JP4363924B2 - Audio equipment - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an audio system in which an analog sound signal is digitized, and then is recorded at a proper bit rate according to the sound quality of a sound source with respect to the audio system for digtalizing and recording the analog sound signal. <P>SOLUTION: This audio system is equipped with a plurality of first sound source units 7, 8 each of which outputs a first digital sound source signal obtained from a digital sound source, a plurality of second sound source units 9, 10 each of which outputs an analog sound signal obtained from an analog sound source, a DAC 3 which converts the first digital signal outputted from some of the first sound source units 7, 8, into an analog sound signal, an ADC 12 which converts an analog signal outputted from the DAC 3 or outputted from some of the second sound source units 9, 10 into a second digital sound signal, a coding processing part 11 which applies coding processing to the second digital sound signal and a controller 13 which sets a coding bit rate in the coding processing part 11 based on a table which associates the sound quality of a sound source with the setting value of a coding bit rate. <P>COPYRIGHT: (C)2005,JPO&amp;NCIPI

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an audio apparatus that digitizes an analog audio signal obtained from a sound source and records it on a recording medium.
[0002]
[Prior art]
In recent years, an audio device using a large-capacity recording medium as a recording medium for recording audio data has become widespread. For example, in a car audio apparatus, a CD changer apparatus has been used in order to be able to reproduce a large number of audio data. Currently, a hard disk apparatus is widely used in place of the CD changer apparatus. A vehicle-mounted audio device including a hard disk device usually includes a CD unit, and a user can use a CD (hereinafter simply referred to as “CD”) on which audio data is recorded by a CD-DA (Compact Disc Digital Audio) method. Audio data) can be dubbed to a hard disk. The recording capacity of the hard disk is much larger than the recording capacity of the CD-DA, and the audio data is compressed and recorded on the hard disk. Therefore, many audio data are recorded in the audio device, and the user can select and reproduce desired audio data without carrying many CD-DAs with the audio device.
[0003]
Such an audio device includes an AM tuner, an MD unit, etc. in addition to a CD unit, so that the contents of the received AM radio broadcast can be recorded on a hard disk or recorded on an MD (Mini Disk). Audio data can be played back and recorded on the hard disk. In addition to the CD-DA, the CD unit may be a CD-R or the like (hereinafter referred to as “MP3CD”) in which audio data is recorded by the MP3 (Moving Picture Image Coding Experts Group-1 Audio Layer 3) method or WMA. By supporting a CD-R or the like on which audio data is recorded by the (Windows Media Audio) method, audio data recorded on an MP3 CD or the like can be reproduced and recorded on a hard disk.
[0004]
In audio devices that record audio data as digital data, it is permitted to copy the original audio data recorded on a CD-DA or the like as it is, but the original audio data is used for copyright protection. The so-called second generation audio data, which is a copy of the above, needs to be converted into analog data and then recorded as digital data on a recording medium. Therefore, in the audio apparatus as described above, the audio data recorded on the MD, MP3CD, etc. is once converted into an analog audio signal and then recorded on the hard disk. An analog audio signal output from the AM / FM tuner is digitized by an analog / digital converter and then recorded on a hard disk.
[0005]
[Patent Document 1]
Japanese Patent Laid-Open No. 2003-110448 [Patent Document 2]
JP-A-2002-50121 [0006]
[Problems to be solved by the invention]
In a conventional audio device using a hard disk device, the bit rate when an analog audio signal is digitized and recorded is constant regardless of the sound quality of the sound source. For example, an analog audio signal output from an AM tuner and an analog audio signal obtained by analogizing a digital audio signal output from an MD unit are recorded on a hard disk at the same bit rate after being digitized.
[0007]
However, if the analog audio signal is digitized and recorded at a constant bit rate, the following problem occurs. First, when a relatively high bit rate is set, an analog audio signal obtained from a low sound quality sound source such as an AM radio broadcast is recorded, or audio data recorded in a low sound quality mode on the MD is converted to analog once. When recorded, the amount of data recorded on the hard disk becomes disproportionately large with respect to sound quality. In addition, when a relatively low bit rate is set, once the high-quality sound data recorded on the digital sound source is converted into an analog sound signal and recorded, the sound quality of the sound data recorded on the hard disk deteriorates significantly. End up.
