JP4549100B2 - CD-TEXT playback device and CD-TEXT processing circuit - Google Patents

Description

  The present invention relates to a CD-TEXT playback device and a CD-TEXT processing circuit.

  In an optical disc playback system for playing back an optical disc conforming to the CD standard, various displays based on information played back from the optical disc are performed. For example, in the CD standard in general, track number, time information assigned to each track number, etc. based on Q channel data (hereinafter referred to as sub Q data) among sub code information recorded in the lead-in area. The sub-code information is recorded in the lead-in area as sub-Q data. Therefore, in the optical disc reproducing system, various displays can be made by reading out the sub-Q data from the lead-in area and decoding / reproducing it.

  Further, a CD-TEXT standard has been proposed for recording TEXT information such as album titles and song titles on an optical disc by adding them to audio information. In the CD-TEXT standard, TEXT information exists for a maximum of 8 blocks depending on the language, and one block exists for a maximum of 255 packs. One pack as a minimum unit is composed of 18 bytes, of which 2 bytes are a CRC (Cyclic Redundancy Check) code. In the CD-TEXT standard, the TEXT information in the above-described format is recorded as R to W channel data (hereinafter referred to as sub R to W data) in the subcode information in the lead-in area. Therefore, in an optical disc playback system (hereinafter referred to as a CD-TEXT playback device) compliant with the CD-TEXT standard, the display of TEXT information is performed by reading and decoding / playing sub R to W data from the lead-in area. Can be made.

  FIG. 14 is a diagram showing a configuration of a conventional CD-TEXT playback device (for example, see Patent Document 1 shown below).

  The optical pickup 301 reads out information recorded on the optical disc 100 by emitting laser light to the optical disc 100 and detecting its return light. The preamplifier 302 generates an RF signal by amplifying the light detection signal detected by the optical pickup 301 with a predetermined amplification factor. The preamplifier 302 performs binarization so as to convert the RF signal, which is an analog signal, into a binary digital signal. The EFM demodulator 303 performs EFM (Eight to Fourteen Modulation) demodulation on the binarized RF signal generated by the preamplifier 302. The signal subjected to the EFM demodulation is transmitted to the subcode decoder 304.

  The subcode decoder 304 decodes subcode information. Of the decoded subcode information, the sub P and Q data are transmitted to the microcomputer 306 and stored in the RAM 307, and the sub R to W data are transmitted to the CD-TEXT decoder 305. The subcode decoder 304 performs CRC based on the CRC code included in the sub-Q data, and detects whether the decoding result of the sub-Q data is normal. The CRC result is transmitted to the microcomputer 306 and stored in the RAM 307 before the sub Q data is transmitted.

  Therefore, the microcomputer 306 acquires the sub-Q data from the sub-code decoder 304 when the CRC result of the sub-Q data transmitted from the sub-code decoder 304 is normal. The microcomputer 306 analyzes TOC (Table Of Contents) information based on the sub-Q data acquired from the sub-code decoder 304, and acquires position information on the optical disc 100 on which a desired music program is recorded. .

  The CD-TEXT decoder 305 decodes TEXT information according to the CD-TEXT standard based on the sub R to W data transmitted from the sub code decoder 304. Further, every time TEXT information is decoded, the CD-TEXT decoder 305 performs CRC based on the CRC code included in the TEXT information, and determines whether or not the decoding result of the TEXT information is normal. Then, 1 bit indicating the CRC result (eg, “1” when normal, “0” when not normal) is first transmitted to the microcomputer 306 and stored in the RAM 307.

When the 1-bit CRC result transmitted from the CD-TEXT decoder 305 is normal, the microcomputer 306 obtains 16-byte TEXT data (ID1 that is 1 byte each) as a decoding result of the TEXT information from the CD-TEXT decoder 305. ~ 4 and 12-byte TEXT content). The microcomputer 306 performs display reproduction of the TEXT content corresponding to the TEXT data acquired from the CD-TEXT decoder 305 while synchronizing with reproduction of a desired music program based on the analysis result of the TOC information. .
JP 2003-36650 A

  In the conventional CD-TEXT playback apparatus as shown in FIG. 14, it is necessary to consider the procedure for acquiring a 1-bit CRC result and determining the CRC result until the microcomputer acquires 16-byte TEXT data. is there. This is a factor that increases the processing load on the microcomputer, and further causes a delay in optical disc playback processing such as display of TEXT information decoded by the CD-TEXT decoder and audio output.

