Audio system which not only enables the application of the surround system standard to special playback uses but also easily maintains c

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BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to an audio system, its reproducing apparatus, and its recording medium, and more particularly to an audio system that easily maintains compatibility with a surround system when in a system that transmits or records (hereinafter, transmits) surround audio using a plurality of transmission channels, the plurality of channels are used for special purposes, (e.g. such as karaoke), which are not limited to surround, a reproducing apparatus for reproducing audio signals from the system, and a recording medium made according to an allocating method complying with the standard for surround.

2. Description of the Related Art

A conventional surround system, for example, a Dolby surround system AC-3 proposed by Dolby Laboratories, is such that when 5-channel surround audio signals are recorded on a recording medium, such as an optical disk the audio signals are reproduced by a reproducing apparatus compatible with the surround system at three speakers in front of the listener and two speakers behind the same listener. Such conventional systems use this speaker arrangement to form a sound field around the listener giving the feeling of being at a live performance. In addition, the surround system can reproduce audio signals suitable for a 2-channel audio system. The 2-channel audio system converts 5-channel audio signals into 2-channel audio signals using a process known as down-mixing. Based on the 2-channel audio signals, stereo sound is reproduced at the two speakers positioned in front of the listener.

Conventional systems that provide surround reproduction and stereo reproduction of the 5-channel surround audio signals are shown in FIGS. 1A and 1B, respectively. In surround reproduction, 5-channel audio input signals L, C, R, LS, and RS are transmitted to speakers 8L, 8C, 8R, 8LS, and 8RS at the front left, the front center, and the front right, the back left and the back right, respectively, as shown in FIG. 1A. The respective speakers reproduce sound based on the signal input thereto. As described above, in the reproducing system with 5-channel speakers, the sound volume can be adjusted channel by channel. In addition, reproduction can be stopped in any or all channels.

On the other hand, in stereo reproduction, the five input signals L, C, R, LS, and RS undergo down-mixing at a down mixer Dmix. During down-mixing, the input signals are converted into 2-channel audio output signals Lo and Ro, which are then supplied to the front left and front right speakers 8L and 8R: Each of the two speakers 8L and 8R reproduce sound based on the signal input thereto. The down mixer Dmix includes a circuit that down-mixes 5-channel audio input signals L, C, R, LS, and RS as described hereinafter.

The 2-channel audio output signals Lo and Ro, which are obtained by down-mixing and supplied to the front left and front right speakers 8L and 8R, are normally expressed as:

Lo=L+0.7C+0.7LS

Ro=R+0.7C+0.7RS

When 5-channel audio signals are converted into 2-channel audio signals, simple down-mixing may provide unnatural 2-channel reproduction depending on the nature of the 5-channel audio signals. For instance, there may be a case where absence of the surround-channel audio signals LS and RS results in natural reproduction. For this reason, the conventional down mixer Dmix uses a circuit controlled by a control signal Cont to selectively turn on and off the addition of the surround channel audio signals LS and RS, as shown in FIG. 2. To prevent a sense of incongruity from being introduced into the sound field in reproduction, the control signal Cont is not manipulatable by the user. As a rule, the user cannot enter the control signal Cont into the down mixer arbitrarily. Generally, the control signal is determined on the transmission side or the recording side and recorded on an optical disk or a like recording medium. When down-mixing is performed, the audio signals transmitted via a plurality of transmitting channels are reproduced at output channels, where the number of output channels is smaller than the number of transmitting channels. During conventional down-mixing the user cannot change the conversion coefficients including the mixing ratio.

In recent years, in Japan and many other foreign countries, karaoke systems have become very popular, where the user himself or herself sings with background music. Although various karaoke systems have been proposed and those with various functions have been developed, a multi-functional karaoke system that can sufficiently comply with the demands of users has not yet been realized. Similarly, there have been various special demands in systems such as karaoke, for example, when of special reproduction uses, such as a rendering of a particular musical instrument may be reproduced in addition to karaoke.