[0008]
The present invention solves the above problem, and in an audio device that digitizes an analog audio signal and records it on a recording medium, after the analog audio signal is digitized, an appropriate bit is selected according to the sound quality of the sound source. An audio device is provided that is recorded on a recording medium at a rate.
[0009]
[Means for Solving the Problems]
The audio apparatus of the present invention inputs an analog audio signal obtained by converting a first digital audio signal obtained from a digital sound source or an analog audio signal obtained from an analog sound source, and the input analog audio signal is used as a second digital audio signal. An audio device that compresses and encodes the second digital audio signal and records it on a recording medium, comprising sound source recognizing means for recognizing a sound source of an input analog sound signal, and recognized by the sound source recognizing means. When the sound source is the first digital audio signal obtained by reading out the audio data stored in the digital sound source, when the analog audio signal converted from the first digital audio signal is digitized and recorded, An encoding bit rate of the second digital audio signal is set according to an audio data recording mode. .
[0010]
The audio device of the present invention further includes sound source recognition means for recognizing the sound source of the input analog audio signal, and the sound source recognized by the sound source recognition means reads out the sound data stored in the digital sound source. When the bit rate of the audio data is variable in the case of the first digital audio signal, the bit rate belongs when the analog audio signal converted from the first digital audio signal is digitized and recorded. An encoding bit rate of the second digital audio signal is set according to a numerical range.
[0011]
Furthermore, in the audio apparatus of the present invention, management information relating to the audio data is read from the digital sound source, and all or part of the management information is recorded on the recording medium together with the second digital audio signal.
[0013]
In the above configuration of the present invention, MD, MP3CD, WMACD or the like is used as the digital sound source, and AM radio broadcast (AM signal) or FM radio broadcast (FM signal) is used as the analog sound source. As the recording medium, a hard disk, DVD-RAM, CD-R, or the like is used. A CD unit, MD unit, or the like is used for the first sound source device, and an AM tuner, FM tuner, or the like is used for the second sound source device. For example, a ROM is used as the storage device, and a microcomputer (hereinafter referred to as “microcomputer”) is used as the control device.
[0014]
[Action and effect]
Depending on the sound quality of the sound source, if the sound source is a digital sound source, further set the encoding bit rate according to the recording mode of the sound data of the digital sound source or the numerical range to which the bit rate of the sound data belongs. Thus, the analog audio signal is digitized and recorded on the recording medium at an appropriate bit rate according to the sound quality of the sound source. Thus, when the sound source has low sound quality, the analog audio signal is not digitized and recorded on the recording medium at an excessive bit rate, and the audio data created on the recording medium by recording the analog audio signal is not recorded. Data volume is reduced. When the sound source has high sound quality, sound data that can be reproduced with high sound quality is created on the recording medium. Further, since the audio data is created on the recording medium in this way, the recording capacity of the recording medium is effectively utilized.
[0015]
Read management information related to audio data, and record the read management information on a recording medium together with the digital audio signal once converted to analog, and then manually input the management information after the recording operation of the audio device is completed. Thus, it is not necessary to record on the recording medium.
[0016]
DETAILED DESCRIPTION OF THE INVENTION
The present invention will be described below with reference to the drawings. FIG. 1 is a block diagram of an audio apparatus according to an embodiment of the present invention. The hard disk device (1) includes a hard disk on which audio data is recorded, a rotation mechanism of the hard disk, a magnetic head for reading / writing audio data from / to the hard disk, a signal processing circuit, and the like (not shown). In this embodiment, MP3 audio data is recorded on the hard disk. When the audio device reproduces audio data recorded on the hard disk, a digital audio signal generated by reading the audio data is output from the hard disk device (1) and sent to the decoding processing unit (2). The digital audio signal is decoded by the decoding processing unit (2) based on the MP3 system, and then converted into an analog audio signal by a digital / analog converter (hereinafter referred to as “DAC”) (3). The The analog audio signal output from the DAC (3) is level-adjusted by the volume (4), amplified by the amplifier (5), and output as audio from the speaker (6).