The main present invention for solving the above-mentioned problems is composed of four identifiers , each of which is 1 byte, based on R to W channel data of subcode information read from the lead-in area of a CD standard optical disc. And decoding the TEXT information including a plurality of packs of one pack composed of header information, TEXT content, and error detection code according to the CD-TEXT standard, and the error included in the one pack A CD-TEXT decoder for detecting an error in the decoded TEXT information based on a detection code; and a microcomputer for displaying and reproducing the decoded TEXT content when the error detection result is normal. in CD-TEXT playback apparatus, the CD-TEXT decoder is included in the pack A TEXT data register storing a first data set composed of the decoded header information and TEXT content, and the four identifiers included in the decoded header information for the first data set By masking all 7 bits except for the most significant bit of the identifier of the second byte that can set any of the track numbers from “1” to “99” in decimal notation, by “1”, An error determination identification code generation circuit that generates a second data set that is an identification code indicating that the error detection result is not normal, and when the error detection result is normal, from the TEXT data register transmitting the first data set in the microcomputer, when the error detection result is not normal, the error determination identification Sending from the code generating circuit said second data set to said microcomputer, said microcomputer, when receiving the first data set, the first with the error detection result is identified to be a normal It is assumed that when the second data set is received by displaying and reproducing the TEXT content included in this data set, it is identified that the error detection result is not normal.

In another aspect of the present invention for solving the above-mentioned problems, subcode information R to W read from the lead-in area of the optical disk connected to a microcomputer that controls the entire reproduction process of the CD standard optical disk. Based on the channel data, each pack is composed of one pack composed of header information, TEXT content, and error detection code according to the CD-TEXT standard composed of four identifiers of 1 byte each. In the CD-TEXT processing circuit for performing decoding of the TEXT information and detecting the error of the decoded TEXT information based on the error detection code included in the one pack, the decoded information included in the one pack In the microcomputer composed of header information and TEXT content A TEXT data register storing a first data set for display and reproduction, and, for the first data set, out of the four identifiers included in the decoded header information, “ By masking all 7 bits except for the most significant bit of the identifier of the second byte capable of setting any one of the track numbers from “1” to “99” with “1”, the error detection result in the microcomputer has a an error determining identification code generating circuit for generating a second data set is an identification code for identifying the fact not normal, when the error detection result is normal, the from the TEXT data register outputting a first data set, if the error detection result is not normal, the from the error determining identification code generating circuit Outputting the second data set, and to.

  According to the present invention, it is possible to increase the speed of optical disc playback processing.

<CD standard in general>
FIG. 6 shows the physical format of the optical disc 100 in conformity with the CD standard (CD-DA, CD-ROM, CD-R, CD ± RW, etc.). In the optical disc 100, from the inner periphery toward the outer periphery, a lead-in area 11 in which TOC information is recorded, a program area 12 in which program data such as audio information is recorded, and a lead-out area that indicates the end of program recording Region 13 is formed.

  By the way, when audio information is recorded on the optical disc 100, first, the audio information is sampled under the sampling condition of the sampling frequency of 44.1 kHz and the quantization bit number of 16 bits. The sampled 16-bit audio information is divided into upper / lower 8 bits and each is handled as one symbol. Then, CIRC (Cross Interleave Reed-Solomon Code) encoding processing and interleaving processing are performed for every 24 symbols corresponding to 6 samples of the stereo L / R channel. As a result, 4 symbols of P parity and Q parity are added to form one frame for a total of 32 symbols. Each symbol in one frame is subjected to EFM modulation processing and converted from 8 bits to 14 bits.

  FIG. 7 shows the data structure of one frame (hereinafter, 1 EFM frame) after EFM modulation. As shown in FIG. 7, one EFM frame is composed of a synchronization pattern area of 24 channel bits, a subcode area of 14 channel bits, and a program and parity data area for 32 symbols × 14 channel bits. Also, 3 channel bits are arranged to combine the areas, that is, one EFM frame is constituted by a total of 588 bits.

