JP6204682B2 - Acoustic signal reproduction device - Google Patents

Description

The present invention relates to audio signal reproducing apparatus of a multi-channel sound system having a plurality of layered sound field.

  In addition to the two-channel and 5.1-channel sound systems currently being produced, multiple sound systems such as the “three-dimensional (three-dimensional) sound system” that exceed the 5.1-channel sound systems such as 7.1 and 22.2 channels are proposed. Has been. The ITU-R, an international standardization organization related to audio, has set requirements (non-patent document 1) for a three-dimensional acoustic system (advanced multichannel audio system) beyond the 5.1 channel acoustic system as an ITU-R recommendation. It is expected that a plurality of acoustic methods will be proposed. By expressing these acoustic systems in a common format, it can be applied to a next-generation audio system and can be a flexible system that can be used in various fields.

"Performance requirements for an advanced multichannel stere ophonic sound system for use with or without accompanying picture", ITU-R recommendation BS. 1909

  As a common format capable of expressing various acoustic systems, “acoustic signals having a single acoustic space layer” are being studied. Here, a sound constructed by a plurality of spatially arranged channel signals is defined as a single acoustic space layer. In conventional program production, all the sounds required for a program are arranged in a single acoustic space layer. Dividing the acoustic space layer that has been integrated into several layers into several layers, producing an audio program, and using the format of "acoustic signal with multiple acoustic space layers", the recipient at the time of program exchange In addition, it is possible to easily transform, convert, and replace the received acoustic signal according to the home environment. Hereinafter, the “multi-channel acoustic system” will be described as intended to be an “acoustic system having a plurality of acoustic spatial layers”.

  For example, a broadcast program broadcast using a multi-channel audio system is produced by various audio systems and reproduced in various reproduction environments. Increasing the number of speakers requires more detailed control of indirect sounds (reverberation components such as reflected sounds). On the other hand, the production environment has a sound environment such as an optimal reverberation time based on a certain standard, but the reproduction environment on the receiving side is not created based on the standard. Depending on the difference between the production environment and the playback environment, the playback sound may differ from the creator's intention.

Accordingly, an object of the present invention made in view of such a point is to provide an acoustic signal reproducing apparatus that can cope with a multi-channel acoustic system having a plurality of acoustic space layers and can adjust an indirect sound in accordance with a reproduction environment. is there.

In order to solve the above-described problems, an acoustic signal reproducing device according to the present invention is a multi-channel acoustic signal reproducing device having a plurality of acoustic spatial layers, including an acoustic spatial layer of at least one indirect sound, The metadata included in the multi-channel sound signal includes the number of sound space layers, the feature values related to the sound of the production environment, a description indicating whether each sound space layer is a direct sound or an indirect sound, and each sound space layer. wherein the arrangement of the sound channel signals, and a respective recommendation loudness indicating the playback balance between layered sound field of the acoustic space layer and the indirect sound of the direct sound, the feature quantity of the production environment and the feature amount of the reproduction environment based on bets, to adjust the volume of the acoustic space layer of the indirect sound so as to realize the characteristic amount close to the production environment when reproducing, layered sound of the acoustic space layer and the indirect sound of the direct sound Comprising a volume adjusting unit for synthesizing.

In addition, when adjusting the volume of the entire multi-channel audio signal, the volume adjustment unit may change the loudness change range from the recommended loudness based on the feature amount of the production environment and the feature amount of the reproduction environment. instead every acoustic space layer, it is preferably synthesized by adjusting the volume of the layered sound field of the acoustic space layer and the indirect sound of the direct sound.

A decoding unit configured to decode a multi-channel acoustic signal, wherein the decoding unit includes a plurality of indirect sound space layers when the multi-channel sound signal includes a plurality of indirect sound space layers; it is preferable to decode only layered sound field differences are minimized indirect sound of the feature quantity of the reproduction environment and the feature quantity of the production environment described the metadata.

Further, the feature quantity of the production environment, the production reverberation time when reproduced by the recommended loudness of each layered sound field in the environment, the interaural cross-correlation, the interaural level difference, and of the interaural time difference It is preferable to include at least one.

According to the audio signal reproducing apparatus according to the present invention, supports multi-channel sound system having a plurality of layered sound field, it is possible to adjust the indirect sound to suit the reproduction environment.

