CN1404058A - EFM data decoding method for CD machine system - Google Patents
EFM data decoding method for CD machine system Download PDFInfo
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- CN1404058A CN1404058A CN 02147195 CN02147195A CN1404058A CN 1404058 A CN1404058 A CN 1404058A CN 02147195 CN02147195 CN 02147195 CN 02147195 A CN02147195 A CN 02147195A CN 1404058 A CN1404058 A CN 1404058A
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Abstract
The EFM data decoding method in CD machine system includes the following steps: inputting serial data; taking out from the serial data 14 bits of data to be EFM decoded; looking up the corrected EFM decoding table to convert the 14 bits of data into 8 bits of data; and outputting the 8 bits of data. The corrected EFM decoding table has data of converting 14 bits data not conforming the EFM modulation rules to 8 bits data, and may be used to convert the 14 bits data not conforming the EFM modulation rules to most possible 8 bits data. The present invention can raise data read reliability.
Description
Technical field
Interpretation method when the present invention relates to a kind of data of optical disk and reading, and when being particularly related to a kind of CD of reading CD (Compact Disk), the wherein methods of the data decoding of 8 to 14 modulation (Eight to Fourteen Modulation is called for short EFM).
Background technology
In order to adapt to the characteristic of CD, and the reliability when increasing data of optical disk and reading, data storing can be carried out EFM and Reed-Soloman sign indicating number modulation treatment when CD, and upsets the order of data storing in intersection (Interleave) mode.Therefore, if will be when the CD optical disk reading is fetched data, data must be earlier through the EFM data decoding.Please refer to Fig. 1, what it illustrated is part reading flow journey synoptic diagram in compact disc read-only memory (hereinafter to be referred as the CD-ROM) CD, wherein, data signals EFM DATA and time pulse signal EFM CLK that the rf data that is got by induction laser (Radio Frequency Data is called for short RF DATA) process data shaping circuit 100 produces numeral export 8 bit data then after EFM decoding unit 102 is deciphered conversion.And C1 decoding unit 104 receives 32 8 bit data continuously and (promptly after 32 * 8=256bits), it is decoded into 28 8 bit data.After then de-cross unit 106 is separated intersection to these 8 bit data of 28, again it is reached C2 decoding unit 108.
Because storage data is during to the CD CD, when running into the burning state that changes when data are 1 in the present CD, and when running into the burning state that does not change when data are 0 in the present CD.And so-called EFM processing is 8 data-switching to be become 14 data, and the data after handling through EFM are stored in the CD again.These data of 14 after EFM handles have a primitive rule, make the identical burning state duration that is stored in the CD be no less than 3 EFM CLK cycle, also make identical burning state duration be not more than the cycle of 11 EFM CLK simultaneously.That is to say that the signal waveform of EFM DATA can not change in the cycle of 3 EFM CLK, and the signal waveform of EFM DATA (comprises) in the cycle of 11 EFMCLK and must change.With the viewpoint of 14 bit data, two contiguous data are that data are that 0 number can not occur being less than 2 in 1, also can not occur greater than 10.
Because the speed that present CD reads is more and more high, easily read CD with 40 times of speed or the reading rate that surpasses 40 times of speed, add the characteristic of easy scratch of CD or the like, make in the process of CD CD read-outing data, occur not meeting 14 bit data of above-mentioned EFM modulating rule easily,, give the subsequent demodulation resume module without leave if there is not suitable EFM data decoding to dispose, will make the fiduciary level of data read reduce, choose sheet or can not read problem such as data even produce.
Summary of the invention
The invention provides a kind of method that applies to the EFM data decoding of optical disk drive system, can handle 14 bit data that do not meet the EFM modulating rule especially, improve the fiduciary level of data read, and avoid choosing sheet or can not read problems such as data.
For realizing above-mentioned and other purpose, the invention provides a kind of method that applies to the EFM data decoding of optical disk drive system, comprise the following steps: at first input serial data, for example read serial data from CD; Then from serial data, take out 14 bit data of waiting for EFM decoding; From revise the EFM decoding table, table look-up then, change 8 bit data after this 14 bit data becomes decoding; Export this 8 bit data at last.Wherein, the most special being in when revising the EFM decoding table and have 14 to 8 translation data that do not meet the EFM modulating rule, the 14 bit data decoding that also these can not met the EFM modulating rule converts most probable 8 bit data to.And these do not meet 14 to 8 translation data of EFM modulating rule, belong to 14 bit data parts of the input of tabling look-up, and are that data are that 0 number is less than 2 in 1 in two contiguous data; Or be that data are 0 number greater than 10 situation in 1 in two contiguous data.