[0017]
The CD unit (7) includes a drive mechanism for rotating a disk such as CD-DA or MP3CD, an optical pickup mechanism for reading audio data from the disk, a servo control mechanism, a DSP (Digital Signal Processor), a CD-ROM decoder, and the like (not shown). )). A CD such as a CD-DA is detachably attached to the CD unit (7). When an audio device reproduces audio data recorded on a CD-DA, a digital audio signal generated by reading out the audio data is subjected to a CIRC (Cross Interleave Reed-Solomon Code) decoding process and an EFM (Eight) in the DSP. To Fourteen Modulation) After being demodulated, it is sent to the DAC (3) and converted into an analog audio signal. The analog audio signal output from the DAC (3) is output as audio from the speaker (6) via the volume (4) and the amplifier (5).
[0018]
When an audio device reproduces MP3 audio data recorded on an MP3CD, a digital audio signal generated by reading the audio data from the MP3CD is subjected to a CIRC decoding process, an EFM demodulation process, and the like by the DSP. Thereafter, a CD-ROM decoder provided in the CD unit (7) performs a decoding process based on the CD-ROM system. Thereafter, the digital audio signal is sent from the CD-ROM decoder to the decoding processing unit (2), and is decoded based on the MP3 system. Thereafter, the digital audio signal is converted into an analog audio signal by the DAC (3), and then output as audio from the speaker (6) via the volume (4) and the amplifier (5).
[0019]
The MD unit (8) includes a drive mechanism for rotating the MD, an optical pickup mechanism for reading audio data from the MD, a servo control mechanism, a DSP, an ATRAC3 (Adaptive TRansform Acoustic Coding 3) decoder, and the like (not shown). An MD is detachably attached to the MD unit (8). When the audio device reproduces the audio data recorded on the MD, the digital audio signal generated by reading the audio data is subjected to a CIRC decoding process, an EFM demodulation process, etc. in the DSP, and then an ATRAC3 decoder And is subjected to a decoding process based on the ATRAC3 system. Thereafter, the digital audio signal output from the MD unit (8) is converted into an analog audio signal by the DAC (3), and then the audio is output from the speaker (6) through the volume (4) and the amplifier (5). Is output as
[0020]
The audio apparatus can receive AM radio broadcast, and the AM tuner (9) outputs an analog audio signal obtained by demodulating the received AM signal. Further, the audio apparatus can receive FM radio broadcast, and the FM tuner (10) outputs an analog audio signal obtained by performing demodulation processing on the received FM signal. The analog audio signal output from the AM tuner (9) or the FM tuner (10) is output from the speaker (6) via the volume (4) and the amplifier (5).
[0021]
As described above, the audio device according to the present embodiment is recorded on the hard disk of the hard disk device (1), the CD-DA or MP3CD mounted on the CD unit (7), or the MD mounted on the MD unit (8). The reproduced audio data is reproduced, or the received AM radio broadcast or FM radio broadcast sound is output.
[0022]
In addition, the audio apparatus of the present embodiment can record audio data recorded on a CD-DA or MP3CD mounted on the CD unit (7), or audio recorded on an MD mounted on the MD unit (8). Data can be converted to analog once and recorded on the hard disk of the hard disk device (1). Furthermore, the audio apparatus of the present embodiment can digitize the analog audio signal output from the AM tuner (9) or the FM tuner (10) and record it on the hard disk of the hard disk apparatus (1). An analog / digital converter (hereinafter referred to as “ADC”) is connected to a volume (4) to which an analog audio signal output from the DAC (3), AM tuner (9), or FM tuner (10) is input. The ADC (12) converts the analog audio signal output from the volume (4) into a digital audio signal, and the digital audio signal output from the ADC (12) (11) compression encoding processing based on the MP3 system is performed, and the encoding bit rate when the digital audio signal is compression encoded by the encoding processing unit (11) is variable, and the microcomputer (13) The digital audio signal compressed and encoded by the encoding processing unit (11) is sent to the hard disk device (1) and recorded on the hard disk at the same bit rate as the encoding bit rate.
