Be used for the coding method of the modulation code of high density compact disc
Technical field
The invention belongs to the CD storage technique field, be specifically related to the design of CD modulation code, can in HIGH-DENSITY OPTICAL STORAGE equipment, use.
Technical background
At present, traditional DVD video disc capacity can't satisfy the high power capacity requirement of watching the high sharpness video program, though gone out Blu-ray Disc (its capacity single-surface single-layer can reach 25G) abroad, but its expensive cost can't be promoted it in present market, therefore, a kind of high power capacity video disc based on the ruddiness technology of exploitation is imperative.Meanwhile, the production firm of China DVD disc player is because of the problem of DVD copyright patent, and its existence is subjected to very big threat.In order to break away from expensive patent royalty burden, be badly in need of a kind of new multimedia CD modulation code of design, so that the multimedia disc player production of China has the stronger market competitiveness with own intellecture property.
The CD modulating-coding characteristic of DVD is as follows:
1. coding principle
What DVD adopted is the EFM-Plus modulation code, and run length is RLL (2,10), and code check is 8/16.Work as d=2, during k=10, the max cap. of sign indicating number is 0.5418, so code check can only be about 1/2.
What EFM-Plus adopted is that state relies on the fixed length packets sign indicating number.Rely in the sign indicating number at state, the fixed-length code (FLC) code word that is associated with the information source code word of a regular length is designed to depend on previous coding codeword.The EFM-Plus sign indicating number has 4 states, and each state is divided by the type of the code word that enters, leaves given state.After having stipulated the division condition, can introduce t
I, jLeave state i and the code word number of the j that gets the hang of among the expression 4*4 state-transition matrix T.
From each row of T, find out to have 351 code word outputs at least from each state.Scrambler is corresponding with it 351 output code words that the source code word of input is assigned in each state, and the code word that exceeds is deleted.After setting up corresponding relation, provide source code word and given coder state, then scrambler gives the information of NextState simultaneously with regard to exportable corresponding passage code word.Because input only need be held 256 source code words, so EFM-Plus has 2 coding schedules, one is 256 master meter (see figure 1), and another is 87 an alternative table (see figure 2), preceding 87 source code words just have 2 tables optional when encoding like this, thereby reach the effect that control reduces low-frequency component.
2. decoding principle
Current channel code adds the X of next channel code
3Position and X
15The position can solve the information source code word.
B(t)=H
-1{X(t),X
15(t+1),X
3(t+1)}
3. DC control
The low-frequency component of EFM-Plus suppresses or the method for DC control is the RDS (Running digitalsum) of control code word.88 channel codes that have more are used as source code word 0-87 alternative channel code, and the principle of selecting alternative channel code is the RDS minimum that makes the integral passage sign indicating number.
Simultaneously, the selection of synchronous code also can help to control RDS.EFM-Plus has designed 7 groups of synchronous code (see figure 3)s, and the synchronous code under certain state can be selected in Primary Synchronisation Code and alternative synchronous code, thereby obtains less DSV (Digital Sum Value).
In addition, when 88 to 255 source code word is encoded, if state is 1 or 4, then can select a coding codeword in 1 state or 4 states, satisfy under the prerequisite of run-length restriction, the standard of selection is that DSV is the smaller the better.The main deficiency of this modulation code is:
Capacity is less, RLL parameter d=2 that the modulation code of DVD is got, and the max cap. of sign indicating number is 0.5418, so code check can only be about 1/2, this standard for new generation of high density ruddiness CD single face 15GB is not enough, code efficiency has much room for improvement.
Summary of the invention
The objective of the invention is to design a kind of coding method that is used for the modulation code of high density compact disc, the modulating-coding that is fit to NVD (general optic disc of future generation) channel characteristic, this modulation code has higher code efficiency, so that CD has bigger effective storage capacity, its DC component control ability does not descend too much.
Technical scheme of the present invention is: a kind of coding method that is used for the modulation code of high density compact disc is characterized in that: adopt run length RLL (1,10), code check gets 4/6; In source data, add the DC control bit, improve the ability of control DC component;
The code word that satisfies the d-k requirement in 6 bit word has 21 kinds, select 16 kinds as basic coding code word formation basic coding table, in remaining 5 kinds of code words head and the tail all be 0 code word as connector, substitution table is exactly the combination of basic code word and connector, substitution table length is 56;
Adopt the forward sight coding to solve the cascade collision problem of code word, the source data of 4 bit of forward sight during each the modulation, if being associated with, the code word level after the code word after the current data modulation and the forward sight data-modulated conflicts, then the code words that replace these 2 groups generations to conflict with the code word in the substitution table; Otherwise, then current data is modulated.
The aforesaid coding method that is used for the modulation code of high density compact disc is characterized in that: add a P control bit every 288 bytes in source data, selection DSV less P in modulation back realizes the control to DSV.
