JP5743003B2 - Wavefront synthesis signal conversion apparatus and wavefront synthesis signal conversion method - Google Patents

Description

  The present invention relates to a wavefront synthesis signal conversion apparatus and a wavefront synthesis signal conversion method.

  Stereo reproduction systems that reproduce multi-channel audio signals using a plurality of speakers in order to reproduce realistic sounds are widely known. For example, a 5.1 channel surround system reproduces sound using five speakers and one subwoofer speaker. Speakers are arranged in accordance with the ITU-R BS775 (International Telecommunication Union Radiocommunications Sector) specifications, and different sound waves are output from the speakers corresponding to each channel, and the listener listens to them, thereby making the listener feel more realistic. You can enjoy a certain sound.

  A stereo reproduction system such as a 5.1 channel surround system can obtain a target sound image localization at a predetermined listening position. However, since such a stereo reproduction system has a narrow range in which the target sound image localization can be obtained, the reproduction sound that the listener hears is heard at the predetermined listening position in places other than the predetermined listening position. Compared to the playback sound to be greatly different.

  Therefore, there is a multi-channel audio system for the purpose of physically reproducing the sound field itself in which the original sound source exists in space. The multi-channel audio system records the wavefront created by the sound source in the original sound field, and reproduces the wavefront in a space different from the current sound field based on the recorded wavefront. The multi-channel audio system uses a wavefront synthesis technique, which is a sound case generation technique, and outputs sound waves from an array speaker composed of a plurality of speakers. The outputted sound wave is transmitted to the listener as a wave without interference. When the listener hears the sound wave, the listener can enjoy a realistic sound.

  In order to reproduce the wavefront in a wide band, it is necessary to narrow the microphone interval of the microphone array for recording the wavefront and the speaker interval of the array speaker for reproducing the wavefront to several centimeters or less. The speaker spacing can be increased to some extent by the technique disclosed in Patent Document 1. Further, when reproducing a sound such as a reflected sound coming from behind the listener, it is necessary to arrange an array speaker for reproduction so as to surround the listener's listening area. With this technology, it is possible to reproduce sound coming from behind the listener only with the array speaker arranged in front of the listener.

In a multi-channel audio system that uses wavefront synthesis technology, without recording the wavefront information in the actual sound field, the sound source that is the current sound field and the sound field in the room where it exists are assumed to be fictitious. Wavefront synthesis can also be performed by arranging a plurality of signals recorded alone as virtual sound sources in an imaginary room. By performing wavefront synthesis in this way, the sound field that these sound sources will create can be reproduced in an actual room.

  Even in the case of a speaker arrangement of a 5.1 channel surround system, for example, Patent Document 3 discloses a technique for performing pseudo wavefront synthesis. The technique disclosed in Patent Document 3 uses a plurality of monophonic or directional sounds that reproduce a sound field through spatial harmonics that substantially exactly match the spatial harmonics of the original sound field via a plurality of loudspeakers. A method for recording or transmitting a sound field from a signal. In this technique, monophonic sound sources are processed by mastering so that all loudspeaker channels contribute to sound in order to preserve spatial harmonics. If the loudspeaker configuration is different from what was assumed during mastering, the loudspeaker signal will be the spatial harmonics of the sound field reproduced by the different loudspeaker configurations. It is reprocessed at the playback location (home, etc.) to match the wave. By reprocessing in this way, it is possible to reproduce an original sound field that performs pseudo wavefront synthesis.

Japanese Patent Laid-Open No. 2005-80079 JP 2007-184818 A Special table 2003-53555 gazette

  However, in the 5.1 channel surround system, as defined in ITU-R BS775, the listener needs to listen to the sound at the center of the arranged speakers. Accordingly, there is a problem that it is impossible to reproduce a realistic sound for other listeners who listen at a place other than the center. In addition, the 5.1 channel surround system does not physically reproduce the sound field itself where the original sound source existed, but uses the psychoacoustic phenomenon of the listener so that there is a sense of presence when listening with both ears. I aim to make them perceive. Therefore, there is a problem that the effect differs depending on the listener.

  Further, in the case of reproduction by the wavefront synthesis technique, it is necessary to perform sound recording and wavefront synthesis signal processing in accordance with the speaker interval, arrangement, and configuration of the array speaker that outputs sound. Therefore, a multi-channel signal created for a specific speaker interval, arrangement and configuration cannot be reproduced as expected in a multi-channel audio system having other speaker intervals, arrangement and configuration.

  In the technique of Patent Document 3 in which wavefront synthesis is performed in a pseudo manner in a 5.1 channel surround system, mathematically, a spatial impulse representing a sound source position is accurately represented by a number of orders. It is assumed that only one speaker is used. For this reason, there is a limit to the number of spatial harmonics that can be included in the reproduced sound field, and the system of wavefront synthesis is very bad. Therefore, although the direction perception and the sense of presence in the direction of sound arrival are somewhat improved compared to the conventional 5.1 channel surround system, it is as if the instrument is sounding near or far from the listener in the original sound field. It was also difficult for listeners who listened at places other than the center to experience a sense of reality.

  If the information of the sound source position, the sound source signal and the assumed listening area (the number of speakers and the speaker interval) is known, based on the information, the reproduction system specifications, for example, the signal processing capability, the number of speakers and the speaker interval, There has also been proposed a technique for creating a wavefront synthesized reproduction signal by converting a sound source position and a sound source signal. However, in the case of this technology, there is a problem that the wavefront synthesized reproduction signal for reproduction cannot be calculated unless the information of the sound source position, the sound source signal, and the assumed listening area (number of speakers and speaker spacing) are all known in advance. there were.

  Therefore, the present invention has been made in view of the above problems, and an object of the present invention is to produce wavefront synthesis content when reproducing a realistic sound field using, for example, wavefront synthesis technology. New and improved wavefront that can calculate the wavefront synthesized playback signal based on the specifications of the number of speakers and speaker spacing assumed when the It is an object of the present invention to provide a combined signal conversion apparatus and a wavefront combined signal conversion method.

