Patent Application
20240422493
Typically, acoustic scenes are recorded using a set of microphones. Each microphone outputs a microphone signal. For example, 25 microphones may be used for an audio scene of an orchestra. A sound engineer then mixes the 25 microphone output signals, e.g., into a standard format such as a stereo format, a 5.1 format, a 7.1 format, a 7.2 format, or any other corresponding format. In case of a stereo format, e.g., the sound engineer or an automatic mixing process generates two stereo channels. In the case of a 5.1 format, mixing results in five channels and one subwoofer channel. Analogously, in case of a 7.2 format, e.g., mixing results in seven channels and two subwoofer channels. If the audio scene is to be rendered in a reproduction environment, a mixing result is applied to electrodynamic loudspeakers. In a stereo reproduction scenario, there are two loudspeakers, the first loudspeaker receiving the first stereo channel, and the second loudspeaker receiving the second stereo channel. For example, in a 7.2 reproduction format, there are seven loudspeakers at predetermined positions, and two subwoofers, which can be placed relatively arbitrarily. The seven channels are applied to the corresponding loudspeakers, and the subwoofer channels are applied to the corresponding subwoofers.
The use of a single microphone arrangement when capturing audio signals, and the use of a single loudspeaker arrangement when reproducing the audio signals typically neglects the true nature of the sound sources. European patent EP 2692154 B1 describes a set for capturing and reproducing an audio scene, in which not only the translation but also the rotation and, in addition, the vibration is captured and reproduced. Thus, a sound scene is not only reproduced by a single capturing signal or a single mixed signal but by two capturing signals or two mixed signals that, on the one hand, are recorded simultaneously, and that, on the other hand, are reproduced simultaneously. This ensures that different emission characteristics of the audio scene are recorded compared to a standard recording, and are reproduced in a reproduction environment.
To this end, as is illustrated in the European patent, a set of microphones is placed between the acoustic scene and a (imaginary) listener space to capture the “conventional” or translation signal that is characterized by a high directionality, or high quality.
In addition, a second set of microphones is placed above or to the side of the acoustic scene to record a signal with lower quality, or lower directionality, that is intended to represent the rotation of the sound sources in contrast to the translation.
On the reproduction side, corresponding loudspeakers are placed at the typical standard positions, each of which has a omnidirectional arrangement to reproduce the rotation signal, and a directional arrangement to reproduce the “conventional” translatory sound signal. In addition, there is a subwoofer at each of the standard positions, or there is only a single subwoofer at an arbitrary location.
European patent EP 2692144 B1 discloses a loudspeaker for reproducing, on the one hand, the translatory audio signal and, on the other hand, the rotatory audio signal. Thus, the loudspeaker has, on the one hand, an arrangement that emits in an omnidirectional manner, and, on the other hand, an arrangement that emits in a directional manner.
European patent EP 2692151 B1 discloses an electret microphone that can be used for recording the omnidirectional or the directional signal.
European patent EP 3061262 B1 discloses earphones and a method for manufacturing earphones that generate both a translatory sound field and a rotatory sound field.
European patent application EP 3061266 A0, which is intended for grant, discloses earphones and a method for producing earphones configured to generate the “conventional” translatory sound signal by using a first transducer, and to generate the rotatory sound field by using a second transducer arranged perpendicular to the first transducer.
Recording and reproducing the rotatory sound field in addition to the translatory sound field leads to a significantly improved and therefore high-quality audio signal perception that almost conveys the impression of a live concert, even though the audio signal is reproduced by the loudspeaker or headphones or earphones.
This achieves a sound experience that can almost not be distinguished from the original sound scene in which the sound is not emitted by loudspeakers but by musical instruments or human voices. This is achieved by considering that the sound is emitted not only in a translatory manner but also in a rotary manner and possibly also in a vibrational manner, and is therefore to be recorded and reproduced accordingly.
There are several possibilities to synthetically generate, from already existing audio pieces in which only the translatory sound field has been recorded, a representation of the audio piece comprising both translatory components and rotatory components. Such methods are in WO2022218822A1 or in exemplarily disclosed in WO2022157251A2, WO2022253768A1.
To generated synthetic signals, stereo properties of existing audio pieces are used, and the difference between the left and the right stereo channel is used to synthetically reconstruct a rotation of the sound field.
However, this approach is limited to stereo signals and does not enable “reconstructing,” so to speak, a rotatory sound field for mono signals, for example.