It is a figure which shows the structure of the acoustic signal reproducing | regenerating apparatus which concerns on one Embodiment of this invention. It is a figure which shows an example of the acoustic space layer contained in a multichannel acoustic signal. It is a figure which shows an example of the metadata in a multichannel acoustic signal. It is a figure which shows the structure of the acoustic signal production apparatus which concerns on one Embodiment of this invention.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Here, the present invention corresponds to a multi-channel acoustic signal that is an “acoustic signal having a plurality of acoustic spatial layers”. The applicant has filed a Korean patent application (10-2012-0112984) for “acoustic signals having a single acoustic space layer” and a Japanese patent for “acoustic signals having multiple acoustic space layers”. An application has been filed (Japanese Patent Application 2013-010544).

  FIG. 1 is a diagram showing a configuration of an acoustic signal reproduction device according to an embodiment of the present invention. The acoustic signal reproduction device 10 includes a demultiplexer 11 (DEMUX), a decoding unit 12, a reproduction channel conversion unit 13, and a volume adjustment unit 15. The output signal of the acoustic signal reproduction device 10 is output as sound by the speaker 14. Played.

  The demultiplexer 11 separates the input multi-channel audio data stream into metadata and audio channel signals. The demultiplexer 11 outputs the acoustic channel signal to the decoding unit 12, and outputs the metadata to the decoding unit 12, the volume adjustment unit 15, and the reproduction channel conversion unit 13.

  FIG. 2 is a diagram illustrating an example of an acoustic space layer included in a multi-channel acoustic signal (acoustic data stream) in the present embodiment. The multi-channel acoustic signal in the present embodiment includes a direct sound that directly reaches from a sound source and an indirect sound such as a room reflected sound (reverberation sound) as independent acoustic space layers. The first acoustic space layer 200 is an acoustic space layer made of direct sound, and five channels (210 to 250) are arranged around the user 100. The second acoustic space layer 300 is an acoustic space layer of indirect sound, and five channels (310 to 350) are arranged around the user 100. Note that the multi-channel acoustic signal in the present embodiment includes a plurality of indirect sound space layers, and the indirect sound space layer can be switched according to the reproduction environment feature amount (for example, reverberation time).

  FIG. 3 is a diagram illustrating an example of metadata representing the acoustic space layer illustrated in FIG. 2. The metadata (Sound Essence 000) in FIG. 3 includes the number of acoustic space layers (two layers of direct sound and indirect sound), reverberation time (2 seconds), which is a feature of the production environment, for multi-channel sound signals. The type of multi-channel sound signal (music) is described. Further, in the metadata, the first acoustic space layer 200 (Sound Field 01) that is a direct sound and the second acoustic space layer 300 (Sound Field 02) or the third acoustic space layer 400 (Sound Field 01) that is an indirect sound. Field 03) is linked to form a multi-channel audio signal. Here, the second acoustic space layer 300 and the third acoustic space layer 400, which are indirect sounds, are indirect sounds having different patterns, respectively, and an acoustic signal reproducing device according to the characteristic amount (for example, reverberation time) of the reproduction environment. Is appropriately selected. It is possible to include three or more acoustic space layers as indirect sounds. In addition, the feature quantity in the production environment is not limited to the reverberation time, and other criteria such as the interaural cross-correlation, interaural level difference, and interaural time difference may be used. Can be used as a feature value of the production environment. Moreover, the ratio of a direct sound and an indirect sound is described by each acoustic space layer as recommended loudness as below-mentioned.

  The first acoustic space layer 200 that is a direct sound is composed of 5 channels, the recommended loudness is −18 LKFS, the acoustic channel signal 210 (Channel 01) is Lch, the acoustic channel signal 220 (Channel 02) is Rch, and the acoustic channel. It is described that the signal 230 (Channel 03) is reproduced from Cch, the acoustic channel signal 240 (Channel 04) is reproduced from BLch, and the acoustic channel signal 250 (Channel 05) is reproduced from BRch. Further, the first acoustic space layer 200 describes a direct sound and a link to the second acoustic space layer 300 or the third acoustic space layer 400 that is an indirect sound.