[0023]
The microcomputer (13) performs overall control of the audio device, and the components of the audio device such as the hard disk device (1) and the CD unit (7) are connected via the control bus (14) indicated by the broken line in FIG. And controlled by the microcomputer (13). The microcomputer (13) is connected to a RAM (15) for temporarily storing various data and a ROM (16) in which various control programs are recorded. Further, the microcomputer (13) includes an operation unit (17) including various buttons and switches for a user to operate the audio device, and a display unit (18) including a liquid crystal display device. It is connected. The management information added to the audio data and recorded on the MP3CD, MD, etc. is read out from these, sent to the microcomputer (13), and displayed on the display unit (18). Management information is recorded in an ID3 tag added to audio data in MP3CD, and is recorded in UTOC (User Table Of Contents) in MD.
[0024]
Next, a recording operation using the hard disk device (1) of the audio device of this embodiment will be described. FIG. 2 is a flowchart showing this recording operation. First, when the user operates the operation unit (17) to instruct the microcomputer (13) to start the recording operation, the microcomputer (13) recognizes the sound source that is the target of the recording operation (S1). . The microcomputer (13) recognizes the sound source that is the target of the recording operation by recognizing the activated sound source device or by acquiring information about the sound source from the sound source device. Further, the sound source that is the target of the recording operation may be designated by the operation unit (17) simultaneously with the instruction of the recording operation, and the sound source device related to the sound source may be started up. For example, when the MD is designated as the sound source that is the target of the recording operation, the MD unit (8) is started up.
[0025]
Next, the microcomputer 13 determines whether or not the sound source that is the target of the recording operation is a CD-DA (S2). When the sound source is not a CD-DA, analog recording, that is, recording of an analog audio signal output from the volume (4) is selected (S3). That is, when the sound source is MP3CD or MD, the digital audio signal output from the decoding processing unit (2) or the MD unit (8) is once converted to analog and recorded on the hard disk. When the sound source is AM radio broadcast or FM radio broadcast, an analog audio signal output from the AM tuner (9) or FM tuner (10) is recorded.
[0026]
A bit rate determination table is recorded in the ROM (16). FIG. 3 shows an example of the bit rate determination table. The bit rate determination table is means for associating the sound quality (type) of the sound source with the set value of the encoding bit rate set in the encoding processing unit (11). After step S3, the microcomputer (13) refers to the bit rate determination table, and sets the setting value of the encoding bit rate corresponding to the sound source that is the target of the recording operation in the encoding processing unit (11) ( S4).
[0027]
If the sound source to be recorded is MP3CD, the bit rate information described in the header of the audio data to be recorded (in MP3 format recorded on MP3CD) is read in step S4, and the hard disk It is sent from the device (1) to the microcomputer (13). The audio data is recorded on the MP3 CD based on, for example, the VBR (Variable Bit Rate) method, and the bit rate of the audio data is variable in the VBR method. In the fixed method, the bit rate of the audio data is fixed.
[0028]
As shown in FIG. 3, the bit rate determination table is provided with setting values of the encoding bit rate set in the encoding processing unit (11) corresponding to the three numerical ranges of the bit rate of the audio data. Yes. The microcomputer (13) sets the encoding bit rate of the encoding processing unit (11) to 64 kbps if the bit rate of the audio data is 0 kbps or more and less than 64 kbps, that is, if the sound quality of the audio data is low. If the bit rate of the audio data is 64 kbps or more and less than 108 kbps (if the sound quality of the audio data is medium), the microcomputer (13) sets the encoding bit rate of the encoding processing unit (11) to 108 kbps. If the bit rate of the audio data is 108 kbps or higher (if the sound quality of the audio data is high), the encoding bit rate is set to 132 kbps. In this embodiment, the bit rate of the audio data recorded on the MP3CD is constant for each frame constituting the audio data. In this embodiment, the bit rate of the audio data recorded on the MP3CD is distinguished by three numerical ranges. However, in the present invention, the number of numerical ranges is not particularly limited.