The aforesaid coding method that is used for the modulation code of high density compact disc is characterized in that: per 108 bytes of the data after the modulation are added synchronous code, and synchronous code has 2 groups, according to the state adding of current code word.
Ultimate principle of the present invention is:
1. long channel bit length and higher code check
(d=1, between the 11T, wherein T is a channel bit length to the brigade commander that restriction k=10) shows the physical record spot at 2T.In theory (d=1, sign indicating number capacity k=10) is 0.6909, the code fetch rate is 4/6 in the design; In contrast, (d=2, sign indicating number capacity k=10) is 0.5418, and the code check of EFM sign indicating number is 8/17, the code check of EFM+ is 8/16=1/2.Therefore this modulation code has higher efficient, has increased recording capacity.
The RLL modulation code has 2 important performance index: modulation rate and density rate.Modulation rate R=m/n, R are big more to show that the efficient of coding is high more; Density rate DR=R (1+d), what DR represented is the raising ability of modulation system to storage density.Table 4 has compared the Specifeca tion speeification index of RLL (1,10) sign indicating number and current several popular RLL modulation code.
2. in the bit stream of source data, add the DC control bit
Be added in the channel bit code stream differently with DC control bit among EFM and the EFM+, the DC control bit of (1,10) modulation code is to be added in the bit stream of source data.Illustrate as follows:
Consider source data bit stream " P010 0110 ", wherein ' P ' DC control bit (or claiming merge bit) for adding.' if P '=' 1 ', (reference table 3) obtains " 100,010 010010 " after ovennodulation so, is converted to " 000,011 100011 " through a NRZI again, its digital distance of swimming and DSV=+1; If ' P '=' 0 ' obtains " 001,001 010010 " so after ovennodulation, be converted to " 110,001 100011 " through a NRZI again, its digital distance of swimming and DSV=0.By selecting the value of suitable ' P ', just can control the polarity of DSV like this, thus the flip-flop of controlling recording signal and low frequency component.And the expense of adding the DC control bit in source data is also smaller, is about 0.1494%; In contrast, the EFMPlus sign indicating number adds the DC control bit in streams of code words, and expense is about 58%.
3. adopt the forward sight coding
Determine whether should replace with another kind of coding codeword according to coding codeword situation on the horizon to current coding codeword.
The code word that satisfies the d-k requirement in 6 bit word has 21 kinds, with ' 1 ' ending and the conflict that will produce d with ' 1 ' the code word cascade that starts, therefore according to reduce conflict as far as possible but reserve the principle of enough connectors again, select 16 kinds as the basic coding code word.
In the basic coding table, itself all meets the restriction of run length each code word, then will violate the restriction of run length when the part code word in them is carried out cascade, the restriction of then violating d as A and I cascade.Therefore when such code word cascade, just with the replacement of the code word in the substitution table.Substitution table is constituted by basic code word and connector.
And when replacing,, otherwise can produce new conflict if the code word after former code word with 0 beginning, is then replaced also must be with 0 beginning.
4. the design of synchronous code
2 groups of synchronous codes are arranged: " 100000000000 " and " 000000000001 ".
Per 108 bytes of data behind the coding are added synchronous code, then add synchronous code " 000000000001 " if current channel code word state is 0 (i.e. ' 0 ' beginning); If being 1 (i.e. ' 1 ' beginning), current channel code word state then adds synchronous code " 100000000000 ".
Advantage of the present invention and beneficial effect are:
Adopt run length RLL (1,10), long channel bit length and bigger sign indicating number capacity are arranged; Code check gets 4/6, and higher code efficiency is arranged; Adopt forward sight (look-ahead) coding, solve the cascade collision problem of code word; In source data, add the DC control bit, improve the ability of control DC component.The modulation coding method that utilizes the present patent application to propose carries out 4/6 modulation with source data, and code efficiency increases by 1% than EFM-Plus, and by adding the DC control bit, greatly reduces DC component, reduces about 90% when not adding.
Have capacity and the code efficiency higher than DVD, the single-surface double-layer capacity can reach 13G, satisfies the requirement of HD video program.Simultaneously, its DC component within the acceptable range, maximum DSV is 2 times of DVD, code check improves 33.3% than DVD, code efficiency is than the high one percentage point of DVD.
Description of drawings
Fig. 1 is the EFM-Plus coding schedule master meter of table 1 part.
Fig. 2 is the alternative table of EFM-Plus coding schedule of table 2 part.
Fig. 3 is the synchronous code of table 3EFM-Plus.
Fig. 4 is the comparison of table 4RLL modulation system Specifeca tion speeification.
Fig. 5 is RLL (1,10) the modulation basic coding table of table 5 embodiment of the invention.
Fig. 6 is the substitution table of table 6 at the d=1 restriction.
Fig. 7, the multi-medium data modulating-coding process flow diagram 1 of the embodiment of the invention.
Fig. 8, the multi-medium data modulating-coding process flow diagram 2 of the embodiment of the invention.