In addition, the synthetic method is limited to the effect that it cannot be used for formats of higher order, i.e. formats comprising more than two channels (left and right) or more than three channels (left, middle, right) if high quality results are to be achieved.
In addition, it has been found that, even for a synthetic recovery of rotation information from stereo signals recorded in a translatory way, there are quality problems that, e.g., result from the fact that the differential signal of a stereo signal has strong power deviations that cause problems with respect to the synthetically generated rotation signal. Overall, thus, the synthetic generation of “enriched” audio pieces, i.e. audio pieces not only comprising translatory components but also describing the rotatory sound field and ultimately being able to generate the same by means of appropriate reproduction systems, provide a good possibility to improve existing audio content that is purely translatory. However, the qualities ultimately achievable for the full sound field with translatory sound on the one hand and rotatory sound on the other hand are limited in the synthetic generation.
According to an embodiment, an apparatus for re-recording an existing audio piece with a first number of channels may have: a loudspeaker arrangement for reproducing the first number of channels with a first number of loudspeaker systems in a reproduction space, wherein the first number is 1 or larger than 1, and wherein the one loudspeaker system or the loudspeaker systems of the first number of loudspeaker systems is/are configured to generate, for each channel of the first number of channels, a translation sound field and a rotation sound field in the reproduction space; a microphone arrangement with a second number of microphone systems arranged at different microphone positions in the reproduction space, wherein each microphone system of the second number of microphone systems is configured to capture a pressure signal and additionally a directional differential signal; and an interface for outputting or recording the pressure signal and the directional differential signal or a differential signal derived from the directional differential signal as a re-recorded audio piece.
According to another embodiment, a method for re-recording an existing audio piece with a first number of channels may have the steps of: reproducing the first number of channels with a first number of loudspeaker systems in a reproduction space, wherein the first number is 1 or larger than 1, or wherein the one loudspeaker system or the loudspeaker systems of the first number of loudspeaker systems is/are configured to generate, for each channel of the first number of channels, a translation sound field and a rotation sound field in the reproduction space; recording with a second number of microphone systems arranged at different microphone positions in the reproduction space, wherein each microphone system of the second number of microphone systems is configured to capture a pressure signal and additionally a directional differential signal; and outputting or recording the pressure signal and the directional differential signal or a differential signal derived from the directional differential signal as a re-recorded audio piece.
According to another embodiment, a re-recorded audio piece may have: a first pressure signal, a first directional differential signal, and a second directional differential signal for a first channel; and a second pressure signal, a third directional differential signal, and a fourth directional differential signal for a second channel.
The present invention is based on the finding that the reamping method is used for generating a high quality audio representation. In the reamping method or in re-recording an existing audio piece with one or several channels, i.e. a first number of channels, the audio piece is reproduced, i.e. with loudspeakers arranged at certain loudspeaker positions. If the existing audio piece only has a single mono channel, the loudspeaker for re-recording is arranged in the middle with respect to a listener position in a reproduction space (or reproduction room). If the existing audio piece has two channels, i.e. a left channel and a right channel, two different loudspeaker systems are arranged at the two positions on the left and the right. Analogously hereto, if the audio piece has three channels, i.e. a left channel, a middle channel, and a right channel, three loudspeaker systems are arranged at the positions left, middle, right in the reproduction space. However, as is the case in conventional reamping, the loudspeaker systems are not simple translatory loudspeakers, but they are loudspeaker systems that are able to generate a translation sound field and a rotation sound field in the reproduction space. To this end, the loudspeaker systems according to the invention are controlled (driven) with two different audio signals, i.e. one audio signal for the sound transducer system for generating the translation sound field and a further audio signal for the sound transducer system for the rotation sound field. According to the invention, both audio signals are generated by one and the same channel of the existing audio piece.
In order to obtain the re-recorded audio piece, according to the invention, individual microphone systems are arranged at the reproduction positions desired for a format of higher order, wherein said individual microphone systems are configured to capture an omnidirectional pressure signal and at least one directional differential signal for the position at which the respective microphone systems are arranged. The omnidirectional pressure signal represents the sound pressure and represents a typical mono signal or a typical one-channel signal of a multi-channel recording. In addition, the directional differential signal represents a component of the sound velocity at the microphone position. According to the invention, the sound velocity may be captured through different directional differential signals, wherein it is advantageous for a high-quality recording to separately record all three components of the sound velocity, i.e. the directional differential signal in the x direction and the directional differential signal in the y direction and the directional differential signal in the z direction.