  FIG. 8 shows the data structure of one subcoding frame. One subcoding frame is configured by collecting 98 EFM frames shown in FIG. As shown in FIG. 8, one sub-coding frame includes a frame synchronization pattern, a sub-code part, and a data and parity part. One subcoding frame corresponds to 1/75 second (13.3 milliseconds) of the reproduction time.

  FIG. 9 shows the data structure of the subcode part in one subcoding frame shown in FIG. As shown in FIG. 9, the first frames 01 and 02 are synchronization patterns S0 and S1 of one sub-coding frame. The synchronization patterns S0 and S1 are two predetermined patterns that are out of the standard in the EFM conversion method. Further, each of the frames 03 to 98 constitutes P, Q, R, S, T, U, V, and W channel data (hereinafter referred to as sub P to W data).

  The sub-P data represents a silent part (PAUSE) between programs, and is provided for rough cueing when searching for programs. The sub-Q data includes information such as absolute time information on the optical disc 100, time information of each program, program identification number, and the like, and is used as TOC information recorded in the lead-in area 11.

  FIG. 10 shows the data structure of sub-Q data and TOC information. The sub-Q data includes 4-bit control data for identifying the number of audio channels, emphasis, 4-bit address data indicating the sub-Q data mode, 72-bit data, and CRC for the sub-Q data. CRC code.

  When the address data of the sub Q data is “1”, the 72-bit data includes the movement number TNO, the index X, the elapsed time (MIN, SEC, FRAME) in the movement, all zeros, the absolute time (AMIN, ASEC, AFRAME) format. This format is associated as TOC information. In other words, the TOC information is composed of the movement number TNO, POINT, the elapsed time (MIN, SEC, FRAME) in the movement, and the absolute time of the POINT content, and has a data length of 72 bits in total. Note that TOC information indicating the same contents is repeatedly recorded in the lead-in area 11 for re-reading when an error is detected in the TOC information.

<CD-TEXT standard>
The CD-TEXT standard is for recording TEXT information such as a title, a performer, a songwriter, a composer, an arranger, and a message on a music CD. It is a standard and can handle up to 8 languages. In the CD-TEXT standard, TEXT information is configured using sub-code information for six channels from sub R to W data, and is recorded in the lead-in area 11.

  FIG. 11 shows an outline of the CD-TEXT standard. In the lead-in area 11, recording is performed in units of TEXT groups corresponding to one language. One TEXT group includes a maximum of 8 blocks, and each block includes packs 0 to n (a maximum of 255 packs). Here, one pack is the minimum unit of TEXT information in the CD-TEXT standard. As shown in FIG. 12, one pack is composed of a total of 18 bytes including 4-byte ID1 to ID4, 12-byte TEXT content, and 2-byte CRC code. Further, as shown in FIG. 13, in one block in one TEXT group, one packet composed of four packs is recorded in synchronization with the synchronization patterns S0 and S1 having a period of 1/75 second. Is set.

  Note that 4-byte ID1 to ID4 are header information of one pack. ID1 is an identification code indicating the type of TEXT information recorded in one pack. For example, album name / program name, performer, songwriter, composer, etc. In ID2, track numbers from “1” to “99” are recorded. The MSB (most significant 1 bit) of ID2 is a reserved area and is always “0”. ID3 is a sequence number assigned to the pack. For example, the sequence number of a pack in one block is “0” to “255”. ID4 consists of 1-bit DBCC (Double Byte Character Code), 3-bit block number, and 4 bits indicating the character position.

  The 2-byte CRC code is an error detection code for a total of 16 bytes of header information of ID1 to ID4 and TEXT information. In the CD-TEXT standard format, when a data error is detected by CRC, the error correction is not performed and the sub-R to W data is read again from the lead-in area 11.

<Configuration of CD-TEXT playback device>
FIG. 1 is a diagram showing a configuration of a CD-TEXT playback apparatus according to an embodiment of the present invention. Note that the CD-TEXT playback apparatus according to the present invention is compatible with the CD-DA standard related to playback of audio information, particularly the CD-TEXT standard included in the CD-DA standard. Of course, an optical disk recording / reproducing system compatible with the CD-R standard, the CD-RW standard, and the like related to optical disk recording may be used.

  The optical pickup 101 includes a laser element, an objective lens, a photodetector, and a servo mechanism (all not shown), and emits laser light to the optical disc 100 and detects its return light. Thus, the information recorded on the optical disc 100 is read out.