In systems such as karaoke, to comply with the demands of the users appropriately, it has been necessary to prepare as many audio programs as there are demands and to pre-record data for each audio program on a recording medium. Such systems are problematic since they require a tremendous recording capacity. To reduce memory requirements, a surround sound system has been considered. However, since conventional surround sound systems have not taken into account special applications including karaoke, it is difficult to simply apply such special applications to a surround sound system. Thus, in conventional surround sound systems used for special applications such as karaoke, some improvements are needed. Specifically, when down-mixing is conducted, the audio signals transmitted via a plurality of channels are reproduced at a number of output channels fever than the number of transmission channels. Because the user cannot change the conversion coefficients including the mixing radio once conventional down-mixing is effected, it is necessary to allocate channels, taking into consideration how to handle both those audio signals normally reproduced and those audio signals not normally reproduced. As described above, to provide special applications including karaoke which comply with the various demands of the users, it is necessary to combine a conventional surround sound system with a special system (i.e., a karaoke system) and it is necessary to consider the compatibility between them.

SUMMARY OF THE INVENTION

An object of the present invention is to provide an audio system that easily maintains compatibility with a surround sound system when in a special system that transmits surround audio using a plurality of transmission channels which are used for special uses, such as karaoke, and which are not limited to surround sound. The present invention also has an object to provide a method of reproducing audio signals from the system, a recording medium used with the system, and a method of recording data on the recording medium.

According to the present invention, there is provided an audio system comprising: transmitting means for transmitting one of first and second audio data, the first audio data including a first code information items for determining a surround mode and first and second main audio signals and first sub-audio signal, and second audio data including a second code information items for determining a special-use mode and third and fourth main audio signals and a second sub-audio signal, the fourth main audio signal including a normally available accompanying sound and the second sub-audio signal including one of normally available and normally unavailable accompanying sounds; means for sensing the first and second code information items; means for outputting one of the first and second audio data; and means for allowing the first and second main audio signals or the first and second main audio signals and the first sub-audio signal to output from the outputting means in response to the sensing of the first code information item, and setting the outputting means in a selective setting mode in response to the sensing of the second code information, in which the third main audio signal is outputted from the output means, the fourth main audio signal is normally set in an available mode and is outputted from the output means, and the second sub-audio signal is normally set in an unavailable mode and is prevented from being outputted from the outputting means or the second sub-audio signal is normally set in the available mode and the second sub-audio signal is outputted.

Furthermore, according to the present invention, there is provided an audio system comprising: front left, front center, front right, back left and back right speakers; transmitting means, having front left, front center, front right main audio channels and back left and back right surround audio channels, for transmitting audio information that includes a first and second code information items for determining a surround mode and a special-use mode, and audio data which includes first, second and third main audio contents corresponding to the front left, front center, and front right main audio channels corresponding to the front left, front center, and front right speakers, and first and second sub-audio contents corresponding to surround audio channels corresponding to the back left and back right speakers; means for sensing the first and second code information items; conversion means for, in response to the sensing of the first code information item, converting the first, second and third main audio contents into a first front left, first front center, and first front right main audio signals and the first and second sub-audio contents into a first back left and first back right surround audio signals in the surround mode; and generating means for generating a second front left, second front center, and second front right main audio signals from the first, second and third main audio contents, and generating a second back left and second back right surround audio signals from the first and second sub-audio contents in the special-use mode in response to the sensing of the second code information item, the generating means including means for selectively setting the first, second and third selection modes, and means for allowing second main audio contents to be converted into the second center audio signal as a first type accompanying sound in response to the set of the first selection mode and preventing the second main audio contents from being converted into the second center audio signal in response to no set of first selection mode, and allowing at least one of the first and second sub-audio contents to be converted into first and/or second sub-audio signals as a second type accompanying sound in response to the set of the second mode or third mode, or preventing at least one of the first and second sub-audio contents from being converted into first and/or second sub-audio signals in response to the set of the second mode or third mode.