The result is output or recorded by means of an interface so that a re-recorded audio piece is obtained that now has a number of channels equal to the number of microphone systems used, wherein each channel now no longer comprises an individual mono signal, as is the case in the existing audio piece, but, beside an omnidirectional audio signal, also one or several directional differential signals to describe the sound velocity at this position either approximately (in the case of only one directional differential signal or a summed-up differential signal) or particularly precisely in the case of three directional differential signals.
The method according to the invention and the corresponding apparatus for re-recording are characterized in that any formats for the audio pieces may be generated, wherein, according to the embodiment, additional microphone systems may be arranged accordingly at corresponding additional positions in the reproduction space.
A reproduction space comprising specific acoustics is used, which, in particular, if this information is still available, is either the same reproduction space in which the existing audio piece has been recorded, or which has similar acoustic properties or at least comparable acoustic properties as the reproduction space in which the existing audio piece has been recorded. This makes it possible to give new “life” to old recordings that are only available in mono or stereo, since, by means of the inventive loudspeaker systems, it is not just the translatory sound field that is generated in the reproduction space but also the rotatory sound field approximated with respect to the rotatory sound field that the artist also generated in the first recording of the existing audio piece in the reproduction space, however, that had not been recorded.
According to the invention, this “omission” in the past may be rectified even if the artist or the group of artists is no longer available.
Thus, it is possible to convert existing recordings that have been recorded without rotatory sound field components into a new particularly high quality format, wherein the special format is achievable by arranging corresponding microphone systems at corresponding positions needed by the special format.
In the case of re-recording a mono piece, two microphone systems for a stereo representation may be achieved, or, e.g., five microphone systems for a surround representation, or significantly higher order formats, e.g., a multichannel arrangement with 22 channels (or any subgroup thereof with less than 22 channels) according to ITU-R BS.2159-9 in a top layer, a middle layer, and a bottom layer, or any other selected arrangement of the different 25 loudspeakers according to ISO/IEC 23003:1. A further format is the Dolby Atmos format with seven loudspeakers in the middle layer and four or also six loudspeakers in the top layer. All of this may simply be achieved by not arranging reproduction loudspeakers in the corresponding reproduction positions of these formats, but by arranging microphone systems so as to respectively record signals at these positions, wherein said signals, when the re-recorded audio piece is to be reproduced at any point in time, represent the corresponding signals at the corresponding reproduction positions, and may be reproduced there by appropriate loudspeakers. However, this reproduction will not be carried out with simple translatory loudspeaker systems but with loudspeaker systems capable of generating a translatory sound field and a rotatory sound field, i.e. which are able to not only generate common mode signals but also differential mode signals.
Embodiments of the present invention will be detailed subsequently referring to the appended drawings, in which:
Each loudspeaker system is configured to generate a translation sound field and a rotation sound field for each channel 111, 112 of the first number of channels. To this end, each loudspeaker system includes two different sound transducer systems, i.e. one sound transducer system for generating the rotation sound field and a separate sound transducer system for generating the translation sound field. To this end, a signal processing element 100 is provided so as to generate two audio signals from each channel. The signal processing element 100 generates from the first channel 111 the first audio signal 111a for the translatory sound transducer system and the second audio signal 111b for the rotatory sound transducer system. Accordingly, the signal processing element 100 also generates from the second channel 112 a first audio signal 112a and a second audio signal 112b, wherein these audio signals are then supplied to the respectively different sound transducer systems of the second loudspeaker system.
Even though embodiments for the loudspeaker systems that will be described in more detail on the basis of
However, the use of separate systems makes it possible that the rotation sound field may be emitted almost omnidirectionally so that a particularly good omnidirectional, that is undirected, excitation of the rotation field may take place in the reproduction space even if the audio piece comprises only a single mono channel or is only a stereo signal with two stereo channels or is a 3-channel format.
Thus, the first number of channels may be one if the existing audio piece has only a single mono channel or when only a single channel is to be used for reamping. Alternatively, the existing audio piece may also have two or more channels so that the first number of channels may also be larger than 1.