  In order to solve the above-described problem, according to an aspect of the present invention, there is provided a wavefront synthesis signal conversion apparatus that converts a wavefront synthesis reproduction signal for which a wavefront synthesis reproduction condition is specified so as to suit different wavefront synthesis reproduction conditions. A wavefront synthesis reproduction condition information input unit for inputting wavefront synthesis reproduction condition information which is a reproduction condition of a wavefront synthesis reproduction signal including at least reproduction speaker arrangement information, and a wavefront synthesis reproduction signal input for inputting wavefront synthesis reproduction signals of a plurality of channels The wavefront synthesis reproduction signal input from the wavefront synthesis reproduction signal input unit is different from the wavefront synthesis reproduction condition, with the reproduction speaker position of each channel obtained from the wavefront synthesis reproduction condition information as the primary sound source position for wavefront synthesis. A wavefront synthesis reproduction signal conversion unit for converting into a wavefront synthesis reproduction signal for a new wavefront synthesis speaker having a speaker arrangement of each channel. Wherein, wave field synthesis signal converter is provided.

  According to such a configuration, the wavefront synthesis reproduction condition information input unit inputs wavefront synthesis reproduction condition information that is a reproduction condition of a wavefront synthesis reproduction signal including at least reproduction speaker arrangement information, and the wavefront synthesis reproduction signal input unit includes a plurality of channels. The wavefront synthesis reproduction signal is input, and the wavefront synthesis reproduction signal conversion unit is input from the wavefront synthesis reproduction signal input unit with the reproduction speaker position of each channel obtained from the wavefront synthesis reproduction condition information as the primary sound source position of wavefront synthesis. The wavefront synthesis reproduction signal is converted into a wavefront synthesis reproduction signal for a new wavefront synthesis speaker having a speaker arrangement of each channel different from the wavefront synthesis reproduction condition. As a result, even if playback is performed with a speaker having specifications different from the wavefront synthesis playback conditions specified in the wavefront synthesis playback signal, a predetermined playback sound field can be reproduced without having to regenerate the wavefront synthesis signal.

  The new wavefront synthesis speaker is a linear array speaker, and the wavefront synthesis reproduction signal converter reproduces the wavefront from the primary sound source position with a new wavefront synthesis speaker having a speaker arrangement of each channel different from the wavefront synthesis reproduction conditions. The wavefront synthesis filter coefficient for performing the calculation is filtered, and the wavefront synthesis reproduction signals of a plurality of channels input from the wavefront synthesis reproduction signal input unit are filtered. As a result, it is possible to reproduce the specified playback sound field even if playback is performed with a speaker having specifications different from the wavefront synthesis playback conditions specified in the wavefront synthesis playback signal. Can be reproduced.

  The wavefront synthesis reproduction condition information input unit inputs the number of speaker channels and the speaker interval as reproduction information of the input wavefront synthesis reproduction signals of a plurality of channels. As a result, it is possible to synthesize a desired sound field even with a playback device having a different number of speaker channels and different speaker intervals as the playback information of the wavefront synthesis playback signals of a plurality of input channels.

  The wavefront synthesis reproduction signal conversion unit separates frequency components that exceed the upper limit frequency of wavefront synthesis in the speaker arrangement of a new wavefront synthesis speaker from the wavefront synthesis reproduction signals of a plurality of channels input by the wavefront synthesis reproduction signal input unit. Each channel converted by the wavefront synthesis reproduction signal conversion unit, the highband frequency component channel allocation unit for assigning the wavefront synthesis signal component separated by the highband frequency separation unit to the channel of the new wavefront synthesis speaker, A signal mixing unit for mixing the wavefront synthesized reproduction signal and the high frequency component signal assigned to each channel by the high frequency component channel allocating unit. As a result, a signal including a frequency component higher than the upper limit frequency capable of wavefront synthesis can be added so as not to disturb the sound image perception in the wavefront synthesis frequency band, so that a more natural timbre can be reproduced.

  In order to solve the above problems, according to another aspect of the present invention, there is provided a wavefront synthesis reproduction apparatus for reproducing a wavefront synthesis reproduction signal for which a wavefront synthesis reproduction condition is specified, wherein at least reproduction speaker arrangement information is obtained. A wavefront synthesis reproduction condition information input unit for inputting reproduction condition information of a wavefront synthesis reproduction signal including the wavefront synthesis reproduction signal input unit for inputting a wavefront synthesis reproduction signal of a plurality of channels, and each channel obtained from the wavefront synthesis reproduction condition information A wavefront synthesis reproduction signal conversion unit for converting the reproduced speaker position into a wavefront synthesis reproduction signal for a new wavefront synthesis speaker having a speaker arrangement of each channel different from the wavefront synthesis reproduction condition, with the position of the reproduction speaker as a primary sound source position for wavefront synthesis; A wavefront synthesis speaker that converts the signal converted by the wavefront synthesis reproduction signal conversion unit into an acoustic signal and outputs the sound signal, and a plurality of channels obtained by the wavefront synthesis reproduction signal input unit. A wavefront synthesis reproduction control unit for controlling the reproduction of the wavefront synthesis reproduction signal of the signal, and the wavefront synthesis reproduction control unit includes a speaker among the reproduction condition information of the wavefront synthesis reproduction signal obtained by the wavefront synthesis reproduction condition information input unit. When the number of channels and the speaker spacing do not match the number of speaker channels and the speaker spacing of the wavefront synthesis speaker, the wavefront synthesis playback signal conversion unit converts the wavefront synthesis playback signals of multiple channels obtained by the wavefront synthesis playback signal input unit. If it is re-synthesized to be suitable for the playback device and then sent to the wavefront synthesis speaker, and if it matches the number of speaker channels and the speaker interval of the wavefront synthesis speaker, multiple channels obtained at the wavefront synthesis playback signal input unit The wavefront synthesis reproduction is characterized in that it is controlled to send the wavefront synthesis reproduction signal to the wavefront synthesis speaker without recombining. Apparatus is provided.