  The preamplifier 102 generates an RF signal by amplifying a signal detected by the optical pickup 101 with a predetermined amplification factor. In the preamplifier 102, binarization is performed to convert an RF signal, which is an analog signal, into a binary digital signal. Further, the preamplifier 102 generates a servo control signal such as a tracking error signal or a focus error signal and transmits it to the servo signal processing unit 104.

  The EFM demodulator 103 performs EFM demodulation on the binarized RF signal generated by the preamplifier 102. The signal subjected to EFM demodulation is transmitted to a CIRC error correction unit (Cross Interleave Reed Solomon) 107 in the case of audio information, and is transmitted to the subcode decoder 109 in the case of subcode information. The binarized RF signal generated by the preamplifier 102 is transmitted to a PLL circuit (not shown) to generate a bit clock signal.

  The servo signal processing unit 104 controls driving of various servo mechanisms included in the optical pickup 101 via the driver 105 based on the servo control signal transmitted from the preamplifier 102 and the bit clock signal described above, and the spindle motor 106. Drive control is performed.

  The CIRC error correction unit 107 performs error correction based on the C1 sequence and C2 sequence Reed-Solomon codes according to the CIRC method on the EFM demodulated signal related to the audio information transmitted from the EFM demodulation unit 103. . Here, the digital audio signal is decoded as a result of error correction in the CIRC error correction unit 107. The decoded digital audio signal is converted into an analog audio signal by the D / A converter 108 and output to the outside via the Lch and Rch terminals.

  The subcode decoder 109 decodes subcode information composed of sub P to W data recorded in the lead-in area 11 of the optical disc 100. Of the decoded subcode information, sub P and Q data are transmitted to the microcomputer 111 and sub R to W data are transmitted to the CD-TEXT decoder 110. The subcode decoder 109 performs CRC based on the CRC code included in the sub-Q data detected within 1/75 second, and determines whether the decoding result of the sub-Q data is normal. The CRC result is transmitted to the microcomputer 111 before the sub-Q data is transmitted. Therefore, the microcomputer 111 acquires the sub Q data from the sub code decoder 109 when the CRC result of the sub Q data is normal.

  A CD-TEXT decoder (“CD-TEXT processing circuit”) 110 decodes TEXT information in accordance with the CD-TEXT standard based on the sub R to W data transmitted from the sub code decoder 109. Further, every time the TEXT information is decoded, CRC is performed based on the CRC code included in the TEXT information to detect whether the decoding result of the TEXT information is normal. The CRC result of the TEXT information is used to determine whether or not the TEXT information is recorded on the optical disc 100.

  In addition, when the CRC result is normal, the CD-TEXT decoder 110 has a total of 16 bytes of TEXT data (“first data set” composed of the decoded 4-byte ID1 to ID4 and the 12-byte TEXT contents. ]) Is generated and transmitted to the microcomputer 111. On the other hand, when the CRC result is not normal, the error determination identification code (“second data set”) is the same data size as the 16-byte TEXT data, that is, the identification code indicating that the CRC result is not normal. ) And transmitted to the microcomputer 111.

  The microcomputer 111 controls the entire CD-TEXT playback apparatus. For example, the microcomputer 111 analyzes the TOC information based on the sub-Q data transmitted from the sub-code decoder 109 to display the TEXT information decoded from the optical disc 100, and the desired music program is recorded. Position information on the optical disc 100 is acquired. Then, servo control of the optical pickup 101 is performed based on this position information, and a desired music program is read and reproduced.

  Further, when the TEXT information is recorded on the optical disc 100, the microcomputer 111 performs the following display and reproduction of the TEXT information corresponding to the desired music program while synchronizing with the reproduction of the desired music program. Process.

  That is, when the microcomputer 111 receives 16-byte TEXT data from the CD-TEXT decoder 110, the microcomputer 111 identifies that the CRC result of the TEXT data is normal, and the TEXT content included in the TEXT data Display processing is performed and output to an external display device. On the other hand, when the microcomputer 111 receives the 16-byte error determination identification code from the CD-TEXT decoder 110, the microcomputer 111 identifies that the CRC result of the TEXT data is not normal, and reads the subcode information from the lead-in area 11. A predetermined error processing such as re-reading is performed.