Furthermore, the apparatus for re-recording also includes a microphone arrangement with a second number of microphone systems 221, 222, 223, 224, 225 arranged at different positions in the reproduction space. In particular, each microphone system of the second number of microphone systems is configured to capture both an omnidirectional pressure signal and a directional differential signal. The omnidirectional signal is indicated in
In addition, the loudspeaker arrangement includes an interface 150 for outputting or recording the omnidirectional pressure signal and at least one directional differential signal for each of the microphone systems of the number of the second number of microphone systems so as to obtain the re-recorded audio piece 240 either in a recorded form or in an output form. In the embodiment shown in
Alternatively, the omnidirectional signal may also be generated by adding the first channel and the second channel, for example, and it may therefore be introduced separately, as is shown at 151. If neither the omnidirectional signal OD2 nor the directional differential signal D2 is needed by the microphone system 221 at the middle positon, the setup of a microphone system at this location may also be completely omitted so as to reduce the effort for reamping, or for re-recording. Then, the middle channel from the existing audio piece, if available, is added to the re-recorded audio piece or, if not available, is generated from the available left and right channels by means of downmixing, and the result of the downmixing is added to the re-recorded audio piece.
As will be illustrated with reference to
In principle, the reproduction space 110 may be any reproduction space, it does not necessarily have to be an enclosed space, but it simply has a defined spatial extension in which the loudspeaker systems and the microphone systems may be set up at certain positions. Thus, the space may also be a “free space” if the audio piece was a live concert, for example, i.e. it had not been recorded in a specific studio.
However, if the audio piece had been recorded in a studio, it is advantageous to use exactly the same studio as a reproduction space for re-recording again, since the rotation sound field that has been generated but not recorded in the first recording of the audio piece by the artist will now be recorded in addition, so to speak, by the inventive approach for re-recording and will be made available for a high quality audio reproduction.
For comparison,
Depending on the embodiment, a maximum, i.e. a maximum precise, representation of the sound velocity may be recorded explicitly by all three components x, y, z. However, certain “intermediate” representation may be used to reduce the transfer effort, or the size of the re-recorded audio piece. For example, only a single differential signal may be recorded and transferred, e.g. the largest of the three differential signals. Alternatively, the three differential signals may be added to generate and transfer an overall differential signal, e.g. by addition of D1a, D1b, and D1c. Alternatively, two differential signals, i.e. x, y or x, z, or y, z, may be added. Furthermore, any combinations are possible, e.g. only the transfer of the largest differential signal with respect to its power, e.g. in a frame, or in a certain time range, and optionally additionally the second largest signal or a sum of the two remaining directional components, etc. In any case, in contrast to the original audio piece, the re-recorded audio piece will have more “channels,” and each channel will, beside the omnidirectional pressure signal, include at least one directional differential signal being a differential signal that was actually measured, or a signal resulting from the combination, such as an addition, of measured differential signals. In any case, this differential signal will describe the sound velocity more or less precisely, and will enable, if the re-recorded audio piece is to be reproduced, controlling a corresponding differential mode transducer, i.e. a corresponding transducer for the generation of a rotation sound field. As described, the pressure signal is omnidirectional, however, depending on the microphone; it may also carry residuals of a directionality. However, it is a pressure signal, and, in contrast to the directional differential signals representing the sound velocity, it does not represent a direction of a vector field, but does only represent the omnidirectional pressure at the microphone position. It may be obtained in different ways, e.g. through addition of signals of microphone diaphragms, through its own pressure transducer, or through the addition of the two components of the diaphragms of a partial microphone, such as the partial microphone for the z direction.
The inventive concept is useful for an “up-scaling” to take place, i.e. for the second number of microphone systems being larger than the first number of channels. However, in principle, it is also possible to use, e.g., only one channel of an existing audio piece, and to control an inventive loudspeaker system with this channel, with an inventive microphone arranged at the middle positon next to the loudspeaker system or between the listener position 114 and the loudspeaker system, to obtain the re-recorded mono signal now including a directional differential signal in addition to an omnidirectional pressure signal. Thus, the second number may also be equal to the first number.
Further formats are the generation of a re-recorded audio piece with a stereo characteristic from an original audio piece with a mono characteristic or from an original stereo audio piece that did not have any rotation information. In addition, it is also possible to record an enriched, i.e. re-recorded, audio piece with three microphone systems from three original channels, said audio piece now again having three “channels”, wherein each channel now includes a directional differential signal or several directional differential signals in addition to a (omnidirectional) pressure signal.