  According to this configuration, the wavefront synthesis reproduction condition information input unit inputs the reproduction condition information of the wavefront synthesis reproduction signal including at least reproduction speaker arrangement information, and the wavefront synthesis reproduction signal input unit inputs the wavefront synthesis reproduction signal of a plurality of channels. Then, the wavefront synthesis reproduction signal conversion unit sets the reproduction speaker position of each channel obtained from the wavefront synthesis reproduction condition information as the primary sound source position of the wavefront synthesis, and has a new speaker arrangement of each channel different from the wavefront synthesis reproduction condition. Convert to wavefront synthesis playback signal for wavefront synthesis speaker. The wavefront synthesis reproduction control unit compares the specifications of the wavefront synthesis speaker with the wavefront synthesis reproduction condition information, and controls the wavefront synthesis reproduction signal conversion unit to convert the wavefront synthesis reproduction signal if the conditions are different. As a result, it is possible to compare the reproduction conditions for the wavefront synthesis reproduction signal with the specifications of the wavefront synthesis reproduction apparatus, and to convert the wavefront synthesis reproduction signal as necessary.

  The wavefront synthesis reproduction signal conversion unit separates frequency components that exceed the upper limit frequency of wavefront synthesis in the speaker arrangement of a new wavefront synthesis speaker from the wavefront synthesis reproduction signals of a plurality of channels input by the wavefront synthesis reproduction signal input unit. Each channel converted by the wavefront synthesis reproduction signal conversion unit, the highband frequency component channel allocation unit for assigning the wavefront synthesis signal component separated by the highband frequency separation unit to the channel of the new wavefront synthesis speaker, A signal mixing unit for mixing the wavefront synthesized reproduction signal and the high frequency component signal assigned to each channel by the high frequency component channel allocating unit. As a result, a signal including a frequency component higher than the upper limit frequency capable of wavefront synthesis can be added so as not to disturb the sound image perception in the wavefront synthesis frequency band, so that a more natural timbre can be reproduced.

  As a result, a predetermined reproduction sound field can be reproduced even if reproduction is performed with a speaker having a specification different from the wavefront synthesis reproduction condition specified in the wavefront synthesis reproduction signal, so that there is no need to recreate the wavefront synthesis signal.

  In order to solve the above-mentioned problem, according to still another aspect of the present invention, a wavefront synthesis signal conversion for converting a wavefront synthesis reproduction signal for which a wavefront synthesis reproduction condition is specified to suit different wavefront synthesis reproduction conditions. A wavefront synthesis reproduction condition information input step for inputting wavefront synthesis reproduction condition information which is a reproduction condition of a wavefront synthesis reproduction signal including at least reproduction speaker arrangement information, and a wavefront for inputting a wavefront synthesis reproduction signal of a plurality of channels. The wavefront synthesis playback signal input in the wavefront synthesis playback signal input step is set to the wavefront synthesis playback signal input step, with the playback speaker position of each channel obtained from the wavefront synthesis playback condition information as the primary sound source position of the wavefront synthesis. Wavefront synthesis to convert to a wavefront synthesis playback signal for a new wavefront synthesis speaker with different channel placement for each channel Characterized in that it comprises a raw signal conversion step, the wavefront synthesis signal conversion method are provided.

  According to this configuration, the wavefront synthesis reproduction condition information input step inputs wavefront synthesis reproduction condition information that is a reproduction condition of a wavefront synthesis reproduction signal including at least reproduction speaker arrangement information, and the wavefront synthesis reproduction signal input unit step includes a plurality of channels. The wavefront synthesized reproduction signal conversion step is input in the wavefront synthesized reproduction signal input step with the reproduction speaker position of each channel obtained from the wavefront synthesis reproduction condition information as the primary sound source position of wavefront synthesis. The wavefront synthesis reproduction signal is converted into a wavefront synthesis reproduction signal for a new wavefront synthesis speaker having a speaker arrangement of each channel different from the wavefront synthesis reproduction condition. As a result, even if playback is performed with a speaker having specifications different from the wavefront synthesis playback conditions specified in the wavefront synthesis playback signal, a predetermined playback sound field can be reproduced without having to regenerate the wavefront synthesis signal.

  As described above, according to the present invention, when reproducing a sound field with a sense of presence using wavefront synthesis technology, from the specifications of the number of speakers and speaker spacing assumed when the wavefront synthesis content was produced, It is possible to provide a new and improved wavefront synthesis signal conversion apparatus and wavefront synthesis signal conversion method capable of calculating a wavefront synthesis reproduction signal in accordance with a playback apparatus actually used and reproducing a synthesized sound field. .

It is explanatory drawing explaining the example of the array speaker for wave front synthetic | combination reproduction | regeneration assumed by the content producer, and a standard listening position. It is explanatory drawing explaining the example of an array speaker different from the array speaker for wave front synthetic | combination reproduction | regeneration which the content producer assumed. It is explanatory drawing explaining another example of the array speaker different from the array speaker for wave front synthetic | combination reproduction | regeneration assumed by the content producer. It is explanatory drawing explaining the setting of the wavefront synthetic | combination filter concerning one Embodiment of this invention. It is explanatory drawing explaining an example in the case of outputting the sound of a frequency component higher than a wavefront synthetic | combination upper limit frequency from an array speaker. It is explanatory drawing explaining another example in the case of outputting the sound of a frequency component higher than a wavefront synthetic | combination upper limit frequency from an array speaker. It is explanatory drawing explaining allocation of the speaker unit which takes charge of the high frequency component exceeding a wave-front synthetic | combination frequency band. It is explanatory drawing explaining the sound field reproducing | regenerating apparatus 10 concerning one Embodiment of this invention. It is explanatory drawing explaining the structure of the wave field synthetic | combination reproduction | regeneration signal conversion part 130 concerning one Embodiment of this invention. It is explanatory drawing explaining the change of a wavefront synthetic | combination upper limit frequency.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. In addition, in this specification and drawing, about the component which has the substantially same function structure, duplication description is abbreviate | omitted by attaching | subjecting the same code | symbol.