  The preamplifier 102 and the driver 105 described above are normally implemented as a CD analog signal processing circuit, and include an EFM demodulation unit 103, a servo signal processing unit 104, a CIRC error correction unit 107, a D / A converter 108, and a subcode. The decoder 109 and the CD-TEXT decoder 110 are usually implemented as a CD digital signal processing circuit. The CD-TEXT processing circuit according to the present invention is implemented as the CD-TEXT decoder 110.

<Configuration of CD-TEXT Decoder>
FIG. 2 is a block diagram showing a configuration of the CD-TEXT decoder 110 according to the embodiment of the present invention.

  As a feature of the CD-TEXT decoder 110 according to the present invention, when the CRC result of the TEXT data is normal, the normal TEXT data for one pack is transmitted to the microcomputer 111, and the CRC result of the TEXT data is If not normal, an error determination identification code is transmitted to the microcomputer 111.

  Here, the error determination identification code is composed of 4-byte header information changed to contents outside the CD-TEXT standard and decoded 12-byte TEXT contents. That is, even if the CRC result is not normal, the error determination identification code has the same data structure as that of one pack of TEXT data when the CRC result is normal. As a result, a mechanism for generating an error determination identification code and a mechanism for transmitting the error determination identification code to the microcomputer 111 are efficiently realized by diverting the mechanism of an existing CD-TEXT playback device. can do.

  As the error determination identification code adopted by the CD-TEXT decoder 110 shown in FIG. 2, any of track numbers from “1” to “99” in decimal notation can be set as shown in FIG. The header information in which ID2 in the second byte is changed from any one of “100” to “127” in decimal notation to binary notation is changed to contents outside the CD-TEXT standard.

  In the example shown in FIG. 2, in order to simplify the configuration of the CD-TEXT decoder 110 and to divert the existing specification of the microcomputer 111, ID2 in the error determination identification code is assigned to the most significant MSB (specification In the above, it is assumed that all 7 bits except “0”) are all set to “1”. That is, ID2 in the error determination identification code is “01111111” in binary notation and “7Fh” in hexadecimal notation, as shown in FIG. Hereinafter, the configuration of the CD-TEXT decoder 110 in this case will be described.

  The 1-pack detection / CRC processing unit 200 receives sub-R to W data sequentially transmitted in units of 1 packet (4 packs) based on the synchronization patterns S0 and S1 having a period of 1/75 second from the sub-code decoder 109. The sub R to W data for one pack is detected, and the TEXT data for one pack is decoded from the sub R to W data for one pack. The decoded TEXT data for one pack is sequentially stored in the TEXT data register 201. Note that one pack of TEXT data stored in the TEXT data register 201 is composed of 4 bytes of header information ID1 to ID4 excluding the CRC code and 12 bytes of TEXT content.

  The 1-pack detection / CRC processing unit 200 performs CRC based on the CRC code included in the decoded PACK data for one pack, and sequentially stores the CRC result in the CRC result register 202. The CRC result indicates, for example, “1” when the error detection based on the CRC method is normal and normal, and “0” when the error detection is not normal.

  The difference code register 203 is a register that stores a 16-byte difference code for generating a 16-byte error determination identification code. As shown in FIG. 4, the ID code for error determination is “7Fh” in hexadecimal notation as shown in FIG. 4, so the header part that is the upper 4 bytes of the difference code is “007F0000”. The remaining 12 bytes of the difference code are all “0”.

  The OR element 204 performs an OR operation between the 16-byte TEXT data stored in the TEXT data register 201 and the 16-byte difference code stored in the difference code register 203. As a result, the output of the OR element 240 is a 16-byte error determination identification code in which ID2 is changed to “7Fh” in hexadecimal notation. That is, as a result of adopting ID2 in the error determination identification code in which all 7 bits excluding the most significant MSB are set to “1”, the error determination identification is performed by a simple mechanism such as an OR operation in the OR element 204. Code can be generated.

  The multiplexer 205 receives the 16-byte TEXT data stored in the TEXT data register 201 and the error determination identification code that is the output of the OR element 204. The multiplexer 205 is supplied with the CRC result stored in the CRC result register 202 as a control signal for selecting two input data. Here, when the CRC result supplied from the CRC result register 202 is “1” indicating normality, normal 16-byte TEXT data is selected. On the other hand, when the CRC result supplied from the CRC result register 202 is “0” indicating that the CRC result is not normal, an error determination identification code is selected. Then, one of the TEXT data selected by the multiplexer 205 or the error determination identification code is transmitted to the microcomputer 111.