Fig. 9, the decoding process figure of the embodiment of the invention.
Concrete embodiment
Embodiments of the invention have given statement by Fig. 5 (table 5), Fig. 6 (table 6), Fig. 8 and Fig. 9.Below in conjunction with accompanying drawing (table), be further described.
1. basic coding table design
The basic coding table is seen Fig. 5, and 16 kinds of code words are arranged.Satisfy d=1, the long code word one of the 6bit of k=10 has 21 kinds, selects 16 kinds as the basic coding code word.
At first according to basic coding table coding, there is not when conflict when current code word with the coding codeword cascade after the forward sight code word is modulated, then adopt the coding codeword in the basic coding table.
In general, the method for DC control allows enter code word as much as possible that 2 kinds of optional code words are arranged after ovennodulation exactly, and the polarity difference of " 1 " in these 2 code words.Because it is to add the DC control bit in source code that the design considers the DC control method that adopts, be that the polarity of 1 source code code word corresponding codes code word " 1 " is opposite so will make Hamming distance in the source code during design code table.For example, the polarity of " 0000 " corresponding codes code word " 1 " is odd number, and then the polarity of " 0001 ", " 0010 ", " 0100 " and " 1000 " corresponding codes code word " 1 " is even number just.
2. replace the code table design
Current 4 bit word are called P, next 4 bit word are called S.Substitution table at the d=1 restriction is seen Fig. 6.
16 kinds of code words in the basic coding table, the restriction that the code word that wherein has can not be violated d with any other coding codeword cascade, as 000010, such a code word is just as " connector ".
When the code word in the basic coding table produces the cascade conflict, just add that with a basic code word connector replaces original afoul 2 basic code words, solves the conflict of cascade.As: during 0000 and 1000 cascades, the code word of looking into basic coding table (see figure 5) obtains 100001.100000, has produced the conflict of d, therefore looks into the substitution table (see figure 6), and obtain replacing code word: 000001.001010 replaces former basic code word, the conflict that has solved d.
Because the code word with " 1 " ending in the basic coding table has 7, the code word that starts with " 1 " has 8, therefore have 56 kinds of cascade conflicts, so substitution table length is 56 (see figure 6)s.
3. synchronous code design
2 groups of synchronous codes: 000000000001 and 100000000000.
Current state is 0 (code word of synchronous code back is the first to be ' 0 '), selects synchronous code 000000000001; Current state is 1 (code word of synchronous code back is the first to be ' 1 '), selects synchronous code 100000000000.Can guarantee like this synchronous code and being connected of code word data not to violate the regulation of d.Because k=10, so when the signal that detects above 11T, can judge synchronous code to have occurred.
4. coding flow process
The coding flow process as shown in Figure 7 and Figure 8.Wherein, the process of encode () is as follows:
1) input 4 bit word and next 4 bit word in scrambler;
2) the basic coding table according to RLL (1,10) modulation carries out code conversion to current 4 enter code words and next 4 bit word, obtains 26 code word P and S;
3) judge whether code word P and S violate the restriction of d=1, if, then according to P and S being replaced, obtain legal new P and new S at the substitution table of d=1 restriction, enter step 4) then; If not, directly enter step 5);
4) at present clock output code word P, wait for that at next clock output code word S, get back to step 1) then, the circulation above-mentioned steps finishes up to coding;
5) at present clock output code word P, S is composed to P as new current code word; Read in next 4 bit word, and according to the basic coding table of RLL (1,10) modulation 4 new bit word are carried out code conversion and obtain new S, get back to step 3) then; If do not have code word to read in to the end of file, then directly at next clock output code word P; The circulation above-mentioned steps finishes up to coding.
5. decoding process
The coding flow process as shown in Figure 9.Wherein, the process of decode () is as follows:
1) input 6 bit word P and 6 S of next code word in demoder;
2) judge that whether P and Q are the special code words of to violate the d=1 restriction and being used for replacing in order to eliminate, if the substitution table at the d=1 restriction that adopts during then according to coding carries out conversion to code word P and S, enter step 3) then; If not, then directly enter step 4);
3) in the conversion of present clock output code word P,, get back to step 1) then, finish up to decoding in the conversion of next clock output code word S;
RLL (1,10) the modulation basic coding table that adopts during 4) according to coding carries out conversion to P, and in the conversion that present clock is exported code word P, S is composed to P, and read in 6 new bit word S, gets back to step 2 then, finishes up to decoding.
In the embodiment of the present invention, the assessment of modulating-coding is as follows:
According to the characteristics of high density compact disc multimedia application, source data has been carried out RLL (1,10; 4,6) modulating-coding.
The modulation code of its volume ratio DVD has increased by 33.3%, and code efficiency has improved one percentage point.
Maximum DSV has reduced 1 to 2 order of magnitude when not adding the DC control bit, but maximal value is about 2 times of DVD.
Therefore, this modulation code has the feasibility that is applied to high density compact disc raising CD effective storage capacity.