  First, a wavefront synthesis technique using an array speaker will be described. To reproduce a sound field by wavefront synthesis using an array speaker, a multichannel reproduction signal (wavefront synthesis reproduction signal) to be supplied to an array speaker system consisting of a plurality of speaker units is generated, and the multichannel reproduction signal is generated. To output sound from each speaker unit. The sounds output from the individual speaker units are synthesized in space and reproduced so that sound waves arrive at the listener from the direction of the target sound source.

  In other words, multi-channel playback signals are designed to reproduce the wavefront when sound is output from an array speaker system. For example, Takeda et al., “Study on wavefront synthesis using multi-channel speaker playback” A signal created by a method as described in the conference proceedings, pp 407-408, September 2000, can be used as a multi-channel signal. Since the wavefront coming from the sound source is reproduced in the listening area, the sound image can be localized at a predetermined position in a wide listening range.

  FIG. 1 is an explanatory diagram for explaining an example of an array speaker for wavefront synthesis reproduction and a standard listening position assumed by a content producer who produces video and audio (hereinafter, video and audio are also collectively referred to as “content”). It is. In FIG. 1, an array speaker with 24 channels and an interval of 8 cm is described as an example of the array speaker 1 for wavefront synthesis reproduction. Further, the standard listening position 2 assumed by the content producer is a position 2 m away from the center of the array speaker 1.

  The content producer arranges the performance sound of the musical instrument as a primary sound source so as to be suitable for the array speaker 1 as shown in FIG. 1, and produces content that reproduces a realistic sound field by wavefront synthesis. .

  Usually, the primary sound source is arranged inside the line passing through the standard listening position 2 and the speaker unit at the end of the array speaker 1 and at a position 1 m or more away from the listener side from the array speaker 1. For example, in the example shown in FIG. 1, the area where the primary sound source is arranged is defined as the area inside the dotted line indicated by reference numeral 3 in FIG. In FIG. 1, the area setting is such that the area where the primary sound source is arranged is also limited in the depth direction. This is due to the nature of distance perception by human hearing, and the effect on the distance perception of wavefront information becomes small when moving away from the sound source by about 3 to 5 meters, and the close distance depends on the level of the incoming sound and the degree of reflection / reverberation. Therefore, the sound source when reproducing the sound field by wavefront synthesis is arranged at a position 3 to 5 m away from the standard listening position 2, and the sound source farther than that is used for level adjustment and reflection / reverberation sound. This is because it can be dealt with by adjusting the addition of.

  The primary sound source can include a sound reflected directly from a wall surface provided virtually or a reverberation sound as a sound source to be reproduced by wavefront synthesis in addition to the sound that directly arrives at the listener. For example, when the sound source a (symbol 4a) is arranged as the primary sound source, another sound source a '(symbol 4a') can be arranged as the sound source a reflected from the wall surface behind the stage. In this case, the sound source a 'is arranged by adding a time delay or reverberation processing to the sound source a.

  FIG. 2 is an explanatory diagram for explaining an example of an array speaker different from the array speaker for wavefront synthesis reproduction assumed by the content producer (for example, the array speaker 1 shown in FIG. 1). In FIG. 2, the array speaker 1a for wavefront synthesis reproduction is described with an example of an array speaker of 16 channels and 6 cm intervals.

  The array speaker 1a shown in FIG. 2 is different in configuration from the array speaker 1 assumed by the content producer, so that the content produced assuming the array speaker shown in FIG. 1 and the standard listening position cannot be reproduced as it is. Can not.

  FIG. 3 is an explanatory diagram for explaining another example of an array speaker different from the array speaker for wavefront synthesis reproduction assumed by the content producer (for example, the array speaker 1 shown in FIG. 1). In FIG. 3, as an array speaker 1b for wavefront synthesis reproduction, an array speaker with 8 channels and 6 cm intervals is described as an example.

  Since the array speaker 1b shown in FIG. 3 is different in configuration from the array speaker 1 assumed by the content producer, similarly to the array speaker 1a shown in FIG. 2, the array speaker shown in FIG. 1 and the standard listening position are assumed. The content produced in this way cannot be played back as it is.

  In this embodiment, in order to reproduce the content produced assuming the array speaker and the standard listening position shown in FIG. 1 with an array speaker different from those assumed as shown in FIGS. A wavefront synthesized signal conversion apparatus and a wavefront synthesized signal conversion method for reproducing a reproduced signal by an array speaker different from the assumed array speaker will be described.

  In order to show the positional relationship between the array speakers 1a and 1b shown in FIGS. 2 and 3 and the array speaker 1 shown in FIG. 1, the array speakers 1 are shown by dotted lines in FIGS. By setting such a positional relationship, the standard listening position 2 synthesizes a sound field as if the original array speaker 1 exists, and the sound generated by wavefront synthesis is emitted from the array speaker 1, thereby producing content. It is possible to listen to the sound that comes from the original primary sound source assumed by the person.

  In such a case, the position of each speaker channel of the original array speaker 1 for wavefront synthesis is set as a new primary sound source position, and the sound wave radiated from the new primary sound source position is actually used as an array speaker. Reproduced by synthesis of sound wave surfaces from 1a and 1b. For this purpose, a wavefront synthesis filter that is reproduced by synthesis of sound wavefronts from the array speakers 1a and 1b is inserted as a wavefront synthesis reproduction speaker conversion filter in front of the array speakers 1a and 1b.

FIG. 4 is an explanatory diagram illustrating the setting of the wavefront synthesis filter according to the embodiment of the present invention. FIG. 4 illustrates a method of generating a wavefront synthesis filter for reproducing the sound field that is emitted from the original primary sound source assumed by the content producer with the array speaker 1a shown in FIG. . Specifically, the speaker units u ₁ , u ₂ ,..., U ₂₄ of each channel of the array speaker 1 are used as the primary sound source, and the wave front radiated from each speaker unit is reproduced using the array speaker 1a. wavefront synthesis filter _h 1.1 _{for, h 1.2, ···, h 1.16} , h 2.1, h 2.2, ···, h 2.16, ···, h 24 _.. , H _24.2 ,..., H _24.16 will be described.