Furthermore, according to the present invention, there is provided a recording medium comprising: a data area in which an array in which a first and second code information items for determining a surround mode and a special-use mode and audio data corresponding to two or more main audio channel contents and at least one sub-audio channel content have been stored, and type information indicating that the type of the array is of audio data and management information including playback information determining the order in which each unit data item in the array is to be reproduced, have been recorded.

Still furthermore, according to the present invention, there is provided a recording method comprising the steps of: creating an array in which a first and second code information items for determining a surround mode and a special-use mode and audio data corresponding to two or more main audio channel contents and at least one sub-audio channel content have been stored; creating type information indicating that the type of the array is of audio data and management information including playback information determining the order in which each unit data item in the array is to be reproduced; and recording the created first and second code information items, audio data, type information, and management information in a data area on a recording medium.

Still furthermore, according to the present invention, there is provided a method of transmitting and reproducing audio information including first and second code information items for determining a surround mode and a special-use mode and audio data corresponding to two or more main audio channel contents and at least one sub-audio channel content, the audio reproducing method comprising the steps of: sensing the first and second code information items; converting the audio data into two or more main audio signals and at least one sub-audio signal in the surround mode in response to the sensing of the first code information item; converting the audio data into main audio signals and sub-audio signals in the special-use mode in response to the sensing of the second code information item and generating not only a normally available first-type accompanying sound selectively made unavailable, by using at least one of the main audio signals for special use, but also a selectively available second-type accompanying sound normally unavailable by using at least one of the sub-audio signals; and selecting the reproduction of the first- and second-type accompanying sounds.

Still furthermore, according to the present invention, there is provided an audio method of transmitting or recording audio using a plurality of transmission channels, the audio method comprising the steps of: providing a surround mode and a special mode; transmitting a flag signal indicating one of the modes; providing two or more front channels that transmit audio signals to be outputted from front speakers and one or more surround channels that transmit surround signals in the surround mode; and transmitting main signals via at least one of the front channels, transmitting a selectively unavailable first accompanying sound via at least one of the rest of the front channels, and transmitting a second accompanying sound selectively used or selectively made unavailable via at least one of the surround channels, in the special mode.

Still furthermore, according to the present invention, there is provided an audio method comprising the steps of: providing a maximum of five transmission channels; determining front channels to be channels that transmit a left audio signal and a right audio signal to be outputted from a front left speaker and a front right speaker, respectively, and a central audio signal to be outputted from a front center speaker, and determining surround channels to be channels that transmit a left surround audio signal and right surround audio signal to be outputted from a back left speaker and a back right speaker, respectively, in a surround mode; and transmitting main signals via the channels that transmit the left audio signal and right audio signal, transmitting a selectively unused first accompanying sound via the channel that transmits the central audio signal, and transmitting a selectively used second accompanying sound using the surround channel, in the special mode.

With the multichannel audio system of the present invention, in addition to main audio data items and sub-audio data items that are divided into a plurality of channels on a recording medium, data indicating whether the audio data items are for use in the surround mode or for special use, such as karaoke, are written on the recording medium. The description of the mode, together with the audio data, is transmitted to the reproduction side where surround reproduction is carried out in the surround mode on the basis of the surround standard.

When the audio data is for special use, a normally used first-type accompanying sound selectively made unused is generated by using at least one of the main audio signals for special use, and a second-type accompanying sound for which whether it is selectively used and normally unused or selectively unused and normally used has been specified, is generated by using at least one of the sub-audio signals. As a result, it is possible to reproduce the transmitted audio data according to the choice the user has selected. Additionally, the first- and second-type accompanying sounds can be selected by the user. According to the selection, the audio data items can be mixed. Consequently, in the special-use mode, it is possible to reproduce audio in various representation forms according to the demands of the user.

Additional objects and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention, or may be realized and obtained by means of the instrumentalities and combinations particularly pointed out in the appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate presently preferred embodiments of the invention and, together with the general description given above and the detailed description of the preferred embodiments given below, serve to explain the principles of the invention.