  The second acoustic space layer 300 which is an indirect sound is composed of 5 channels, the recommended loudness is −25 LKFS, the acoustic channel signal 310 (Channel 06) is Lch, the acoustic channel signal 320 (Channel 07) is Rch, and the acoustic channel. It is described that the signal 330 (Channel 08) is reproduced from Cch, the acoustic channel signal 340 (Channel 09) is reproduced from BLch, and the acoustic channel signal 350 (Channel 10) is reproduced from BRch. Further, the second acoustic space layer 300 describes an indirect sound (Reverberation D) and a link to the first acoustic space layer 200 that is a direct sound.

  The third acoustic space layer 400, which is an indirect sound having a pattern different from that of the second acoustic space layer 300, is composed of 5ch, the recommended loudness is -25LKFS, and the acoustic channel signal 410 (Channel 11) is Lch. The acoustic channel signal 420 (Channel 12) is reproduced from Rch, the acoustic channel signal 430 (Channel 13) is reproduced from Cch, the acoustic channel signal 440 (Channel 14) is reproduced from BLch, and the acoustic channel signal 450 (Channel 15) is reproduced from BRch. Have been described. Furthermore, the third acoustic space layer 400 describes an indirect sound (Reverberation W) and a link to the first acoustic space layer 200 that is a direct sound.

  The decoding unit 12 decodes the necessary acoustic channel signal of the acoustic space layer based on the reproduction environment feature quantity stored in advance and the metadata from the demultiplexer 11. More specifically, the decoding unit 12 includes each acoustic channel signal of the first acoustic space layer 200 that is a direct sound, and any of the second acoustic space layer 300 or the third acoustic space layer 400 that is an indirect sound. Each of the acoustic channel signals is decoded. The decoding unit 12 decodes either the second acoustic space layer 300 or the third acoustic space layer 400 as an indirect sound based on the feature amount of the production environment described in the metadata and the feature amount of the reproduction environment. Select whether or not to decrypt. For example, the decoding unit 12 selects and decodes, from the acoustic space layers of the indirect sound, the acoustic space layer from which the reproduced sound closer to the production environment can be obtained when reproduced in the reproduction environment, based on the feature amount of the reproduction environment. Turn into. As a result, it is possible to listen to the reproduced sound closer to the production environment. Needless to say, when there is only one acoustic space layer of the indirect sound, the decoding unit 12 decodes the acoustic space layer of the indirect sound.

  The sound volume adjusting unit 15 is configured to generate an indirect sound space (second sound space layer 300 or third sound space layer 400) based on the feature amount of the production environment described in the metadata and the feature amount of the reproduction environment. ) To be synthesized with the first acoustic space layer 200 of direct sound. For example, when the feature amount of the production environment of the acoustic space layer of the decoded indirect sound is different from the feature amount of the reproduction environment, the volume adjustment unit 15 is based on the feature amount of the production environment and the feature amount of the reproduction environment. The volume of the acoustic space layer of indirect sound is adjusted and synthesized with the acoustic space layer of direct sound. For example, when the reverberation time of the reproduction environment is shorter than the production environment, the volume adjustment unit 15 adjusts the reproduction level of the acoustic space layer of the indirect sound to be larger than the recommended loudness and synthesizes it with the acoustic space layer of the direct sound. To do. This makes it possible to realize a reverberation time that is close to the production environment in a playback environment in which the reverberation time is shorter than the production environment. In other words, even if there is a difference in the playback sound between the production environment and the playback environment, even if you select an acoustic space layer of indirect sound that can reproduce the playback sound close to the production environment, you should listen to the playback sound that is closer to the production environment Is possible. When the feature quantities of the production environment and the reproduction environment match or the difference is within a predetermined allowable range, the volume adjustment unit 15 performs the acoustic space layer of the indirect sound (the second acoustic space layer 300 or the third sound space layer). The acoustic space layer 400) may be directly combined with the first acoustic space layer 200 of direct sound.

  In addition, when adjusting the volume of the entire multi-channel acoustic signal, the volume adjustment unit 15 is configured so that each volume of the first acoustic space layer 200 that is a direct sound is based on the recommended loudness of each acoustic space layer described in the metadata. The volume is adjusted by changing the change width of the loudness of each of the acoustic channel signals and either the second acoustic space layer 300 or the third acoustic space layer 400 that is an indirect sound for each acoustic space layer. be able to. For example, in the case of FIG. 3, when the volume adjustment unit 15 lowers the overall volume from −24 LKFS to −28 LKFS in a reproduction environment with a short reverberation time, the first acoustic space layer 200 (direct sound) is changed from −18 LKFS to −24 LKFS. The second acoustic space layer 300 or the third acoustic space layer 400 (indirect sound) is relatively lowered from -25LKFS to -27LKFS, and the width of the acoustic space layer is reduced. The volume of each acoustic space layer is adjusted according to the role. It becomes possible to listen to the content with playback sound closer to the production environment. Note that, in a playback environment with a long reverberation time, it is possible to adjust the volume more easily to hear by suppressing the indirect sound.