A transfer characteristic from a primary sound source, for example, u ₁ to a control point j in a control area provided in front of the array speaker 1a is represented by a1 _{. If j} is j, the response at the control point j by the primary sound source u ₁ is u ₁ · a _{1. j} (see FIG. 4A).

On the other hand, 16 of the speaker units _{w 1,} w 2, · · _·, response array speaker 1a consisting of _{w 16} makes the control point j, the control point from the speaker unit _{w 1, w 2, ···,} w 16 transfer characteristics up to _j , c _{j. 1} , c _{j. 2} ,... C _{j. 16} and u ₁ · h _1.1 · c _{j. 1} +... + U ₁ · h _{1. k} · c _{j. k} +... + u ₁ · h _1.16 · c _{j. 16} (see FIG. 4B).

Wave field synthesis filter relating to the primary source u _1, for all control points of the control area, the original sound field so that the difference of the response by the response and the wavefront synthesis (original sound field), that is, reproduction error is minimized Calculate. Details are prepared by the method described in, for example, Takeda et al., “Study on wavefront synthesis using multi-channel loudspeaker reproduction” mentioned above, pp407-408, September 2000. be able to.

  By creating a wavefront synthesis filter in this way, a sound field is synthesized as if the original array speaker 1 exists at the standard listening position 2 and sound from the wavefront synthesis is radiated from the array speaker 1, You can listen to the sound that comes from the original primary sound source assumed by the producer.

The conversion process described above applies only to frequency components lower than the wavefront synthesis upper limit frequency at which wavefront synthesis can be performed with high accuracy. The wavelength at which wavefront synthesis can be performed accurately is when the speaker unit interval is shorter than ½ wavelength, that is, when the wavelength is longer than twice the speaker interval. Accordingly, the wavefront synthesis upper limit frequency f _h is calculated by f _h = {(340/2) / speaker unit interval} [Hz] when the sound speed is 340 m / sec.

In practice, the angle θ between the sound wavefront and the array speaker, as shown in FIG. 1, limits the upper limit of the θ value if the arrangement range of the primary sound source is limited. Therefore, as shown in FIG. 10, the wavefront synthesis upper limit frequency f _h rises by 1 / sin θ times. That is, when θ is 90 degrees, sin θ = 1, so the wavefront synthesis upper limit frequency f _h90 is f _h90 = {(340/2) / speaker unit interval} [Hz], and wavefront synthesis at other angles The upper limit frequency f _h is f _h = f _h90 × 1 / sin θ [Hz].

  Therefore, the sound source by the actual wavefront synthesis is often made so as to output a frequency higher than the wavefront synthesis upper limit frequency from the array speaker.

  FIG. 5 is an explanatory diagram for explaining an example of the case where sound having a frequency component higher than the wavefront synthesis upper limit frequency is output from the array speaker. In the example shown in FIG. 5, for the high frequency component, the left and right level differences are controlled using the speaker units located at both ends of the array speaker 1 as in the case of intensity stereo.

  Further, even in the case of the array speakers 1a and 1b shown in FIGS. 2 and 3, the left and right level differences may be controlled using the speaker units at both ends similarly to the intensity stereo. In these cases, the difference in position with the standard array speaker 1 is set downward so that the wavefront synthesis frequency band component for performing wavefront synthesis and the high frequency component reach the standard listening position 2 in synchronization. It is desirable to adjust the axis.

  Strictly speaking, at a listening position away from the assumed standard listening position 2, there is a time difference between the wavefront synthesis frequency band component and the high frequency component, but this is important for sound image localization determination and has a large energy. Since the mid- and low-frequency components are accurately generated by wavefront synthesis, and the sound image is perceived by sound synthesis, the time difference between the wavefront synthesis frequency band component and the high-frequency component makes the sound image unnatural. There is nothing.

  FIG. 6 is an explanatory diagram for explaining another example in the case where a sound having a frequency component higher than the wavefront synthesis upper limit frequency is output from the array speaker. In the example shown in FIG. 6, when a primary sound source including a high frequency component is output from the speaker unit of the array speaker in the direction closest to the primary sound source direction when viewed from the standard listening position 2, the high frequency component is output. Is described.

  For example, as shown in FIG. 6, when there are primary sound sources A, B, and C including high frequency components, from the fifth speaker unit of the 24-channel array speaker 1 assumed as a standard by the content producer. The high frequency component of the primary sound source A is output. Similarly, the high frequency component of the primary sound source B is output from the 9th speaker unit, and the high frequency component of the primary sound source C is output from the 21st speaker unit.

  Similarly, even in the case of the array speakers 1a and 1b different from those assumed as standard, the high frequency component from the speaker unit of the array speaker in the direction closest to the primary sound source direction when viewed from the standard listening position 2 Is output. For example, if the array speaker 1a has 16 channels, the high frequency component of the primary sound source A is output from the fourth speaker unit, and the high frequency component of the primary sound source B is output from the sixth speaker unit. The high frequency component of the primary sound source C is output from the 14th speaker unit. Further, in the case of the 8-channel array speaker 1b, the high frequency component of the primary sound source A is output from the second speaker unit, and similarly, the high frequency component of the primary sound source B is output from the third speaker unit. The high frequency component of the primary sound source C is output from the No. 7 speaker unit.

  In FIG. 6, the locations of the original primary sound sources A, B, and C are known. However, it is difficult to know the position of the original primary sound source from the 24-channel signal for wavefront synthesis. In such a case, the standard 24-channel speaker unit is used as a new primary sound source, so that the direction in which the 24-channel speaker unit can be seen from the standard listening position 2 is as similar as possible. Assign a signal to the speaker unit.

  FIG. 7 is an explanatory diagram for explaining assignment of speaker units responsible for high frequency components exceeding the wavefront synthesis frequency band. The numbers given to the speaker units of the array speakers 1 a and 1 b in FIG. 7 represent the numbers of the speaker units of the array speaker 1.