[0029]
When the sound source that is the target of the recording operation is MD, in step S4, recording mode information of audio data, which is one item of UTOC, is sent from the MD unit (8) to the microcomputer (13). In this embodiment, the audio data recorded on the MD is recorded in the normal recording mode (ATARAC Stereo), LP2 mode (ATARAC3 LP2 Stereo), or LP4 mode (ATARAC3 LP4 Stereo). As shown in FIG. 3, the bit rate determination table is provided with a set value of the encoding bit rate set in the encoding processing unit (11) corresponding to each of these three recording modes. The microcomputer (13) refers to the bit rate determination table and sets the encoding bit rate of the encoding processing unit (11) to 132 kbps if the recording mode of the audio data recorded in the MD is the normal recording mode. To do. If the recording mode of the audio data is the LP2 mode, the microcomputer 13 sets the encoding bit rate of the encoding processing unit 11 to 132 kbps, and if the recording mode of the audio data is the LP4 mode, that is, the audio If the sound quality of the data is low, the encoding bit rate is set to 64 kbps.
[0030]
Even if the sound source to be recorded is AM radio broadcast or FM radio broadcast, in step S4, the microcomputer (13) refers to the bit rate determination table and performs encoding in the encoding processing section (11). Set the bit rate. When the sound source is AM radio broadcast, the sound quality of AM radio broadcast is low, so 64 kbps is set in the encoding processing unit (11) as the encoding bit rate. When the sound source is FM radio broadcast, the sound quality of FM radio broadcast is higher than that of AM radio broadcast, so 94 kbps is set in the encoding processing unit (11) as the encoding bit rate.
[0031]
As described above, in step S4, the encoding bit rate corresponding to the sound quality of the sound source that is the target of the recording operation is set in the encoding processing unit (11). Thereafter, the microcomputer (13) determines whether the sound source that is the target of the recording operation records audio data as digital data, that is, whether the sound source that is the target of the recording operation is a digital sound source (S5). . Specifically, it is determined whether the sound source is MP3CD or MD.
[0032]
If the sound source to be recorded is not MP3CD or MD, that is, if it is AM radio broadcast or FM radio broadcast, the analog audio signal output from the AM tuner (9) or FM tuner (10) It is recorded in the device (1) (S6). If it is determined in step S5 that the sound source that is the target of the recording operation is MP3CD or MD, it is determined whether or not the sound source has management information (S7). If the sound source is MD, since MD has UTOC, it is determined in step S7 that it has management information. If the sound source is MP3CD, it is determined in step S7 whether or not the management information is added to the audio data as an ID3 tag. When the management information is not added to the MP3CD audio data, the digital audio signal output from the CD unit (7) and decoded by the decoding processing unit (2) is once converted into an analog signal and then the hard disk device (1 ) Is recorded (S6).
[0033]
When the sound source has management information, the management information is read from the sound source and stored in the RAM (15) (S8). When the sound source is MP3CD and an ID3 tag is added to the audio data, the ID3 tag is read and stored in the RAM (15) via the microcomputer (13). When the sound source is MD, a part of UTOC information (for example, song name) corresponding to the item of ID3 tag is read from the MD and stored in the RAM (15) via the microcomputer (13).
[0034]
After step S8, the digital audio signal output from the CD unit (7) and decoded by the decoding processing unit (2) or the digital audio signal output from the MD unit (8) is once converted into an analog signal. Is recorded on the hard disk (S6). Further, along with the digital audio signal, all or part of the management information is also recorded on the hard disk in the RAM (15). Specifically, when the sound source is MP3CD, the ID3 tag read from the RAM (15) is added to the audio data created on the hard disk by this recording operation. When the sound source is MD, an ID3 tag is created by the microcomputer (13) based on a part of UTOC information stored in the RAM (15), and the created ID3 tag is an audio created on the hard disk. Appended to the data. In a conventional audio apparatus, when audio data of a digital sound source such as MP3CD or MD is once converted to analog and recorded, the management information of the digital sound source is not recorded, and the user records the management information on the hard disk. The work had to be done again. In the audio apparatus of the present invention, since the management information of the digital sound source is automatically recorded on the hard disk in this way, the burden on the user is greatly reduced.