In particular, it shows a format comprising six reproduction positions and therefore positions for the inventive microphone systems, i.e. the positions 222, 223, 224, 225, 226, 227 in the middle layer. In addition, six further reproduction positions and therefore microphone system positions 226, 227, 228, 229, 230, 231 are shown in the top layer. The resulting re-recorded signal then has the enriched “channels” for the microphone positions 222 to 231 and additionally it has the middle signal that, however, is extracted directly from the existing audio piece and is added to the signal, as is shown at 151 in
The following terms can be seen in
Here, the following terms can be seen: center, low frequency enhancement, surround, direct, side, vertical, height.
A further reproduction format, the 22.2 multichannel, as shown in
According to the invention, microphone systems may be positioned at all reproduction positions shown in
Each audio signal is amplified by a respective amplifier 201c, 201d, 203c, 203d, 202c, 202d. Typically, the loudspeaker systems are active loudspeaker systems so that the amplifier is housed in the loudspeaker systems, as is illustrated in
Only attenuation members 113c and 113d are used to generate the two audio signals 113a, 113b. The channel signal of the existing audio piece for the middle, i.e. track B, or the mono channel 113, is supplied to a branching point 113e, and is supplied from there, via a first attenuation member 113c, to the sound transducer system for generating the rotatory sound 203b, while the second audio signal 113 is generated such that the original signal 113 is attenuated by the second attenuation member 113d. The attenuation members 113c, 113d are adjusted differently to the extent that the attenuation member 113d attenuates less than the attenuation member 113c. By adjusting these adjustable attenuation members, it is possible to adjust the percentage of the rotatory sound for the middle channel. Even if there is just a single mono signal, the emission of the audio signal 113b, even though the signal is in-phase with respect to the audio signal 113a, leads to the fact that a rotation sound field is excited in the reproduction space due to the second sound transducer system 203b. This effect, which is also referred to as “generator effect,” leads to the fact that a rotation sound field is excited in the reproduction space even if the originally existing audio piece did not even have a stereo signal and synthetic generation of a differential mode signal is therefore not possible, which needs the presence of stereo signals. The rotation sound field generated by the transducer 203b leads to the fact that a rotation sound field is propagated, or is excited, in the reproduction space, said rotation sound field being recorded at the microphone positions with respect to a complete representation of the sound velocity, if needed, in the x, y and z directions. Thus, due to a closed reproduction space, significantly better representation may be obtained already in the inventive novel reamping of a mono signal.
The generation of the control signals 111a and 112a for the sound transducer system for reproducing the translation of sound fields takes place both, for the left channel and for the right channel by supplying the left stereo channel, or the right stereo channel, respectively, directly or after attenuation by means of an adaptable attenuation member 1105, or 1205, to the corresponding power amplifier 201d, 202d.
However, to generate the differential signal, i.e. the control signal 111b, 112b, the input-side left stereo channel 111 or 1001, and the right stereo channel 112 or 1002 are used. Thus, two polarity reversals are carried out in blocks 1015, 1016 to then add the result of the polarity reversal in the respective blocks 1013, 1014 to obtain the differential mode signals 1011 or 1012 that, depending on the embodiment, are then supplied directly or after amplification by means of a voltage-controlled amplifier (VCA) 1031, 1032 to the second sound transducer system for generating the rotation sound field. On its way to the loudspeaker, an attenuation in an attenuation member 1101 or 1201 may be carried out. In addition, depending on the implementation, a common mode signal attenuated by an attenuation member 1103 or 1203 may be added to the differential signal at the output of the amplifier 1031 or 1032, or in the output of the adder 1013, 1014, wherein the signal may be attenuated by means of an optional attenuation member 1104, 1204 at the output of the adder 1102 or 1202 carrying out the addition, so as to ultimately obtain the respective second audio signal for the DM transducer system indicated with 111b or 112b.
It is to be noted that all elements 1101, 1102, 1103, 1104, 1105, or 1201, 1202, 1203, 1204, 1205, respectively, are optional elements that, depending on the implementation, may be adjusted firmly to a specific attenuation value that differs from element to element. Alternatively, some or all elements do not have to be present, or an attenuation of 0 may be adjusted. It is also possible that only subgroups of these elements are present.