  Referring to FIG. 7, the assignment of speaker units responsible for high frequency components will be described. In the case of a 16-channel array speaker 1a, the first speaker unit of the array speaker 1 is assigned to the first speaker unit from the left. Hereinafter, the second speaker unit is sequentially assigned to the second speaker unit of the array speaker 1 and the third speaker unit, the third speaker unit is the fourth speaker unit of the array speaker 1, and so on. Similarly, in the case of the 8-channel array speaker 1b, the first and second speaker units of the array speaker 1 are assigned to the first speaker unit from the left. In the following, the third speaker unit of the array speaker 1 to the fifth speaker unit of the array speaker 1 is assigned to the second speaker unit, the sixth speaker unit of the array speaker 1 to the ninth speaker unit of the array speaker 1,.

  At this time, in order to synchronize the timing with the wavefront synthesis frequency band component, the time axis is adjusted based on the position difference from the standard array speaker 1. In this way, by assigning speaker units responsible for high frequency components exceeding the wavefront synthesis frequency band, even if sound is output from an array speaker different from the standard, the sound field is synthesized by wavefront synthesis. Can be played.

  Which of the two examples described above is used by the actual wavefront synthesis sound source can be determined by frequency analysis of all the channels of the content reproduced by wavefront synthesis. Therefore, by performing frequency analysis before content reproduction, it is possible to set processing for high frequency by determining which example is used to perform processing for high frequency.

  The wavefront synthesis signal conversion apparatus and the wavefront synthesis signal conversion method according to an embodiment of the present invention are based on such a technical idea. Hereinafter, a wavefront synthesis signal conversion apparatus and a wavefront synthesis signal conversion method according to an embodiment of the present invention will be described in detail.

  Next, details of the wavefront synthesis signal conversion apparatus and the wavefront synthesis signal conversion method according to the embodiment of the present invention will be described. FIG. 8 is an explanatory diagram for explaining the sound field reproducing apparatus 10 according to the embodiment of the present invention. Hereinafter, the configuration of the sound field reproducing apparatus 10 according to the embodiment of the present invention will be described with reference to FIG.

  As shown in FIG. 8, the sound field reproduction device 10 according to the embodiment of the present invention includes a data input unit 110, a data decoding unit 112, a demultiplexing unit 114, an audio data decoding unit 120, Data decoding unit 122, wavefront synthesis reproduction signal conversion unit 130, audio output unit 150, subtitle data decoding unit 170, subtitle reproduction unit 172, video data decoding unit 180, video reproduction unit 182 and subtitle super-in A pose unit 190 and a display unit 192 are included. The audio output unit 150 includes an amplifier 152 and an array speaker 154.

  The data input unit 110 inputs content data (video data and audio data) to be played back by the sound field playback device 10. The input source of the content data may be, for example, a CD-ROM, DVD-ROM, or other optical disk having a large capacity of several hundred mega to several gigabytes or data received via a network. The content data input to the data input unit 110 is encoded by a predetermined encoding method, and the capacity is compressed. The content data input by the data input unit 110 is sent to the data decryption unit 112.

  The data decoding unit 112 receives the content data input by the data input unit 110, decodes the data encoded by a predetermined encoding method using a decoding method corresponding to the encoding method, and outputs the decoded data. . The data decoded by the data decoding unit 112 is sent to the demultiplexing unit 114.

  The demultiplexing unit 114 performs demultiplexing processing on the data decoded by the data decoding unit 112 and extracts video data, audio data, caption data, and metadata. Each extracted data is sent to the audio data decoding unit 120, the metadata decoding unit 122, the caption data decoding unit 170, and the video data decoding unit.

  The audio data decoding unit 120 decodes and extracts audio data from the signal demultiplexed by the demultiplexing unit 114. The audio data extracted by the audio data decoding unit 120 includes m-channel audio information and sound source position information for forming a virtual sound source. The audio information can include information such as the type and output level of each virtual sound source and the duration of the sound. A signal related to the audio data extracted by the audio data decoding unit 120 is referred to as a wavefront synthesis reproduction signal.

  The metadata decoding unit 122 decodes and extracts metadata for reproducing audio data, accompanying the content data, from the signal demultiplexed by the demultiplexing unit 114. The metadata extracted by the metadata decoding unit 122 includes standard reproduction condition data assumed by the content producer. The standard reproduction condition data includes information on the number of speaker channels, the interval between speaker units constituting the array speaker, and the standard listening position.

  The standard listening position information may be set as an absolute distance from the center position of the array speaker, and the array speaker's total length calculated from the product of the speaker unit interval and the number of speaker channels is used as the reference. The distance from the center position may be set. When setting the standard listening position information as the distance from the center position of the array speaker with reference to the total length of the array speaker, for example, the distance from the center position of the array speaker is set to 1 to 2 times the total length of the array speaker. You may set between.

  The wavefront synthesis reproduction signal conversion unit 130 receives data output from the audio data decoding unit 120 and the metadata decoding unit 122, converts the data into a wavefront synthesis reproduction signal suitable for the configuration of the sound field reproduction device 10, and outputs the wavefront synthesis reproduction signal. It is.

  The wavefront synthesis reproduction signal conversion unit 130 includes the number of channels of the speaker of the sound field reproduction device 10 and the interval between speaker units constituting the array speaker (hereinafter, the number of channels of the speaker of the sound field reproduction device 10 and the speaker constituting the array speaker). The interval between the units is also collectively referred to as “actual playback condition”) from the audio output unit 150. When the assumed playback condition and the actual playback condition are different by using the playback condition assumed by the content producer and the actual playback condition, as described above, the speaker unit under the assumed playback condition. It is possible to calculate a wavefront synthesis filter whose position is the primary sound source position in the sound field reproducing apparatus 10 that actually reproduces the position. By calculating the wavefront synthesis filter, the wavefront synthesis reproduction signal conversion unit 130 can perform a wavefront synthesis reproduction signal conversion process for obtaining a wavefront synthesis reproduction signal suitable for the actual reproduction environment.