[0035]
If it is determined in step S2 that the sound source to be recorded is a CD-DA, digital recording, that is, a digital audio signal output from the CD unit (7) is input to the encoding processing unit (11). Then, it is selected that the encoding processing unit (11) performs compression encoding and recording it on the hard disk (S9). The bit rate determination table also defines a set value of an encoding bit rate corresponding to the case where CD-DA audio data is digitally recorded. The microcomputer (13) refers to the bit rate determination table and sets 132 kbps as the encoding bit rate of the encoding processing unit (11) (S10). Thereafter, the digital audio signal output from the CD unit (7) is recorded (S6).
[0036]
In the above embodiment, the CD unit (7) is compatible with CD-DA and MP3CD, but the CD unit (7), the decoding processing unit (2), and the encoding processing unit (11) are connected to WMACD or the like. It is also possible to correspond to other sound sources, and further, set values of encoding bit rates corresponding to these sound sources may be added to the bit rate determination table shown in FIG. In the above embodiment, audio signals obtained from various sound sources are recorded on the hard disk. However, the recording medium mounted on the CD unit (7) can be operated by enabling the CD unit (7) to perform the recording operation. An audio signal may be recorded. For example, the digital audio signal output from the MD unit (8) is converted into an analog signal, and further compressed and encoded by the encoding processing unit (11), and recorded on a CD-R or the like attached to the CD unit (7). May be.
[0037]
The above description of the embodiments is for explaining the present invention, and should not be construed as limiting the invention described in the claims or reducing the scope thereof. Each part configuration of the present invention is not limited to the above embodiment, and various modifications can be made within the technical scope described in the claims.
[Brief description of the drawings]
FIG. 1 is a block diagram showing an outline of an audio apparatus according to an embodiment of the present invention.
FIG. 2 is a flowchart showing a recording operation of the audio apparatus according to the embodiment of the present invention.
FIG. 3 is an explanatory diagram showing an example of a bit rate determination table stored in a ROM of the audio apparatus according to the embodiment of the present invention.
[Explanation of symbols]
(3) Digital / analog converter
(7) CD unit
(8) MD unit
(9) AM tuner
(10) FM tuner
(11) Encoding processing unit
(12) Analog / digital converter
(13) Microcomputer
(16) ROM

Claims (3)

An analog audio signal obtained by converting the first digital audio signal obtained from the digital sound source or an analog audio signal obtained from the analog sound source is input, the input analog audio signal is converted into a second digital audio signal, and the second In an audio device that compresses and encodes a digital audio signal and records it on a recording medium,
Sound source recognition means for recognizing the sound source of the input analog sound signal is provided, and the sound source recognized by the sound source recognition means is the first digital sound signal obtained by reading sound data stored in the digital sound source. In this case, when the analog audio signal obtained by converting the first digital audio signal is digitized and recorded, an encoding bit rate of the second digital audio signal is set according to a recording mode of the audio data. An audio device. An analog audio signal obtained by converting the first digital audio signal obtained from the digital sound source or an analog audio signal obtained from the analog sound source is input, the input analog audio signal is converted into a second digital audio signal, and the second In an audio device that compresses and encodes a digital audio signal and records it on a recording medium,
Sound source recognition means for recognizing the sound source of the input analog sound signal is provided, and the sound source recognized by the sound source recognition means is the first digital sound signal obtained by reading sound data stored in the digital sound source. In this case, when the bit rate of the audio data is variable, when the analog audio signal obtained by converting the first digital audio signal is digitized and recorded, the second rate depends on the numerical range to which the bit rate belongs. An audio apparatus characterized by setting an encoding bit rate of a digital audio signal.   The audio apparatus according to claim 1 or 2, wherein management information relating to the audio data is read from the digital sound source, and all or part of the management information is recorded on the recording medium together with the second digital audio signal.

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