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| Optical Storage Technical Discussions This Forum is only for experienced users. The postings here might go in depth and be very technical and not understandable for normal users. Please only use this forum for in depth technical stuff. |
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02-02-2006
| #1 (permalink) |
| New on Forum Join Date: Feb 2006
Posts: 4
| Difference between Data Type 2 (packed) and Type 3 (raw) writing? All, I just have a quick question. I'm looking at the MMC4 specs and am trying to differentiate the difference between data type 2 (packed) and type 3 (raw) when writing DAO/96. It appears that type 2 uses interleaved sub-channel data such as: byte 0: P1 Q1 R1 S1 T1 U1 V1 W1 byte 1: P2 Q2 R2 S2 T2 U2 V2 W2 ... byte 95: ... but i'm not sure what the raw form of the subchannel data is or rather what the difference is. Any help is greatly appreciated. Thanks! |
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02-02-2006
| #2 (permalink) |
| Moderator  Join Date: Apr 2001 Location: London, UK
Posts: 520
| Re: Difference between Data Type 2 (packed) and Type 3 (raw) writing? Hi, welcome to the forum. I too had this question in mind a while back, but a member named IpseDixit has enlighten me. Apparently, the packed mode is the CD+G subcode format, i.e. the info used for graphics and text, which can be played on certain CD+G compatible players. Look at this thread: http://club.cdfreaks.com/showthread.php?t=81488 If u scroll down near to the bottom, a very helpful member (not forgetting the others) named taras_g has a code listed there, that does the conversion, i.e. it converts your raw form into the packed form. What it does is that it applies the CD+G delays on them. U can see the CD+G delays are in a table named "offsets". But, I think, this may need attention: only the lower 6 bits of each byte is supposed to be delayed. The upper 2 bits are the normal P & Q bits - same as in raw form. So I think there's supposed to be some sort of skew, between the P & Q with the lower 6 bits. If I have time, I'll try to test out his source code. *Note: naturally, if subcodes RW (lower 6 bits) have no data, i.e. all zeroes, u won't see any difference, I suppose you won't even need to apply the process. It's only a problem if you have CD+G data in those parts. |
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02-02-2006
| #3 (permalink) | |
| New on Forum Join Date: Feb 2006
Posts: 4
| Re: Difference between Data Type 2 (packed) and Type 3 (raw) writing? Quote:
Thanks for the reply and the info. That's exactly what I needed to know. The MMC docs need to be a little more specific in referencing the data format. :-) | |
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04-02-2006
| #4 (permalink) |
| CD Freaks Expert  Join Date: Jan 2004
Posts: 567