  The reproduction channel conversion unit 13 combines a plurality of acoustic space layers into one acoustic space, and generates an acoustic channel signal to be input to each reproduction speaker in accordance with the reproduction environment.

  As described above, according to the present embodiment, the volume adjustment unit 15 performs the sound of the indirect sound based on the production environment feature amount described in the metadata included in the multi-channel sound signal and the reproduction environment feature amount. The spatial layer is adjusted and synthesized with the direct acoustic space layer. Thus, it is possible to adjust the indirect sound in accordance with the reproduction environment, corresponding to a multi-channel acoustic system having a plurality of acoustic space layers. In particular, by separating and transmitting the sound sections that make up a broadcast program into direct and indirect sounds, it is possible to adjust the reflected sound according to the playback environment and reproduce the sound space as intended by the producer It becomes possible to do.

  The volume adjuster 15 adjusts and synthesizes the volume of the direct sound space and the indirect sound space based on the recommended loudness. If the production environment differs greatly from the playback environment, or if the reverberation time of the playback environment is extremely short, the volume is adjusted so that the playback level is greater than the recommended loudness. Thereby, it becomes possible to listen to the program with a sound quality close to that when listening in the production environment.

  In addition, when the multi-channel acoustic signal includes a plurality of indirect sound space layers, the decoding unit 12 selects the sound of the indirect sound selected based on the production environment feature amount and the reproduction environment feature amount described in the metadata. Perform spatial layer decoding. As a result, the reflected sound can be switched according to the reproduction environment, and the acoustic space as intended by the producer can be reproduced. In addition, since the decoding of the selected indirect sound other than the acoustic space layer can be omitted, it is possible to reduce the processing load related to the decoding.

  The feature amount of the production environment includes at least one of reverberation time, interaural cross-correlation, interaural level difference, and interaural time difference. Accordingly, it is possible to construct a plurality of indirect sound space layers based on various criteria and select an indirect sound space layer more suitable for the reproduction environment, not limited to the reverberation time. That is, the feature amount enables the program to be listened to with an acoustic quality that is closer to the production environment. In addition, although the reverberation time is illustrated in the above description, when the binaural cross-correlation level, the binaural level difference, and the binaural time difference are used as the feature amount of the production environment, the corresponding feature amount is included in the metadata. Needless to say, the acoustic space layer of the indirect sound includes acoustic channel signals prepared according to each feature amount.

  FIG. 4 is a diagram showing a configuration of an acoustic signal creation device according to an embodiment of the present invention. The acoustic signal generation device 20 includes a mixer 21, an encoding unit 22, and a multiplexer 23 (MUX).

  The mixer 21 mixes a plurality of acoustic signals, and outputs them to the encoding unit 22 as acoustic channel signals for each acoustic space layer. Here, the acoustic signal input to the mixer 21 includes acoustic channel signals of the direct sound space layer and the indirect sound space layer.

  The encoding unit 22 encodes the acoustic channel signal of each acoustic space layer from the mixer 21 and outputs it to the multiplexer 23.

  The multiplexer 23 (multiplexing unit) multiplexes the acoustic channel signals of the direct sound space layer and the indirect sound space layer and the metadata including the feature amount of the production environment, such as a program producer. Is multiplexed with the encoded acoustic channel signal to create a multi-channel acoustic signal having a plurality of acoustic spatial layers. Here, the feature quantity of the production environment includes at least one of reverberation time, interaural cross-correlation, interaural level difference, and interaural time difference. The multiplexer 23 can multiplex metadata including recommended loudness of each of the direct sound space and the indirect sound space layer. The multiplexer 23 can multiplex the acoustic channel signals of the acoustic space layer of a plurality of indirect sounds. The multiplexer 23 multiplexes the multi-channel sound signal and transmits it to a remote place such as a home by radio wave or IP line in order to transmit the multi-channel sound signal by broadcasting or transmission.