<Operation of CD-TEXT playback device>
The operation of the CD-TEXT playback apparatus according to the embodiment of the present invention will be described based on the flowchart shown in FIG. It is assumed that the microcomputer 111 has already acquired the sub-Q data decoded by the sub-code decoder 109 and has completed the TOC analysis.

  First, the microcomputer 111 performs servo control of the optical pickup 101 on the servo signal processing unit 104 in order to read the subcode information recorded in the lead-in area 11 of the optical disc 100 in order to decode the TEXT information. Make it work. As a result, the subcode information is read from the lead-in area 11, amplified by the preamplifier 102, EFM demodulated by the EFM demodulator 103, and transmitted to the subcode decoder 109. Then, the subcode decoder 109 decodes the subcode information after EFM demodulation. At this time, sub-R data in units of 1 packet (4 packs) is sequentially transmitted from the sub-code decoder 109 to the CD-TEXT decoder 110 based on the synchronization patterns S0 and S1 having a period of 1/75 second. .

  In CD-TEXT decoder 110, one pack detection / CRC processing unit 200 detects sub-R to W data for one pack, and TEXT data for one pack from the sub-R to W data for one pack. Is decoded (S500). The decoded TEXT data for one pack is sequentially stored in the TEXT data register 201. The TEXT data stored in the TEXT data register 201 is supplied to the multiplexer 205, and an error determination identification code is supplied to the multiplexer 205 by a logical sum with the difference code stored in the difference code register 203.

  The 1-pack detection / CRC processing unit 200 performs CRC based on the CRC code included in the decoded 1-pack TEXT data, and the CRC result is sequentially stored in the CRC result register 202 (S501). .

  The CD-TEXT decoder 110 selects, in the multiplexer 205, either TEXT data or an error determination identification code based on the CRC result stored in the CRC result register 202 and transmits it to the microcomputer 111. More specifically, in the case of “1” indicating that the CRC result is normal (S502: YES), TEXT data is selected (S503), and in the case of “0” indicating that the CRC result is not normal (S503: YES) In S502: NO), an error determination identification code is selected (S504). Then, one of the TEXT data selected by the multiplexer 205 or the error determination identification code is transmitted to the microcomputer 111.

  The microcomputer 111 receives TEXT data or an error determination identification code from the CD-TEXT decoder 110. When the microcomputer 111 receives the TEXT data, the microcomputer 111 identifies that the CRC result of the TEXT data is normal, and performs a display process of the TEXT information corresponding to the TEXT data. When an error determination identification code is received, it is identified that the CRC result of the TEXT data is not normal, and a predetermined error process is performed.

<Examples of effects>
In the conventional case as shown in FIG. 14, in the CD-TEXT playback device, it is necessary to consider the procedure for acquiring / determining the 1-bit CRC result until the microcomputer acquires 16-byte TEXT data. On the other hand, in the case of the present invention, the step for acquiring / determining the CRC result and the step for acquiring TEXT data are not performed independently and sequentially, but from the CD-TEXT decoder 110 to the microcomputer 111. The microcomputer 111 can simultaneously acquire / determine the CRC result and acquire the TEXT content in one transmission / reception procedure of the TEXT data or the error determination identification code. As a result, an increase in the processing load on the microcomputer 111 is suppressed, and the speed of optical disc playback processing such as display of TEXT information decoded by the CD-TEXT decoder 110 and audio output can be increased.

<Other embodiments>
Although the present embodiment has been described above, the above-described examples are for facilitating the understanding of the present invention, and are not intended to limit the present invention. The present invention can be changed / improved without departing from the spirit thereof, and the present invention includes equivalents thereof.

  In the embodiment described above, ID2 in the error determination identification code is “7Fh” in hexadecimal notation, but is not limited to this. For example, although the content of the specification change of the microcomputer 111 increases, all the bits of ID2 including the MSB in the error determination identification code may be all set to “1”. In this case, ID2 in the error determination identification code is “FFh” in hexadecimal notation.