| Re: Difference between Data Type 2 (packed) and Type 3 (raw) writing? Not sure if I'm in the right direction here, but think of it this way. If you start with 4 bytes of RAW sub (P-W) and you pack them (R-W), you will have 3 bytes in the end... (you get rid of P and Q and then make 'bytes' out of what bits are left). P1 Q1 R1 S1 T1 U1 V1 W1 byte1 P2 Q2 R2 S2 T2 U2 V2 W2 byte2 P3 Q3 R3 S3 T3 U3 V3 W3 byte3 P4 Q4 R4 S4 T4 U4 V4 W4 byte4 becomes (after stripping the P and Q and packing) R1 S1 T1 U1 V1 W1 R2 S2 byte1 T2 U2 V2 W2 R3 S3 T3 U3 byte2 V3 W3 R4 S4 T4 U4 V4 W4 byte3 sfritzinger, is this what you were asking? Truman, is this what you already tried to say/point to? If so...sorry.  |
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04-02-2006
| #5 (permalink) |
| Moderator Join Date: Apr 2001 Location: London, UK
Posts: 520
| Re: Difference between Data Type 2 (packed) and Type 3 (raw) writing? No need to apologise, RichMan (I think you're more of an expert than me  ). Not quite as above, sorry I wasn't clear. For anyone interested, I hope I can explain...A bit of info ------------- Subcodes R through W are defined specially in CD+G format, which I'm applying here. First, RW are actually used in the usual subcode interleaved state as is: P1 Q1 R1 S1 T1 U1 V1 W1 byte1 P2 Q2 R2 S2 T2 U2 V2 W2 byte2 P3 Q3 R3 S3 T3 U3 V3 W3 byte3 P4 Q4 R4 S4 T4 U4 V4 W4 byte4 It doesn't stop there.. In CD+G, to protect the RW parts, they applied their own Reed-solomon error correction code & also an 8 times interleaving. Note, P & Q subcodes are not affected. Some units they defined in CD+G: RW parts are 6 bits, which they call a symbol (1 RW = 1 symbol) A group of 24 symbols forms 1 pack (24 x symbols = 1 pack) 4 packs forms 1 packet (4 packs = 1 packet). Converting from raw sub to pack sub ----------------------------------- As mentioned above, an 8 times interleaving was added. Note, that this is a second interleaving (causing some confusion), lets call this the CD+G interleaving to distinguish it between the usual subcode interleaving. Fundamentally, you can probably see that the only difference is with this extra CD+G interleaving. Naturally, because we wish to decode, the process is to apply the opposite to CD+G interleaving (i.e. de-interleave) to give u the pack sub. Ok, before we begin, there's one catch, in "8 times" interleaving. It means 8 x 24 symbols = 192 symbols. Basically, on the CD+G, RW subcodes were delayed about 192 symbols. Here's the delay table that delayed each 24 bytes of raw subcode of a sector: Code: //CD+G subcode interleave delays.
unsigned int cdg_interleave_delays[]=
{
192, 258, 317, 383, 292, 242, 342, 367,
200, 225, 250, 275, 300, 325, 350, 375,
208, 233, 217, 283, 308, 333, 358, 267
}; Let's take those raw subcodes of a single sector: Assume it's at sector 10: P00 Q00 R00 S00 T00 U00 V00 W00 byte0 P01 Q01 R01 S01 T02 U01 V01 W01 byte1 P02 Q02 R02 S02 T03 U02 V02 W02 byte2 P03 Q03 R03 S03 T04 U03 V03 W03 byte3 ... P92 Q92 R92 S92 T92 U92 V92 W92 byte92 P93 Q93 R93 S93 T93 U93 V93 W93 byte93 P94 Q94 R94 S94 T94 U94 V94 W94 byte94 P95 Q95 R95 S95 T95 U95 V95 W95 byte95 We apply the cdg_interleave_delays, but we don't delay, instead we wish