FIG. 1A is a block diagram of a conventional surround system;

FIG. 1B is a block diagram of an example of down-mixing in a conventional surround system;

FIG. 2 is a block diagram to help explain down-mixing in a conventional system;

FIG. 3 is a functional block diagram of a reproduction route that realizes a surround playback mode and a special-use playback mode according to an embodiment of the present invention;

FIG. 4 is a block diagram showing the schematic construction of an optical disk apparatus according to one embodiment of this invention;

FIG. 5 is a perspective view schematically showing the structure of an optical disk to be loaded on the disk drive section shown in FIG. 4;

FIG. 6 is a block diagram showing in detail the mechanism portion of a disk drive section shown in FIG. 4;

FIG. 7 shows the structure of a logic format of an optical disk associated with an improved one of the initial version of the logic format of the optical disk of FIG. 5;

FIG. 8 shows the structure of the video manager of FIG. 7;

FIG. 9 shows an example of the structure of the video object set (VOBS) of FIG. 8;

FIG. 10 shows the parameters in the volume manager information management table (VMGI.sub.-- MAT) in the video manger (VMG) of FIG. 7 and the description thereof;

FIG. 11 shows the structure of the title search pointer table (TT.sub.-- SRPT) in the video manger information (VMGI) of FIG. 8;

FIG. 12 shows the parameters for title search pointer table information (TT.sub.-- SRPT1) in the title search pointer table (TT.sub.-- SRPT) of FIG. 11;

FIG. 13 shows the parameters for the title search pointers (TT.sub.-- SRP) corresponding to the entry numbers of the title search pointer table (TT.sub.-- SRPT) of FIG. 11 and the description thereof;

FIG. 14 is an explanatory diagram to help explain the structure of a program chain stored in a file;

FIG. 15 shows the structure of a video manager menu PGCI unit table (VMGM.sub.-- PGCI.sub.-- UT) shown in FIG. 8;

FIG. 16 shows the contents and parameters of the VMGM.sub.-- PGCI unit table information shown in FIG. 15;

FIG. 17 shows the contents and parameters of video manager menu language unit search pointer shown in FIG. 15;

FIG. 18 shows the structure of a video manager menu language unit shown in FIG. 15;

FIG. 19 shows the contents and parameters of video manager menu language unit information shown in FIG. 18;

FIG. 20 shows the contents and parameters of video manager menu program chain information shown in FIG. 18;

FIG. 21 shows the structure of a video title set attribute table shown in FIG. 8;

FIG. 22 shows the contents and parameters of video title set attribute table information shown in FIG. 21;

FIG. 23 shows the contents and parameters of video title set attribute search pointer shown in FIG. 21;

FIG. 24 shows the contents and parameters of video title set attribute shown in FIG. 21;

FIG. 25 shows the structure of the video title set shown in FIG. 7;

FIG. 26 shows the parameters in the video title set information management table (VTSI.sub.-- MAT) for the video title set information (VTSI) of FIG. 25 and the description thereof;

FIG. 27 is a bit map table of the audio stream attributes (VTS.sub.-- AST.sub.-- ATR) described in the table (VTSI.sub.-- MAT) of FIG. 26;

FIG. 28 shows the structure of the video title set program chain information table (VTS.sub.-- PGCIT) of FIG. 25;

FIG. 29 shows the parameters for pieces of information (VTS.sub.-- PGCITI) in the video title set program chain information table (VTS.sub.-- PGCIT) of FIG. 28 and the description thereof;

FIG. 30 shows the parameters for search pointers (VTS.sub.-- PGCIT.sub.-- SRP) of the video title set program chain information table (VTS.sub.-- PGCIT) of FIG. 28 and the description thereof;

FIG. 31 shows the structure of the program chain information (VTS.sub.-- PGCI) for the video title set corresponding to a program chain in the video title set program chain information table (VTS.sub.-- PGCIT) of FIG. 28;

FIG. 32 shows the parameters for pieces of general information (PGC.sub.-- GI) on a program chain in the program chain information (VTS.sub.-- PGCI) of FIG. 31;