The present invention also provides a kind of method that applies to the EFM data decoding of optical disk drive system, comprises the following steps: at first input serial data; Then from serial data, take out 14 bit data of waiting for EFM decoding; Judge then whether this 14 bit data meets the EFM modulating rule, when not meeting the EFM modulating rule, adjusting this 14 bit data becomes most probable 14 bit data; From the EFM decoding table, table look-up again, to change 8 bit data after this 14 bit data becomes decoding; And export this 8 bit data at last.Wherein the most special be in, for example: when 14 bit data are that data are 0 number when being less than 2 in 1 in two contiguous data, adjusting then that this 14 bit data becomes in its two contiguous data is that data are that 0 number equals 2 in 1; Or when 14 bit data are that data are 0 number during greater than 10 in 1 in two contiguous data, adjusting then that this 14 bit data becomes in its two contiguous data is that data are that 0 number equals 10 in 1.
Because special 14 bit data that do not meet the EFM modulating rule of handling of the present invention, it is replaced with most probable 14 bit data, do the EFM decoding again or directly export most probable 8 bit data, make follow-up C1 decoding module be obtained more the multidata processing that continues, thereby improve the fiduciary level of data read, and avoid choosing sheet or can not read problem such as data.
Description of drawings
For above and other objects of the present invention, feature and advantage can be become apparent, a preferred embodiment cited below particularly, and be described with reference to the accompanying drawings.
Fig. 1 shows part reading flow journey synoptic diagram in a kind of CD-ROM CD.
Fig. 2 shows that 14 bit data of waiting for EFM decoding may produce the waveform synoptic diagram of the example that does not meet the EFM modulating rule.
Fig. 3 illustrates the process flow diagram of method that applies to the EFM data decoding of optical disk drive system according to a preferred embodiment of the present invention a kind of.
The process flow diagram of the method for Fig. 4 illustrates according to the present invention another preferred embodiment a kind of EFM data decoding that applies to optical disk drive system.
The drawing reference numeral explanation
100: the data shaping circuit
The 102:EFM decoding unit
The 104:C1 decoding unit
106: de-cross unit
The 108:C2 decoding unit
S310, S410: input serial data
S320, S420: the data of taking out 14
S330: the transcoding of from the EFM decoding table of having revised, tabling look-up
S340, S460: export 8 data
S430: judge whether to meet the EFM modulating rule
S440: the transcoding of from the EFM decoding table, tabling look-up
Embodiment
Fig. 2 may produce the waveform synoptic diagram of the example that does not meet the EFM modulating rule for showing 14 bit data of waiting for EFM decoding, please refer to Fig. 2.The 14 bit data EFM DATA that attempt correct wait EFM decoding are example, and this EFM DATA=14 ' h1220 wherein 14 ' represent 14, and h represents 16 carry representations (following expression is also same), as representing with 2 carries:
EFM DATA=0001,0010,0010, the waveform that 00b then as correctly reads this EFM DATA is as shown in Figure 2.But owing to read CD with high reading rate, or CD factor such as scratch just, may obtain as shown in Figure 2 EFMDATAE1 or two kinds of waveforms of EFM DATAE2, because the same burning state of these two kinds of waveforms is kept the cycle less than 3 EFM CLK, therefore these two kinds of waveforms do not meet the EFM modulating rule, EFMDATAE1 is that falling edge is done sth. in advance transition in this example, delays transition and EFM DATAE2 is a rising edge.This two 14 bit data is expressed as:
EFM?DATAE1＝0001，0100，0010，00b＝14’h1420
EFM?DATAE2＝0000，1010，0010，00b＝14’h0A20
Observe these two 14 bit data that do not meet the EFM modulating rule, it is that data are that 0 number has only 1 in 1 in two contiguous data, be less than at least 2 of EFM modulating rule, if adjust that this two 14 bit data becomes in its two contiguous data is that data are that 0 number equals 2 in 1, and make EFM DATAE1 and EFM DATAE2 become most probable 14 bit data EFM DATA, just but this two 14 bit data of transcoding is correct 8 bit data output, another kind of embodiment is directly to revise the EFM decoding table, with EFM DATAE1 and two kinds of data that do not meet 14 bit data of EFM modulating rule as the input of tabling look-up of EFM DATAE2, just can obtain and 8 identical bit data of EFM DATA input, so, when making follow-up C1 decoding module obtain the processing that continues of how possible correct data.In fact, though on data processing backward, still can come debug by ECC (Error Correction Code) and EDC (ErrorDetection Code), but because of the present invention is after data transfer digital kenel to by simulation, carry out the preliminary correction of data immediately, so when data do not meet the EFM modulating rule, just directly replace with " most probable " EFM data.With thinking in the other direction, be exactly unfortunate conjecture mistake, also, can't influence the correctness of reading with original not coming to the same thing of conjecture.