to do the opposite (un-delaying), so we move bytes forward: Example, For the first one, R01, we move it forward 192 bytes, for S01, we move it forward 258 bytes, and so on. So for the first 24 bytes of raw subs, you should get them spread out into sectors 11 & 12 of the output: Sector 11: ... P192 Q192 R00 S00 T00 U00 V00 W00 byte192 P193 Q193 XXX XXX XXX XXX XXX XXX byte193 P194 Q194 XXX XXX XXX XXX XXX XXX byte194 P195 Q195 XXX XXX XXX XXX XXX XXX byte195 ... P200 Q200 R08 S08 T08 U08 V08 W08 byte200 P201 Q201 XXX XXX XXX XXX XXX XXX byte201 P202 Q202 XXX XXX XXX XXX XXX XXX byte202 P203 Q203 XXX XXX XXX XXX XXX XXX byte203 ... P208 Q208 R16 S16 T16 U16 V16 W16 byte208 P209 Q209 XXX XXX XXX XXX XXX XXX byte209 P210 Q210 XXX XXX XXX XXX XXX XXX byte210 P211 Q211 XXX XXX XXX XXX XXX XXX byte211 ... P216 Q216 XXX XXX XXX XXX XXX XXX byte216 P217 Q217 R18 S18 T18 U18 V18 W18 byte217 P218 Q218 XXX XXX XXX XXX XXX XXX byte218 P219 Q219 XXX XXX XXX XXX XXX XXX byte219 ... P224 Q224 XXX XXX XXX XXX XXX XXX byte224 P225 Q225 R09 S09 T09 U09 V09 W09 byte225 P226 Q226 XXX XXX XXX XXX XXX XXX byte226 P227 Q227 XXX XXX XXX XXX XXX XXX byte227 ... P232 Q232 XXX XXX XXX XXX XXX XXX byte232 P233 Q233 R17 S17 T17 U17 V17 W17 byte233 P234 Q234 XXX XXX XXX XXX XXX XXX byte234 P235 Q235 XXX XXX XXX XXX XXX XXX byte235 ... P240 Q240 XXX XXX XXX XXX XXX XXX byte240 P241 Q241 XXX XXX XXX XXX XXX XXX byte241 P242 Q242 R05 S05 T05 U05 V05 W05 byte242 P243 Q243 XXX XXX XXX XXX XXX XXX byte243 ... P248 Q248 XXX XXX XXX XXX XXX XXX byte248 P249 Q249 XXX XXX XXX XXX XXX XXX byte249 P250 Q250 R10 S10 T10 U10 V10 W10 byte250 P251 Q251 XXX XXX XXX XXX XXX XXX byte251 ... P256 Q256 XXX XXX XXX XXX XXX XXX byte256 P257 Q257 XXX XXX XXX XXX XXX XXX byte257 P258 Q258 R01 S01 T01 U01 V01 W01 byte258 P259 Q259 XXX XXX XXX XXX XXX XXX byte259 ... P264 Q264 XXX XXX XXX XXX XXX XXX byte264 P265 Q265 XXX XXX XXX XXX XXX XXX byte265 P266 Q266 XXX XXX XXX XXX XXX XXX byte266 P267 Q267 R23 S23 T23 U23 V23 W23 byte267 ... P272 Q272 XXX XXX XXX XXX XXX XXX byte272 P273 Q273 XXX XXX XXX XXX XXX XXX byte273 P274 Q274 XXX XXX XXX XXX XXX XXX byte274 P275 Q275 R11 S11 T11 U11 V11 W11 byte275 ... Sector 12 ... P292 Q292 R04 S04 T04 U04 V04 W04 byte292 P293 Q293 XXX XXX XXX XXX XXX XXX byte293 P294 Q294 XXX XXX XXX XXX XXX XXX byte294 P295 Q295 XXX XXX XXX XXX XXX XXX byte295 ... P212 Q212 XXX XXX XXX XXX XXX XXX byte280 P213 Q213 XXX XXX XXX XXX XXX XXX byte281 P214 Q214 XXX XXX XXX XXX XXX XXX byte282 P215 Q215 R19 S19 T19 U19 V19 W19 byte283 ... P300 Q300 R12 S12 T12 U12 V12 W12 byte300 P301 Q301 XXX XXX XXX XXX XXX XXX byte301 P302 Q302 XXX XXX XXX XXX XXX XXX byte302 P303 Q303 XXX XXX XXX XXX XXX XXX byte303 ... P308 Q308 R20 S20 T20 U20 V20 W20 byte308 P309 Q309 XXX XXX XXX XXX XXX XXX byte309 P310 Q310 XXX XXX XXX XXX XXX XXX byte310 P311 Q311 XXX XXX XXX XXX XXX XXX byte311 ... P316 Q316 XXX XXX XXX XXX XXX XXX byte316 P317 Q317 R02 S02 T02 U02 V02 W02 byte317 P318 Q318 XXX XXX XXX XXX XXX XXX byte318 P319 Q319 XXX XXX XXX XXX