FIG. 33 shows the structure of a program chain map (PGC.sub.-- PGMAP) in the program chain information (VTS.sub.-- PGCI) of FIG. 31;

FIG. 34 shows the parameters for the entry cell numbers (ECELLN) of the programs written in the program chain map (PGC.sub.-- PGMAP) of FIG. 33 and the description thereof;

FIG. 35 shows the structure of a cell playback information table (C.sub.-- PBIT) in the program chain information (VTS.sub.-- PGCI) of FIG. 31;

FIG. 36 shows the parameters for pieces of cell playback information (C.sub.-- PBI) in the cell playback information table (C.sub.-- PBIT) of FIG. 35 and the description thereof;

FIG. 37 shows the structure of cell position information (C.sub.-- POSI) in the program chain information (VTS.sub.-- PGCI) of FIG. 31;

FIG. 38 shows the parameters for the cell position information (C.sub.-- POSI) of FIG. 37 and the description thereof;

FIG. 39 shows the structure of a video title set menu PGC unit table shown in FIG. 25;

FIG. 40 shows the contents and parameters of video title set PGCI unit table information shown in FIG. 39;

FIG. 41 shows the contents and parameters of a video title set language search pointer shown in FIG. 39;

FIG. 42 shows the structure of a video title set language unit shown in FIG. 39;

FIG. 43 shows the contents and parameters of video title set menu language unit information shown in FIG. 42;

FIG. 44 shows the contents and parameters of a video title set PGCI search pointer shown in FIG. 42;

FIG. 45 shows the structure of the navigation pack of FIG. 9;

FIG. 46 shows the structure of the video, audio, or sub-picture pack of FIG. 9;

FIG. 47 shows the parameters for presentation control information (PCI) in the navigation pack of FIG. 45 and the description thereof;

FIG. 48 shows the parameters for general information (PCI.sub.-- GI) in the presentation control information (PCI) of FIG. 47 and the description thereof;

FIG. 49 shows the parameters for disk search information (DSI) in the navigation pack of FIG. 45 and the description thereof;

FIG. 50 shows the parameters for DSI general information (DSI.sub.-- GI) in the disk search information (DSI) of FIG. 49 and the description thereof;

FIG. 51 shows the parameters for synchronous playback information (SYNCI) on the video object (VOB) OF FIG. 50 and the description thereof;

FIG. 52 is an explanatory diagram of the structure of an audio stream acting as audio data in a music file;

FIG. 53 is a conceptual diagram to help explain the structure of an audio pack shown in FIG. 52;

FIG. 54 is a conceptual diagram of the structure of audio data shown in FIG. 53;

FIG. 55 is a conceptual diagram of the structure of frame data shown in FIG. 54;

FIG. 56 shows the description of audio coding mode in the bit stream information of FIG. 55;

FIG. 57 is a flowchart for illustrating the retrieving operation of the video manager menu;

FIG. 58 shows an example of the video manager menu;

FIG. 59 is a flowchart for illustrating the retrieving operation of the video title set menu;

FIG. 60 shows an example of the video title set menu;

FIG. 61 shows another example of the video title set menu;

FIG. 62 is a flowchart for illustrating the selecting operation of the audio stream and sub-picture stream;

FIGS. 63A and 63B show examples of the mode information appearing on the display unit of FIG. 3;

FIG. 64 is a block diagram of the surround mixing coefficient generator of FIG. 3 with a pictorial representation of the down-mixer's function;

FIG. 65 is a block diagram of the special-use mixing coefficient generator of FIG. 3 with a pictorial representation of the down-mixer's function;

FIG. 66 shows an example of applying the circuit function of FIG. 65 to a duet karaoke system;

FIG. 67 shows an example of applying the circuit function of FIG. 65 to a surround karaoke system;

FIG. 68 shows an example of applying the circuit function of FIG. 65 to a surround 5-channel karaoke system;

FIG. 69 shows an example of changing of mixing coefficients in the circuit function of FIG. 65;

FIG. 70 shows examples of the coefficients shown in FIG. 69;