In addition, the use of the amplifier 1301 or 1302 controlled by the control signal 1035 via the branching point 1033 is optional, which is also illustrated for the optional switch that either supplies the signal 1011 or the signal 1036, or the signal 1012 or the signal 1037, respectively, to the second sound transducer system, or the DM transducer system, 201b, 202b after optional processing.
It is merely advantageous that the second audio signal, i.e. the control signals for the sound transducer system for generating the rotation sound field, is respectively derived from the differences of the two stereo channels available from the originally existing audio piece. In addition, the use of a polarity inverter 1015, 1016 and a subsequent addition at 1013, 1014 is just optional. There may also be a subtraction or an approximate subtraction to the effect that the signal at the output of the operation, i.e. the signal referred to with “A-C” or “C-A”, is based on the difference between the left stereo channel and the right stereo channel without this difference being the exact result of an exact subtraction.
The optional use of a voltage-controlled amplifier 1031 or 1032, or the control of such an amplifier on the basis of a correlation of the left and right channel in general, is described with reference to
The controller 1020 is configured to determine the adjustment value 1035 such that a first adjustment value is determined in case of a first similarity between the first channel signal and the second channel signal, and such that a second adjustment value is determined in case of a second similarity between the first channel signal and the second channel signal, wherein, in particular, the first similarity represents a lower similarity than the second similarity, and wherein the first adjustment value represents a lower amplification than the second adjustment value or a greater attenuation than the second adjustment value. This relationship is schematically illustrated in the mapping function 1000, illustrating an adjustment value for an amplification (adjustment value larger than 1) and/or for an attenuation (adjustment value smaller than 1), namely depending on a similarity scale. In particular, the amplification becomes larger and larger for greater similarity values, i.e. for stronger similarities between the first channel signal and the second channel signal. This is advantageous in that the level loss of the differential mode signal generated as a differential signal or approximate differential signal is leveled out, or partially compensated, through this. On the other hand, the more dissimilar the two channel signals are, the smaller and smaller the amplification becomes, since the level of the differential mode signal increases more and more. In particular, a special situation arises if the first channel signal and the second channel signal are particularly dissimilar, i.e. fully correlated, but inversely phased. Then, the calculation of the differential mode signal leads to an exaggeration of the level of the differential mode signal, which, according to the mapping function to map similarity values to adjustment values, as is schematically shown at 1000 in
An amplification may be an amplification that leads to an increase of the level, i.e. an amplification with an amplification factor larger than 1, or a positive amplification factor on a dB scale. However, an amplification may also be an amplification with an amplification factor of less than 1, i.e. an attenuation. Then, the amplification factor is between 0.1, or in the negative range on a dB scale.
Depending on the embodiment, direct analysis of the signals to determine the adjustment value takes place in the apparatus of
The controller 1020 is configured to determine a correlation value between the first channel signal 1001 and the second channel signal 1002, wherein the correlation value is a measurement for the similarity. The controller 1020 is configured to calculate a normalized cross-correlation function from the first channel signal and the second channel signal, wherein a value of the normalized cross-correlation function is a measurement for the similarity. In particular, the controller 1020 is configured to calculate a correlation value by using a correlation function having a value range of negative and positive values, wherein the controller is configured to determine, for a negative value of the cross-correlation function, an adjustment value that represents an attenuation or amplification, and, for a positive value of the correlation function, the adjustment value that represents an amplification, or attenuation, i.e. the opposite. A typical normalized cross-correlation function has a value range of between −1 and +1, wherein the value −1 means that the two signals are fully correlated but inversely phased, and therefore dissimilar to the maximum.
On the other hand, a value of +1 is obtained if the two channel signals are fully correlated and in-phase, i.e. fully similar. The differential mode signal increases more and more with a decreasing value of −1 to 0 in case of a normalized cross-correlation function, which is why the amplification factor in this range is reduced more and more. With a value of the normalized cross-correlation function between 0 and −1, the similarity decreases more and more, which is why the differential mode signal is attenuated more and more, or is amplified less and less, to counteract the exaggeration of the differential mode signal. A similarity between the channel signals is therefore synchronous with the cross-correlation function only if the two channel signals are in phase, i.e. if the sign of the cross-correlation function is +1. However, the similarity is non-synchronous with respect to the value of the cross-correlation function if the sign of the cross-correlation function is negative.