  Alternatively, all the bits of the header part of the upper 4 bytes in the error determination identification code may be all “1”. In this case, the header part of the upper 4 bytes in the error determination identification code is “FFFFFFFFh” in hexadecimal notation. If the CRC result is not normal, the 12-byte TEXT content included in the error determination identification code is not used in the microcomputer 111, and therefore all the bits of the 12-byte TEXT content may be set to “1”.

It is a figure which shows the structure of the CD-TEXT reproduction | regeneration apparatus concerning one Embodiment of this invention. It is a figure which shows the structure of the CD-TEXT decoder which concerns on one Embodiment of this invention. It is a figure which shows the structure of the TEXT data for 1 packet transmitted to the microcomputer from the CD-TEXT decoder which concerns on one Embodiment of this invention. It is a figure which shows the difference code which concerns on one Embodiment of this invention. It is a flowchart which shows the flow of the optical disk reproduction | regeneration processing based on one Embodiment of this invention. It is a figure which shows the physical format of an optical disk. It is a figure which shows the data structure of 1 EFM frame. It is a figure which shows the data structure of 1 subcoding frame. It is a figure which shows the data structure of the subcode part in 1 subcoding frame. It is a figure which shows the data structure of Q channel data and TOC data. It is a figure which shows the outline of CD-TEXT standard. It is a figure which shows the data structure of 1 pack. It is a figure which shows the format of TEXT information in 1 block. It is a figure which shows the structure of the conventional CD-TEXT reproduction | regeneration apparatus.

Explanation of symbols

11 Lead-in area 12 Program area 13 Lead-out area 100 Optical disc 101, 301 Optical pickup 102, 302 Preamplifier 103, 303 EFM demodulator 104 Servo signal processor 105 Driver 106 Spindle motor 107 CIRC error corrector 108 D / A converter 109 , 304 Subcode decoder 110, 305 CD-TEXT decoder 111, 306 Microcomputer 200 1 pack detection / CRC processing unit 201 TEXT data register 202 CRC result register 204 OR element 205 Multiplexer 307 RAM

Claims (2)

Based on the R to W channel data of the subcode information read from the lead-in area of the CD standard optical disc, header information and TEXT contents according to the CD-TEXT standard composed of four identifiers each having 1 byte. And decoding TEXT information configured by having a plurality of packs of one pack composed of error detection codes, and errors in the decoded TEXT information based on the error detection codes included in the one pack In a CD-TEXT playback apparatus comprising: a CD-TEXT decoder that performs detection; and a microcomputer that displays and reproduces the decoded TEXT content when the error detection result is normal.
The CD-TEXT decoder
A TEXT data register storing a first data set composed of the decoded header information and TEXT content included in the one pack;
Of the four identifiers included in the decoded header information, two bytes that can set any of the track numbers from “1” to “99” in decimal notation for the first data set An error determination identification code for generating a second data set, which is an identification code indicating that the error detection result is not normal, by masking all 7 bits except the most significant bit of the eye identifier with “1” A generation circuit;
Have
If the error detection result is normal, send the first data set from the TEXT data register to the microcomputer;
If the error detection result is not normal, the second data set is transmitted from the error determination identification code generation circuit to the microcomputer;
The microcomputer is
When the first data set is received, the error detection result is identified as normal and the TEXT content included in the first data set is displayed and reproduced.
Identifying that the error detection result is not normal when the second data set is received;
CD-TEXT playback apparatus characterized by the above. It is connected to a microcomputer that controls the entire playback process of a CD standard optical disc, and is composed of four identifiers that are 1 byte each based on R to W channel data of subcode information read from the lead-in area of the optical disc. The TEXT information included in the one pack is decoded while the header information, the TEXT content, and the error detection code are included in one pack. In a CD-TEXT processing circuit that performs error detection of the decoded TEXT information based on an error detection code,
A TEXT data register storing a first data set for display and reproduction in the microcomputer, which is constituted by the decoded header information and TEXT content included in the one pack;
Of the four identifiers included in the decoded header information, two bytes that can set any of the track numbers from “1” to “99” in decimal notation for the first data set A second data set which is an identification code for identifying that the error detection result is not normal in the microcomputer by masking all 7 bits except the most significant bit of the eye identifier with “1”. An error determination identification code generation circuit to be generated;
Have
If the error detection result is normal, output the first data set from the TEXT data register;
If the error detection result is not normal, outputting the second data set from the error determination identification code generation circuit;
C D-TEXT processing circuit characterized.

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