XXX XXX byte319 ... P324 Q324 XXX XXX XXX XXX XXX XXX byte324 P325 Q325 R13 S13 T13 U13 V13 W13 byte325 P326 Q326 XXX XXX XXX XXX XXX XXX byte326 P327 Q327 XXX XXX XXX XXX XXX XXX byte327 ... P332 Q332 XXX XXX XXX XXX XXX XXX byte332 P333 Q333 R21 S21 T21 U21 V21 W21 byte333 P334 Q334 XXX XXX XXX XXX XXX XXX byte334 P335 Q335 XXX XXX XXX XXX XXX XXX byte335 ... P340 Q340 XXX XXX XXX XXX XXX XXX byte340 P341 Q341 XXX XXX XXX XXX XXX XXX byte341 P342 Q342 R06 S06 T06 U06 V06 W06 byte342 P343 Q343 XXX XXX XXX XXX XXX XXX byte343 ... P348 Q348 XXX XXX XXX XXX XXX XXX byte348 P349 Q349 XXX XXX XXX XXX XXX XXX byte349 P350 Q350 R14 S14 T14 U14 V14 W14 byte350 P351 Q351 XXX XXX XXX XXX XXX XXX byte351 ... P356 Q356 XXX XXX XXX XXX XXX XXX byte356 P357 Q357 XXX XXX XXX XXX XXX XXX byte357 P358 Q358 R22 S22 T22 U22 V22 W22 byte358 P359 Q359 XXX XXX XXX XXX XXX XXX byte359 ... P364 Q364 XXX XXX XXX XXX XXX XXX byte364 P365 Q365 XXX XXX XXX XXX XXX XXX byte365 P366 Q366 XXX XXX XXX XXX XXX XXX byte366 P367 Q367 R07 S07 T07 U07 V07 W07 byte367 ... P372 Q372 XXX XXX XXX XXX XXX XXX byte372 P373 Q373 XXX XXX XXX XXX XXX XXX byte373 P374 Q374 XXX XXX XXX XXX XXX XXX byte374 P375 Q375 R15 S15 T15 U15 V15 W15 byte375 ... P380 Q380 XXX XXX XXX XXX XXX XXX byte380 P381 Q381 XXX XXX XXX XXX XXX XXX byte381 P382 Q382 XXX XXX XXX XXX XXX XXX byte382 P383 Q383 R03 S03 T03 U03 V03 W03 byte383 Notes: The XXX are unknown yet, until we process more raw subs. Have u noticed P & Q stays where they are and don't change. Phew, hope that helps. Now for some coffee... Last edited by Truman; 04-02-2006 at 20:59. |
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04-02-2006
| #6 (permalink) |
| CD Freaks Expert Join Date: Jan 2004
Posts: 567
| Re: Difference between Data Type 2 (packed) and Type 3 (raw) writing? Oops, seems I was thinking packed vs RAW instead of interleaved vs deinterleaved.  I like your delay table. I should have done it that way instead of like this: Code: BOOL RW_Convert::Interleave(unsigned char *In, unsigned char *Out)
{
//this function takes the input pack and interleaves it throughout a total of 8 packs
//the input is a pointer to a buffer that contains 24 bytes
//the output is a pointer to a buffer that is 8*24 bytes
int offset=0;
Out[0] = In[offset++];
Out[(2*24)+18] = In[offset++];
Out[(5*24)+5] = In[offset++];
Out[(7*24)+23] = In[offset++];
Out[(4*24)+4] = In[offset++];
Out[(2*24)+2] = In[offset++];
Out[(6*24)+6] = In[offset++];
Out[(7*24)+7] = In[offset++];
Out[8] = In[offset++];
Out[(1*24)+9] = In[offset++];
Out[(2*24)+10] = In[offset++];
Out[(3*24)+11] = In[offset++];
Out[(4*24)+12] = In[offset++];
Out[(5*24)+13] = In[offset++];
Out[(6*24)+14] = In[offset++];
Out[(7*24)+15] = In[offset++];
Out[16] = In[offset++];
Out[(1*24)+17] = In[offset++];
Out[(1*24)+1] = In[offset++];
Out[(3*24)+19] = In[offset++];
Out[(4*24)+20] = In[offset++];
Out[(5*24)+21] = In[offset++];
Out[(6*24)+22] = In[offset++];
Out[(3*24)+3] = In[offset];
return 1;
} |
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