  As described above, according to the present embodiment, the multiplexer 23 multiplexes the acoustic channel signals of the acoustic space layer of the direct sound and the acoustic space layer of the indirect sound and the metadata including the feature amount of the production environment. As a result, on the acoustic signal reproduction device side, the multi-channel acoustic system having a plurality of acoustic space layers is supported, and the indirect sound can be adjusted according to the reproduction environment. In particular, by separating and transmitting the sound sections that make up a broadcast program into direct and indirect sounds, it is possible to adjust the reflected sound according to the playback environment and reproduce the sound space as intended by the producer It becomes possible to do.

  The multiplexer 23 multiplexes metadata including recommended loudness of each of the direct sound space and the indirect sound space. As a result, it is possible to listen to the program with an acoustic quality closer to the production environment on the acoustic signal reproduction device side.

  Further, the multiplexer 23 multiplexes the acoustic channel signals of the acoustic space layer of a plurality of indirect sounds. Thereby, on the acoustic signal reproduction device side, it is possible to switch the reflected sound in accordance with the reproduction environment, and it is possible to reproduce the acoustic space as intended by the producer.

  The reproduction environment feature amount includes at least one of reverberation time, interaural cross-correlation, interaural level difference, and interaural time difference. As a result, the acoustic signal reproduction device side can select an acoustic space layer of indirect sound that is more suitable for the reproduction environment based on various criteria, without being limited to the reverberation time. That is, the feature amount enables the program to be listened to with an acoustic quality that is closer to the production environment.

  Although the present invention has been described based on the drawings and examples, it should be noted that those skilled in the art can easily make various modifications and corrections based on the present disclosure. Therefore, it should be noted that these variations and modifications are included in the scope of the present invention. For example, functions included in each member, each means, each step, etc. can be rearranged so as not to be logically contradictory, and a plurality of means, steps, etc. can be combined or divided into one. Is possible.

DESCRIPTION OF SYMBOLS 10 Acoustic signal reproduction | regeneration apparatus 11 Demultiplexer 12 Decoding part 13 Reproduction | regeneration channel conversion part 14 Speaker 15 Volume control part 20 Acoustic signal production apparatus 21 Mixer 22 Encoding part 23 Multiplexer (multiplexing part)

Claims (4)

An apparatus for reproducing a multi-channel acoustic signal having a plurality of acoustic spatial layers including an acoustic spatial layer of at least one indirect sound,
The metadata included in the multi-channel sound signal includes the number of sound space layers, the feature amount related to the sound of the production environment, a description indicating whether each sound space layer is a direct sound or an indirect sound, and the sound space layer. Including the placement of each acoustic channel signal and the respective recommended loudness indicating the reproduction balance between the direct sound space space and the indirect sound space layer,
And the feature quantity of the production environment, on the basis of said characteristic quantity of the reproduction environment, to adjust the volume of the acoustic space layer of the indirect sound so as to realize the characteristic amount close to the production environment during playback, the direct An acoustic signal reproduction device comprising a volume adjustment unit that synthesizes an acoustic space layer of sound and an acoustic space layer of the indirect sound . In the acoustic signal reproducing device according to claim 1, when adjusting the volume of the entire multi-channel acoustic signal,
The sound volume adjustment unit is configured to change the change range of the loudness from the recommended loudness for each acoustic space layer based on the feature amount of the production environment and the feature amount of the reproduction environment , so that the acoustic space layer of the direct sound And an acoustic signal reproducing apparatus characterized by adjusting and synthesizing the volume of the acoustic space layer of the indirect sound. The acoustic signal reproduction device according to claim 1 or 2,
A decoding unit for decoding a multi-channel acoustic signal;
Said decoding section, when the multi-channel audio signal includes a plurality of layered sound of the indirect sound of the acoustic space layer of a plurality Included indirect sound, the feature quantity of the production environment described the metadata and the difference between the feature quantity of the reproduction environment, characterized in that decode only acoustic space layer of smallest indirect sound, audio signal reproducing apparatus. In the acoustic signal reproducing device according to any one of claims 1 to 3,
The feature amount of the production environment is at least one of reverberation time, interaural cross-correlation, interaural level difference, and interaural time difference when each acoustic space layer is reproduced with the recommended loudness in the production environment. One characterized in that it comprises a sound signal reproducing apparatus.

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