A mapping function that may be used as a mapping function in 1000 of
In this case, the amplification is either left on a maximum level, or the amplification is lowered to 0 in order to “turn off,” so to speak, the differential mode signal for such a case. Another possibility is to decrease the amplification factor in advance, as is shown by the curved dashed line that then reaches the vertical dashed line, to go into a certain compression at values of maybe 0.6 or 0.7, to go into an amplification of 0 dB at a value of 0.8 or at values of larger than 0.8 but smaller than 1.
In an alternative embodiment of the present invention, the adjustment value is not determined on the basis of the channel signals 1001, 1002, but on the basis of the differential mode signal 1011, as is illustrated by the dotted lines from the differential mode signal 1011 to the controller 1020 in
The differential mode signal generator 1010 is illustrated with a dashed line and includes an adder 1013, a further adder 1014, and two polarity reversal stages 1015, or 1016, respectively. This achieves calculating a first differential mode signal 1011 as a differential signal from the left channel signal and the right channel signal and generating a further differential mode signal 1012 from the difference between the right channel and the left channel, both of which are input into the controllable amplifier 1030, which includes a first individual amplifier 1031 for the left, or first, differential mode signal, and which includes a second individual amplifier 1032 for the second, or right, differential mode signal 1012. The amplifier 1030 has an input for the adjustment value g(t) that may in this case be a voltage value derived from a signed value c (t) of the normalized cross-correlation function delivering a value range of −1 und +1. The amplifiers 1031, 1032 obtain the same adjustment value via the branching point 1033 and are configured as voltage-controlled amplifiers. For the given similarity value range between −1 und +1 converted into driver voltages, i.e. into values with the dimension volt (V), they deliver an amplification of between −10 dB und +10 dB. In the embodiment shown in
Depending on the implementation, individual amplifiers 1031, 1032 may be configured to obtain a special voltage value, a special current value, or a special digital value as the adjustment value. In such a case, the controller 1020 is configured to convert a corresponding similarity value into the voltage value, current value, or digital value needed by the amplifiers 1031, 1032 by using the table 1000. In alternative embodiments, the controllable amplifier 1030 may be configured such that it already includes a conversion by means of a table 1000. Then, with respect to the terminology of the present invention, this conversion is to be considered as being part of the controller. Thus, it is to be noted that the controller 1020 and the amplifier 1030 not necessarily have to be separate physical elements, or semiconductor elements, or separate entities, but that the definitions of these elements are functional definitions. Finally, the controllable amplifier 1030 provides two differential mode signals, i.e. a first signal 1036, 72 for the left side and a second signal 1037 for the right side.
Subsequently, an embodiment of a loudspeaker system is addressed with reference to
Subsequently, a loudspeaker is described with respect to
Furthermore, the carrier 312 comprises a tip portion having a cross-sectional area that is less than 20% of a cross-sectional area of the base portion, where the loudspeaker arrangement 314 is fixed to the tip portion. Advantageously, as illustrated in
The loudspeaker arrangement 314 has a sphere-like carrier structure 316, which is also illustrated in
Advantageously, the loudspeaker arrangement comprises at least six individual loudspeakers and particularly even twelve individual loudspeakers arranged in twelve different directions, where, in this example, the loudspeaker arrangement 314 comprises a pentagonal dodecahedron (e.g. body with 12 equally distributed surfaces) having twelve individual areas, wherein each individual area is provided with an individual loudspeaker diaphragm. Importantly, the loudspeaker arrangement 314 does not comprise a loudspeaker enclosure and the individual loudspeakers are held by the supporting structure 316 so that the diaphragms of the individual loudspeakers are freely suspended.
Furthermore, as illustrated in
Alternatively, however, the loudspeaker in
The enclosure furthermore comprises a further loudspeaker 604 which is suspended at an upper portion of the enclosure and which has a freely suspended diaphragm. This loudspeaker is a low/mid loudspeaker for a low/mid frequency range between 80 and 300 Hz and advantageously between 100 and 300 Hz. This additional loudspeaker is advantageous, since—due to the freely suspended diaphragm—the loudspeaker generates rotation stimulation/energy in the low/mid frequency range. This rotation enhances the rotation generated by the loudspeakers 314 at low/mid frequencies. This loudspeaker 604 receives the low/mid frequency portion of the signal provided to the loudspeakers at 314, e.g. the second capturing signal or the second mixed signal.
In an embodiment with a single subwoofer, the subwoofer is a twelve inch subwoofer in the closed longitudinal enclosure 300, and the loudspeaker arrangement 314 is a pentagon dodecahedron mid/high loudspeaker arrangement with freely vibratable mid frequency diaphragms.