FIG. 71 is a block diagram of an encoder system that creates video files by encoding the video data;

FIG. 72 is a flowchart for the encoding process of FIG. 66;

FIG. 73 is a flowchart for combining the main video data, audio data, and sub-picture data that have been encoded in the flow of FIG. 72 and creating a video data file;

FIG. 74 is a block diagram of a disk formatter system used to record a formatted video file on an optical disk;

FIG. 75 is a flowchart for creating logic data to be recorded on the disk in the disk formatter of FIG. 69; and

FIG. 76 is a flowchart for creating from logic data physical data to be recorded on the disk.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Hereinafter, referring to the accompanying drawings, embodiments of an audio system of the present invention, its reproducing method, its recording medium, and a method of recording data on its recording medium will be explained.

FIG. 3 is a functional block diagram of a reproducing system where a special use function, such as karaoke, is added to a surround system according to an embodiment of the present invention.

The reproducing system of FIG. 3 constitutes part of an optical disk system that reproduces data from an optical disk 10, or other recording medium, as shown in FIG. 4. The system of FIG. 3 corresponds to a part of an audio decoder section 60 and a part of a D/A and reproducing section 64 in FIG. 4. The circuit of the reproducing system of FIG. 3 is constructed by, for example, using a Dolby surround system AC-3 proposed by Dolby Laboratories. Recorded on the optical disk 10 serving as a recording medium are: audio data in which 5-channel audio signals are encoded, bit stream information data indicating the attributes of the audio data, among other data as will be explained later. The audio data and bit stream information data are inputted as audio stream signals as shown in FIG. 3. The audio data in the audio stream signals are decoded at a decoder section 60 and outputted to a down mixer 161.

The bit stream information data in the inputted audio stream signal is supplied to a mode sensor 163, which judges whether the mode is a surround mode or a special playback mode, such (as karaoke as described later). If it is the surround mode, the audio data will not be subjected to a down-mixing process at the down mixer 161, but will instead be converted into analog audio signals by a D/A converter that are outputted in the form of the corresponding 5-channel audio signals L, C, R, LS, and RS. The audio signals L, C, R, LS, and RS are amplified at an amplifier (not shown). The amplifier supplies the amplified signals to 5-channel speakers 8L, 8C, 8R, 8LS, and 8RS, respectively, which perform surround reproduction. Even in the surround mode, when the reproduction is provided with only two 2-channel speakers 8L and 8R, a signal indicating a 2-channel system is entered from an input section 164 into a control circuit 168. Upon receipt of such a signal, control circuit 168 supplies a default mixing signal indicating that a down-mixing process should be carried, and that the down-mixing process should not be based on coefficients generated by a special-use mixing coefficient generator 165 but that it should be based on coefficients generated by a surround mixing coefficient generator 167 via an inverter 166. In response to the default mixing signal, the special-use mixing coefficient generator 165 is disabled and the surround mixing coefficient signal generator 167 is enabled.

Moreover, when a signal indicating a 2-channel system is entered from an input section 164, the control circuit 168 supplies to the surround mixing coefficient generator 167 a control signal related to a first specific mixing coefficient predetermined on the transmission side and written in a bit stream information data. In response the surround mixing coefficient generator 167 supplies to the down mixer 161 a first mixing signal corresponding to a predetermined mixing ratio. Thus, the down mixer 161 effects the default mixing of the 5-channel audio signals and outputs the following 2-channel audio output signals Lo and Ro, which are supplied to a front left speaker 8L and a front right speaker 8R, respectively:

Lo=L+0.7C+0.7LS

Ro=R+0.7C+0.7RS

In the case of a sound source that provides a sense of incongruity after such a down-mixing process, the bit stream information data is sensed at the mode sensor 163. In response to the sense signal from the mode sensor 163, the control circuit 163 supplies to the surround mixing coefficient generator 167 a bit signal related to a second specific mixing coefficient written in the bit stream information data together with the default mixing signal. In response to the bit signal related to the second mixing coefficient, the surround mixing c