  If the assumed reproduction condition and the actual reproduction condition match, the wavefront synthesis reproduction signal conversion unit 130 does not perform the wavefront synthesis reproduction signal conversion process and is extracted by the audio data decoding unit 120. The wavefront synthesis reproduction signal may be input to the audio output unit 150 as it is.

  The amplifier 152 amplifies the wavefront synthesis reproduction signal generated by the wavefront synthesis reproduction signal conversion unit 130 for reproduction by the array speaker 154. The array speaker 154 outputs sound from n speaker units (not shown). The sound output from the array speaker 154 is wavefront synthesized to form a wavefront. Further, by outputting sound from the array speaker 154 by wavefront synthesis, a sound source can be virtually arranged in the space, and a sound field in which sound is emitted from the sound source can be reproduced.

  The caption data decoding unit 170 decodes and extracts caption data from the signal demultiplexed by the demultiplexing unit 114. The caption playback unit 172 plays back the caption data extracted by the caption data decoding unit 170. The video data decoding unit 180 decodes and extracts video data from the signal demultiplexed by the demultiplexing unit 114. The video playback unit 182 plays back the video data extracted by the video data decoding unit 180. The caption superimposing unit 190 performs processing for superimposing caption data on video data. The display unit 192 displays video data on which caption data is superimposed.

  When the number of speaker units of the array speaker 154 and the interval between the speaker units are different from those assumed by the content producer, the sound field reproduction device 10 according to the embodiment of the present invention can generate a wavefront synthesized reproduction signal. By converting the wavefront synthesized reproduction signal for obtaining the wavefront synthesized reproduction signal suitable for the actual reproduction environment by the conversion unit 130, it is possible to reproduce the sound field as assumed by the content producer.

  In this embodiment, the display unit 192 is configured as a part of the sound field reproduction device 10, but the data from the caption superimposing unit 190 is output to an external video display device such as a liquid crystal display or a plasma display. You may make it do.

  The configuration of the sound field reproduction device 10 according to the embodiment of the present invention has been described above with reference to FIG. Next, the configuration of the wavefront synthesis reproduction signal conversion unit 130 according to the embodiment of the present invention will be described.

  FIG. 9 is an explanatory diagram illustrating the configuration of the wavefront synthesis reproduction signal conversion unit 130 according to the embodiment of the present invention. Hereinafter, the configuration of the wavefront synthesis reproduction signal conversion unit 130 according to the embodiment of the present invention will be described with reference to FIG.

  As shown in FIG. 9, the wavefront synthesis reproduction signal converter 130 according to the embodiment of the present invention includes a frequency analyzer 132, a frequency band separator 134, a filter coefficient generator 136, a high frequency component channel. An allocation unit 138, a wavefront synthesis reproduction signal generation unit 140, and a signal mixing unit 142 are configured.

  The frequency analysis unit 132 inputs the audio data extracted by the audio data decoding unit 120 and analyzes the frequency of the reproduced audio. The analysis result is sent to the high frequency component channel allocation unit 138.

  The frequency band separation unit 134 receives the audio data extracted by the audio data decoding unit 120 and the actual reproduction condition data sent from the audio output unit 150, and has a frequency component higher than a wavefront synthesis upper limit frequency and a component with a lower frequency. Are output separately. The component of the frequency band higher than the wavefront synthesis upper limit frequency is sent to the high frequency component channel allocation unit 138, and the component of the frequency band lower than the wavefront synthesis upper limit frequency (wavefront synthesis band) is sent to the wavefront synthesis reproduction signal generation unit 140.

  As described above, the wavefront synthesis upper limit frequency also changes depending on the angle θ between the array speaker surface and the wavefront (see FIG. 10), but the original primary sound source is derived from a multi-channel sound source already created for wavefront synthesis reproduction. In many cases, the position of is not known, and therefore the upper limit value of θ is also unknown. Therefore, in this embodiment, it is assumed that θ is about 25 degrees to 40 degrees as a common sound source arrangement, and is about 1.5 times the value calculated by {(340/2) / speaker unit interval} [Hz] (≈ A value of about 1 / sin 40 ° to 2.3 times (≈1 / sin 25 °) is set as a wavefront synthesis upper limit frequency for separation by the frequency band separation unit 134.

  The filter coefficient creation unit 136 inputs the standard reproduction condition data included in the metadata extracted by the metadata decoding unit 122 and the actual reproduction condition data sent from the audio output unit 150, and sets the standard reproduction condition as the actual reproduction condition. The filter coefficient of the wavefront synthesis filter for converting to is created.

  The creation of the wavefront synthesis filter coefficient for converting the standard reproduction condition into the actual condition is performed by using the wavefront synthesis filter when the speaker position (position of the array speaker 1) in the standard reproduction of FIGS. The coefficients are calculated based on the concept as shown in FIG. The wavefront synthesis filter coefficient is a method as described in, for example, Takeda et al., “Study on wavefront synthesis using multi-channel speaker reproduction”, pp. 407-408, September 2000. Can be created.

  The high frequency component channel allocation unit 138 receives the analysis result of the frequency analysis unit 132 and the m-channel high frequency band signal separated by the frequency band separation unit 134 and outputs the high frequency band. Allocation and time axis adjustment. The signal output from the high frequency component channel allocation unit 138 is an n-channel signal to match the actual reproduction conditions.

  The wavefront synthesis reproduction signal generation unit 140 receives the wavefront synthesis band signal separated by the frequency band separation unit 134 and the filter coefficient of the wavefront synthesis filter created by the filter coefficient creation unit 136, and performs wavefront synthesis under actual reproduction conditions. It generates a wavefront synthesis signal for performing.

  The wavefront synthesis reproduction signal generation unit 140 generates a wavefront synthesis signal for wavefront synthesis under the actual reproduction conditions using each channel under the standard reproduction conditions as the primary sound source by convolution of each channel signal with the wavefront synthesis filter. The n-channel wavefront synthesis signal generated by the wavefront synthesis reproduction signal generation unit 140 is sent to the signal mixing unit 142.

