a controllable amplifier configured for amplifying or attenuating a raw signal determined from the first channel signal and the second channel signal, according to an adjustment value, so as to acquire the base differential mode signal; and
a controller configured for controlling the controllable amplifier on the basis of the first channel signal and the second channel signal, on the basis of the raw signal, or on the basis of metadata.
25 . The apparatus according to claim 1 , wherein the base differential mode signal generator comprises:
an inverter configured for inverting the first channel signal or the second channel signals;
an adder configured for adding an inverted channel signal to another channel signal so as to acquire the base differential mode signal or a raw differential mode signal.
26 . The apparatus according to claim 1 , wherein the base differential mode signal generator is configured to calculate a difference from the first channel signal and the second channel signal or between the second channel signal and the first channel signal so as to acquire the base differential mode signal, or to calculate a raw signal from which the base differential mode signal is to be derived.
27 . The apparatus according to claim 1 , wherein the base differential mode signal generator is configured to combine the first channel signal and the second channel signal to the extent that there is a phase difference between 45° and 135° between the first channel signal and the second channel signal.
28 . The apparatus according to claim 1 , wherein the base differential mode signal generator is configured
for shifting a phase of the first channel signal or the second channel signal by a phase value of between 60° and 300°, and
for adding or for subtracting a result of shifting the phase so as to acquire the base differential mode signal.
29 . A method for generating control signals to a loudspeaker system with two sound generators, comprising:
receiving a first channel signal of a multi-channel audio signal and a second channel signal of the multi-channel audio signal;
outputting a first control signal for a first sound generator of the two sound generators, and a second control signal for a second sound generator of the two sound generators;
forming—a base differential mode signal from the first channel signal and the second channel signal;
generating a first differential mode signal and a second differential mode signal from the base differential mode signal, wherein the first differential mode signal is phase-shifted with respect to the second differential mode signal; and
mixing a common mode signal with the first differential mode signal so as to acquire the first control signal, and mixing the common mode signal with the second differential mode signal so as to acquire the second control signal,
wherein the generating comprises:
receiving, by a frequency filter, the base differential mode signal as one input signal or receiving, by a frequency filter, a first phase shifted signal and a second phase shifted signal derived from the base differential mode signal as several input signals and generating one or several low-pass signals from the one input signal or the several input signals received by the frequency filter; and
spectrally filtering the one low-pass signal or a first low-pass signal of the several low-pass signals in a first manner so as to acquire a first filtered signal, and spectrally filtering the one low-pass signal or a second low-pass signal of the several low-pass signals in a second manner so as to acquire the second filtered signal that differs from the first filtered signal,
wherein the first filtered signal is used as the first differential mode signal or the first differential mode signal is derived from the first filtered signal, and wherein the second filtered signal is used as the second differential mode signal or the second differential mode signal is derived from the second filtered signal.
30 . The method according to claim 29 , wherein the generating comprises generating one or several high-pass signals from the input signal or the several input signals received by the frequency filter, and
wherein the generating the first differential mode signal and the second differential mode signal comprises generating the first differential mode signal by using the one high-pass signal or a first high-pass signal of the several high-pass signals, and generating the second differential mode signal by using the one high-pass signal or a second high-pass signal of the several high-pass signals.
31 . The method according to claim 29 , wherein the generating comprises:
phase shifting the base differential mode signal by a first phase value so as to acquire the first phase-shifted signal, and phase shifting the base differential mode signal by a second phase value so as to acquire the second phase shifted signal, wherein the second phase value differs from the first phase value;
generating the first low-pass signal from the first phase-shifted signal, and generating the second low-pass signal from the second phase-shifted signal;
wherein the first low-pass signal and the second low-pass signal are spectrally filtered, and wherein the mixing comprises determining the first control signal from the first filtered signal and the common mode signal, and determining the second control signal from the second filtered signal and the common mode signal.
32 . The method according to claim 31 ,
wherein the generating comprises generating the first low-pass signal and a first high-pass signal from the first phase-shifted signal, and generating the second low-pass signal and a second high-pass signal from the second phase-shifted signal, and
wherein the mixing comprises determining the first control signal from the first high-pass signal, the first filtered signal, and a common mode signal, and determining the second control signal from the second high-pass signal, the second filtered signal, and the second common mode signal.
33 . The method according to claim 29 , comprising:
generating the one low-pass signal from the base differential mode signal;
wherein the spectrally filtering comprises spectrally filtering the one low-pass signal in a first manner so as to acquire the first filtered signal, and spectrally filtering the one low-pass signal in a second manner so as to acquire the second filtered signal; and
wherein the generating comprises:
phase shifting the first filtered signal or a signal derived from the first filtered signal by a first phase value so as to acquire the first differential mode signal, and
phase shifting the second filtered signal or a signal derived from the second filtered signal by a second phase value so as to acquire the second differential mode signal, wherein the second phase value differs from the first phase value.
34 . The method according to claim 33 , comprising:
generating a high-pass signal and a low-pass signal from the base differential mode signal; and
combining the first filtered signal with the high-pass signal so as to acquire a first combination signal, and combining the second filtered signal with the high-pass signal so as to acquire a second combination signal, wherein the first combination signal is the signal derived from the first filtered signal, and wherein the second combination signal is the signal derived from the second filtered signal; and
phase shifting the first combination signal by the first phase value so as to acquire the first differential mode signal, and phase shifting the second combination signal by the second phase value so as to acquire the second differential mode signal.
35 . A non-transitory storage medium having stored thereon a computer program for performing the method according to claim 29 , when the computer program is run on a computer or a processor.