Those skilled in the art can in like manner push away it, when 14 bit data that do not meet the EFM modulating rule, it is that data are that 0 number is during greater than 10 in 1 in two contiguous data, adjusting then that this 14 bit data becomes in its two contiguous data is that data are that 0 number equals 10 in 1, and replaces with most probable 14 bit data.
Fig. 3 illustrates the process flow diagram of method that applies to the EFM data decoding of optical disk drive system according to a preferred embodiment of the present invention a kind of.Please refer to Fig. 3, describe the method for a kind of EFM data decoding provided by the present invention in detail.At first execution in step S310 is exactly an input serial data, for example: induction from the laser of CD reflection and RF DATA, and read the numeric string line data that this RF DATA produces through data shaping circuit.Then execution in step S320 is exactly from serial data, takes out 14 bit data of waiting for EFM decoding, for example, when reading CD-ROM, this serial data comprises 33 group of 14 bit data, these the 1st group of 14 bit data is the control code data, takes out remaining 32 group of 14 bit data then in regular turn.
Carry out the specific step S330 of the present invention then, from revise the EFM decoding table, table look-up, change 8 bit data after this 14 bit data becomes decoding.Last execution in step S340 exports 8 bit data after this decoding.By the explanation of above-mentioned Fig. 2 as can be known,, this has 14 to 8 translation data that do not meet the EFM modulating rule, so can convert the 14 bit data decoding that does not meet the EFM modulating rule to the most approaching 8 correct bit data equally because having revised the EFM decoding table.For example: this does not meet in 14 to 8 translation data of EFM modulating rule, belongs to 14 bit data parts of the input of tabling look-up, and is that data are that 0 number is less than 2 in 1 in two contiguous data; Or this does not meet 14 to 8 translation data of EFM modulating rule, and it belongs to 14 bit data parts of the input of tabling look-up, and is that data are that 0 number is greater than 10 in 1 in two contiguous data.Table one is the some of the EFM decoding table of having revised, and wherein 14 bit data of representing with bracket are the data that do not meet the EFM modulating rule.
Table one
| 14 bit data | 8 bit data | 14 bit data | 8 bit data |
| ????(14′h1420) | ????0 | ????14′h1220 | ????0 |
| ????14′h2100 | ????1 | ||
| ????(14′h2820) | ????2 | ????14′h2420 | ????2 |
| ????14′h2220 | ????3 | ????14′h1100 | ????4 |
| ????14′h0110 | ????5 | ????14′h0420 | ????6 |
| ????(14′h0A00) | ????7 | ????14′h0900 | ????7 |
| ????(14′h1140) | ????8 | ????(14′h1280) | ????8 |
| ????(14′h0A40) | ????8 | ????(14′h1440) | ????8 |
| ????14′h1240 | ????8 |
The process flow diagram of the method for Fig. 4 illustrates according to the present invention another preferred embodiment a kind of EFM data decoding that applies to optical disk drive system, it comprises the following steps: at first execution in step S410, is exactly input serial data; Then execution in step S420 is exactly from serial data, takes out 14 bit data of waiting for EFM decoding; Execution in step S430 judges whether this 14 bit data meets the EFM modulating rule then, execution in step S440 when not meeting the EFM modulating rule, and adjusting this 14 bit data becomes most probable 14 bit data; Execution in step S450 tables look-up from the EFM decoding table again, to change 8 bit data after this 14 bit data becomes decoding; And last execution in step S460, export this 8 bit data.