Subsequently, an embodiment of a microphone arrangement is described with reference to
Further,
Further,
As shown further for example in
Above that, the second partial microphone 2, which includes the two diaphragms 13, 14, also comprises output lines to provide a third diaphragm signal from the third diaphragm 13 and a fourth diaphragm signal from the fourth diaphragm 14. Further, depending on the implementation, the third partial microphone is also configured to provide a fifth diaphragm signal in response to a deflection of the fifth diaphragm 15 and to provide a sixth diaphragm signal in response to a deflection of the diaphragm 16 in the third spatial axis, i.e., for example in the z direction.
The first partial microphone, the second partial microphone and, if present, the third partial microphone are configured to combine the respective diaphragm signals of the diaphragms of the diaphragm pair. This is illustrated schematically in
For generating a differential signal as, for example, the differential output signal Diffx 21, the combiner 30 is configured to combine the first diaphragm signal 11 and the second diaphragm signal 12 with a modified first phase relation. Thus, the first differential output signal Diffx 21 is allocated to the first spatial axis, for example the x-axis.
Further, the second partial microphone is configured to combine the second diaphragm signal 13 and the third diaphragm signal 14 with a modified second phase relation to provide a second differential output signal Diffy shown at 22 in
The combination is performed such as it is schematically illustrated in
The phase changing means 41 is provided to change the second phase relation for the second partial microphone such that an addition as schematically show in
Above that, also for the third partial microphone, a phase changing element 42 is provided that changes the third phase relation between the diaphragm signals 15, 16 and adds the signals with modified third phase relation to obtain the third differential output signal Diffz 23 of
As illustrated already based on reference number 24 in
The same is performed to obtain a conventional y-directional component of a directional microphone by adding the diaphragm signals of the second diaphragm pair 13, 14 with the original phase relation, i.e., without the effect of a phase member 41. Analogously, an X component of a directional microphone is obtained when the two directional characteristics, i.e., for the front diaphragm 11 and the rear diaphragm 12 are added, again without effect of a phase element 40.
An entire omnidirectional signal can be obtained when all six diaphragm signals are added in their original first second and third phase relation, wherein this omnidirectional signal, for example, is referred to as W signal or P signal as it is also known from ambisonics technology or for a signal in B-format which comprises an omnidirectional component and directional component in X-direction, a directional component in Y-direction and a Z-component in the Z-direction.
In contrary to such a B-format signal, the inventive microphone provides, in addition to these signals or as an alternative to these signals, differential signals for the individual directions, i.e., signals that result when a difference between the front and the rear directional characteristic is formed to detect the sound field which actually prevails on the side with respect to diaphragms that are arranged opposite each other, i.e., above and below the two diaphragms 11, 12 of
The change between the first phase relation on the left in
For combining such a signal, the combiner 30 is configured as illustrated in
Although such an individual combiner is illustrated in
The three partial microphones are configured such that each diaphragm comprises a counterelectrode, such that six individual diaphragms and six respective counterelectrodes exist overall in the inventive microphone shown in
An inventive re-recorded audio piece includes at least for the first channel a first pressure signal, a first directional differential signal, and a second directional differential signal; and for a second channel a second pressure signal, a third directional differential signal and fourth directional differential signal. As described and illustrated in
While this invention has been described in terms of several advantageous embodiments, there are alterations, permutations, and equivalents, which fall within the scope of this invention. It should also be noted that there are many alternative ways of implementing the methods and compositions of the present invention. It is therefore intended that the following appended claims be interpreted as including all such alterations, permutations, and equivalents as fall within the true spirit and scope of the present invention.
| Number | Date | Country | Kind |
|---|---|---|---|
| 22159907.9 | Mar 2022 | EP | regional |
This application is a continuation of copending International Application No. PCT/EP2023/055268, filed Mar. 2, 2023, which is incorporated herein by reference in its entirety, and additionally claims priority from European Application No. 22159907.9, filed Mar. 3, 2022, which is also incorporated herein by reference in its entirety. The present invention relates to the reproduction and recording of audio signals and in particular to re-recording an existing audio piece, which is also referred to as reamping.
| Number | Date | Country | |
|---|---|---|---|
| Parent | PCT/EP2023/055268 | Mar 2023 | WO |
| Child | 18823452 | US |