  The signal mixing unit 142 uses the n-channel wavefront synthesis signal generated by the wavefront synthesis reproduction signal generation unit 140 and the n-channel signal output from the high frequency component channel allocation unit 138 as a speaker unit under actual reproduction conditions. The output is mixed for each channel. In the signal mixing unit 142, the n-channel wavefront synthesis band and the high frequency band are mixed for each channel, thereby generating an n-channel wavefront synthesis reproduction signal under the final actual reproduction condition.

  The configuration of the wavefront synthesis reproduction signal conversion unit 130 according to the embodiment of the present invention has been described above with reference to FIG. By configuring the wavefront synthesis reproduction signal conversion unit 130 in this way, when the content producer differs from the array speaker assumed when the content is created, the wavefront synthesis reproduction signal conversion unit 130 matches the actual environment. Thus, the wavefront synthesized reproduction signal can be converted.

  Note that the processing described above may be executed by providing a storage unit inside the sound field reproduction device and sequentially calling the computer programs stored in the storage unit. Various ROMs (Read Only Memory) may be used as the storage unit.

  As described above, according to the present embodiment, even if the reproduction array speaker at the time of sound case generation is different from the array speaker assumed when the content creator creates the content, By converting the composite playback signal according to the actual environment, it is not necessary to recreate the content from the beginning, and it is possible to divert the content and standardize the content production conditions.

  As mentioned above, although preferred embodiment of this invention was described referring an accompanying drawing, it cannot be overemphasized that this invention is not limited to the example which concerns. It will be apparent to those skilled in the art that various changes and modifications can be made within the scope of the claims, and these are naturally within the technical scope of the present invention. Understood.

  For example, in the above embodiment, the case where sound is output from a linear array speaker has been described, but the present invention is not limited to such an example. Since the wavefront synthesis can be performed with a speaker arrangement other than the linear array speaker, the standard array speaker unit can be used even when the array speaker is converted between an arc shape other than a linear shape, an L shape, and a U shape. As a new primary sound source, the wave front is synthesized by an actual array speaker, and the high frequency component is assigned to the speaker unit in the direction in which the standard array speaker unit can be seen. Even in an environment different from the environment assumed by the above, it is possible to calculate the wavefront synthesized reproduction signal according to the actually used reproducing apparatus and reproduce the synthesized sound field.

1, 1a, 1b Array speaker 2 Standard listening position 10 Sound field reproduction device 110 Data input unit 112 Data decoding unit 114 Demultiplexing unit 120 Audio data decoding unit 122 Metadata decoding unit 130 Wavefront synthesis reproduction signal conversion unit 132 Frequency analysis unit 134 Frequency band separation unit 136 Filter coefficient creation unit 138 Channel allocation unit 140 Wavefront synthesis reproduction signal generation unit 142 Signal mixing unit 150 Audio output unit 152 Amplifier 154 Array speaker 170 Subtitle data decoding unit 172 Subtitle reproduction unit 180 Video data decoding unit 182 Video Playback unit 190 Subtitle superimpose unit 192 Display unit

Claims (5)

A wavefront synthesis reproduction signal input unit for inputting a first wavefront synthesis reproduction signal;
A first wavefront synthesis reproduction condition input unit for inputting a wavefront synthesis reproduction condition including information of speakers constituting an array speaker of the first wavefront synthesis reproduction signal;
A second wavefront synthesis reproduction condition input unit for inputting a wavefront synthesis reproduction condition including information on speakers constituting an array speaker different from the wavefront synthesis reproduction condition;
A wavefront synthesis reproduction signal conversion unit for converting the first wavefront synthesis reproduction signal into a second wavefront synthesis reproduction signal corresponding to the wavefront synthesis reproduction condition input from the second wavefront synthesis reproduction condition input unit;
A wavefront synthesis signal conversion apparatus comprising:   The wavefront synthesized signal conversion apparatus according to claim 1, wherein the information of the speakers constituting the array speaker includes the number of channels of the speakers or the interval of the speaker units.   The wavefront synthesis reproduction signal conversion unit is obtained according to a wavefront synthesis reproduction condition input from the first wavefront synthesis reproduction condition input unit and a wavefront synthesis reproduction condition input from the second wavefront synthesis reproduction condition input unit. The wavefront synthetic | combination signal converter of Claim 1 including the filter part which converts the said 1st wavefront synthetic | combination reproduction | regeneration signal into the said 2nd wavefront synthetic | combination reproduction | regeneration signal using the filter coefficient by which it is performed. The wavefront synthesis reproduction signal converter is
A separation unit that separates the first wavefront synthesized reproduction signal into a high frequency component higher than a predetermined frequency and a low frequency component lower than the predetermined frequency;
An assigning unit that assigns the high frequency component to the high frequency component of the second wavefront synthetic reproduction signal according to the wavefront synthetic reproduction condition input from the second wavefront synthetic reproduction condition input unit;
A low-frequency component conversion unit that converts the low-frequency component into a low-frequency component of the second wavefront synthesis reproduction signal according to the wavefront synthesis reproduction condition input from the second wavefront synthesis reproduction condition input unit When,
A synthesis unit that synthesizes the outputs of the allocation unit and the low frequency component conversion unit to generate the second wavefront synthesis reproduction signal;
The wavefront synthetic | combination signal converter of Claim 1 containing this. Inputting a first wavefront synthesized reproduction signal;
Inputting a wavefront synthesis reproduction condition including information of speakers constituting an array speaker of the first wavefront synthesis reproduction signal;
Inputting a wavefront synthesis reproduction condition including information of speakers constituting an array speaker different from the wavefront synthesis reproduction condition;
Converting the first wavefront synthesis reproduction signal into a second wavefront synthesis reproduction signal corresponding to a wavefront synthesis reproduction condition different from the wavefront synthesis reproduction condition;
A wavefront synthetic signal conversion method comprising:

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