In the method for the other a kind of EFM data decoding that provides of the invention described above the most special be in: when not meeting the EFM modulating rule, adjusting earlier this 14 bit data becomes most probable 14 bit data and tables look-up.For example: when 14 bit data are that data are 0 number when being less than 2 in 1 in two contiguous data, adjusting then that this 14 bit data becomes in its two contiguous data is that data are that 0 number equals 2 in 1; Or when 14 bit data are that data are 0 number during greater than 10 in 1 in two contiguous data, adjusting then that this 14 bit data becomes in its two contiguous data is that data are that 0 number equals 10 in 1.
Because special 14 bit data that do not meet the EFM modulating rule of handling of the present invention, it is replaced with most probable 14 bit data, do the EFM decoding again, or directly export most probable 8 bit data, make follow-up C1 decoding module be obtained more the multidata processing that continues, thereby improve the fiduciary level of data read, and avoid choosing sheet or can not read problem such as data.
Though the present invention discloses as above with a preferred embodiment; right its is not in order to qualification the present invention, those skilled in the art, under the premise without departing from the spirit and scope of the present invention; can be used for a variety of modifications and variations, so protection scope of the present invention is as the criterion with the scope of claim.
Claims (10)
1. a method that applies to the EFM data decoding of optical disk drive system comprises the following steps:
The input serial datum;
From this serial data, take out first data of utilizing first bit format to encode;
From a correction EFM decoding table, table look-up, become second data of utilizing second bit format coding to change these first data; And
Export this second data;
Wherein, this correction EFM decoding table has the format conversion data that do not meet the EFM modulating rule, so that each first data is able to one of corresponding second data.
2. the method for EFM data decoding as claimed in claim 1, wherein this first bit format coding is to encode with 14, and this second bit format coding is to encode with 8.
3. the method for EFM data decoding as claimed in claim 2 does not wherein meet the format conversion data of this EFM modulating rule, and it belongs to 14 bit data parts of the input of tabling look-up, and is that data are that 0 number is less than 2 in 1 in two contiguous data.
4. the method for EFM data decoding as claimed in claim 2 does not wherein meet these 14 to 8 translation data of this EFM modulating rule, and it belongs to 14 bit data parts of the input of tabling look-up, and is that data are that 0 number is greater than 10 in 1 in two contiguous data.
5. the method for EFM data decoding as claimed in claim 1, wherein this optical system is the optical system that can read compact disc read-only memory (CD-ROM).
6. a method that applies to the EFM data decode of optical disk drive system comprises the following steps:
The input serial datum;
From this serial data, take out first data of utilizing first bit format to encode;
When these first data do not meet the EFM modulating rule, adjust this first data, so that these first data are met this EFM modulating rule;
From an EFM decoding table, table look-up, become second data of utilizing second bit format coding to change these first data; And
Export this second data.
7. the method for EFM data decoding as claimed in claim 6, wherein this first bit format coding is to encode with 14, and second bit format coding is to encode with 8
8. the method for EFM data decoding as claimed in claim 7, wherein this 14 bit data does not meet this EFM modulating rule and is meant that it is that data are that 0 number equals 2 in 1 that this 14 bit data is become in its two contiguous data, or the format conversion data of this EFM modulating rule, it belongs to 14 bit data parts of the input of tabling look-up, and is that data are that 0 number is less than 2 in 1 in two contiguous data.
9. the method for EFM data decoding as claimed in claim 7 does not wherein meet these 14 to 8 translation data of EFM modulating rule, and it belongs to 14 bit data parts of the input of tabling look-up, and is that data are that 0 number is greater than 10 in 1 in two contiguous data.
10. the method for EFM data decoding as claimed in claim 6, wherein this optical system is the optical system that can read compact disc read-only memory (CD-ROM).
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN101692344B (en) * | 2009-09-15 | 2011-05-25 | 中国科学院上海光学精密机械研究所 | EFM + data decoding method with error detection function for optical disk drive system |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN101692344B (en) * | 2009-09-15 | 2011-05-25 | 中国科学院上海光学精密机械研究所 | EFM + data decoding method with error detection function for optical disk drive system |
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