Lead-in, TOC & multisession

superg · 2022-03-26 17:54:13

superg
Moderator
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Registered: 2019-05-25
Posts: 1,221

I want to share my findings about general layout of a multisession disc.
Apparently what I see here contradicts with common redump knowledge so this might be important.

In particular, my findings show that each session has it's own TOC in lead-in which lists track entries only for that session.
I will demonstrate that on http://redump.org/disc/75764/

The disc has the following TOC:

TOC:
  session 1
    track 01 { audio, LBA:      0 ..  22641, length:  22642, MSF: 00:02:00-05:03:66 }
    track 02 { audio, LBA:  22642 ..  62829, length:  40188, MSF: 05:03:67-13:59:54 }
    track 03 { audio, LBA:  62830 ..  85925, length:  23096, MSF: 13:59:55-19:07:50 }
    track 04 { audio, LBA:  85926 .. 108706, length:  22781, MSF: 19:07:51-24:11:31 }
    track 05 { audio, LBA: 108707 .. 127440, length:  18734, MSF: 24:11:32-28:21:15 }
    track 06 { audio, LBA: 127441 .. 149520, length:  22080, MSF: 28:21:16-33:15:45 }
    track 07 { audio, LBA: 149521 .. 185511, length:  35991, MSF: 33:15:46-41:15:36 }
    track 08 { audio, LBA: 185512 .. 198852, length:  13341, MSF: 41:15:37-44:13:27 }
    track 09 { audio, LBA: 198853 .. 208969, length:  10117, MSF: 44:13:28-46:28:19 }
    track 10 { audio, LBA: 208970 .. 219014, length:  10045, MSF: 46:28:20-48:42:14 }
  session 2
    track 11 {  data, LBA: 230415 .. 262720, length:  32306, MSF: 51:14:15-58:24:70 }

I extracted both session lead-ins using negative PLEXTOR readings and here are the snippets of both sessions decoded subchannel Q to illustrate.

session 1:

[LBA:   -235] control: 0000, ADR: 1, tno: 00, P/I: 08, MSF: 99:58:65, zero: 00, A/P MSF: 41:15:37, crc: DCEE (+)
[LBA:   -234] control: 0000, ADR: 1, tno: 00, P/I: 08, MSF: 99:58:66, zero: 00, A/P MSF: 41:15:37, crc: 0E00 (+)
[LBA:   -233] control: 0000, ADR: 1, tno: 00, P/I: 08, MSF: 99:58:67, zero: 00, A/P MSF: 41:15:37, crc: 5FAA (+)
[LBA:   -232] control: 0000, ADR: 5, 00 C0 00 00 00 00 95 00 00, crc: 17A5 (+)
[LBA:   -231] control: 0000, ADR: 5, 00 C0 00 00 00 00 95 00 00, crc: 17A5 (+)
[LBA:   -230] control: 0000, ADR: 5, 00 C0 00 00 00 00 95 00 00, crc: 17A5 (+)
[LBA:   -229] control: 0000, ADR: 1, tno: 00, P/I: 09, MSF: 99:58:71, zero: 00, A/P MSF: 44:13:28, crc: DB86 (+)
[LBA:   -228] control: 0000, ADR: 1, tno: 00, P/I: 09, MSF: 99:58:72, zero: 00, A/P MSF: 44:13:28, crc: 0968 (+)
[LBA:   -227] control: 0000, ADR: 1, tno: 00, P/I: 09, MSF: 99:58:73, zero: 00, A/P MSF: 44:13:28, crc: 58C2 (+)
[LBA:   -226] control: 0000, ADR: 5, 00 B0 51 12 15 02 58 24 71, crc: 7EDC (+)
[LBA:   -225] control: 0000, ADR: 5, 00 B0 51 12 15 02 58 24 71, crc: 7EDC (+)
[LBA:   -224] control: 0000, ADR: 5, 00 B0 51 12 15 02 58 24 71, crc: 7EDC (+)
[LBA:   -223] control: 0000, ADR: 1, tno: 00, P/I: 10, MSF: 99:59:02, zero: 00, A/P MSF: 46:28:20, crc: 9562 (+)
[LBA:   -222] control: 0000, ADR: 1, tno: 00, P/I: 10, MSF: 99:59:03, zero: 00, A/P MSF: 46:28:20, crc: C4C8 (+)
[LBA:   -221] control: 0000, ADR: 1, tno: 00, P/I: 10, MSF: 99:59:04, zero: 00, A/P MSF: 46:28:20, crc: 10AF (+)
[LBA:   -220] control: 0000, ADR: 5, 00 C0 00 00 00 00 95 00 00, crc: 17A5 (+)
[LBA:   -219] control: 0000, ADR: 5, 00 C0 00 00 00 00 95 00 00, crc: 17A5 (+)
[LBA:   -218] control: 0000, ADR: 5, 00 C0 00 00 00 00 95 00 00, crc: 17A5 (+)
[LBA:   -217] control: 0000, ADR: 1, tno: 00, P/I: A0, MSF: 99:59:08, zero: 00, A/P MSF: 01:00:00, crc: 76AC (+)
[LBA:   -216] control: 0000, ADR: 1, tno: 00, P/I: A0, MSF: 99:59:09, zero: 00, A/P MSF: 01:00:00, crc: 2706 (+)
[LBA:   -215] control: 0000, ADR: 1, tno: 00, P/I: A0, MSF: 99:59:10, zero: 00, A/P MSF: 01:00:00, crc: 01AA (+)
[LBA:   -214] control: 0000, ADR: 5, 00 B0 51 12 15 02 58 24 71, crc: 7EDC (+)
[LBA:   -213] control: 0000, ADR: 5, 00 B0 51 12 15 02 58 24 71, crc: 7EDC (+)
[LBA:   -212] control: 0000, ADR: 5, 00 B0 51 12 15 02 58 24 71, crc: 7EDC (+)
[LBA:   -211] control: 0000, ADR: 1, tno: 00, P/I: A1, MSF: 99:59:14, zero: 00, A/P MSF: 10:00:00, crc: 8710 (+)
[LBA:   -210] control: 0000, ADR: 1, tno: 00, P/I: A1, MSF: 99:59:15, zero: 00, A/P MSF: 10:00:00, crc: D6BA (+)
[LBA:   -209] control: 0000, ADR: 1, tno: 00, P/I: A1, MSF: 99:59:16, zero: 00, A/P MSF: 10:00:00, crc: 0454 (+)
[LBA:   -208] control: 0000, ADR: 5, 00 C0 00 00 00 00 95 00 00, crc: 17A5 (+)
[LBA:   -207] control: 0000, ADR: 5, 00 C0 00 00 00 00 95 00 00, crc: 17A5 (+)
[LBA:   -206] control: 0000, ADR: 5, 00 C0 00 00 00 00 95 00 00, crc: 17A5 (+)
[LBA:   -205] control: 0000, ADR: 1, tno: 00, P/I: A2, MSF: 99:59:20, zero: 00, A/P MSF: 48:42:15, crc: 4F83 (+)
[LBA:   -204] control: 0000, ADR: 1, tno: 00, P/I: A2, MSF: 99:59:21, zero: 00, A/P MSF: 48:42:15, crc: 1E29 (+)
[LBA:   -203] control: 0000, ADR: 1, tno: 00, P/I: A2, MSF: 99:59:22, zero: 00, A/P MSF: 48:42:15, crc: CCC7 (+)
[LBA:   -202] control: 0000, ADR: 5, 00 B0 51 12 15 02 58 24 71, crc: 7EDC (+)
[LBA:   -201] control: 0000, ADR: 5, 00 B0 51 12 15 02 58 24 71, crc: 7EDC (+)
[LBA:   -200] control: 0000, ADR: 5, 00 B0 51 12 15 02 58 24 71, crc: 7EDC (+)
[LBA:   -199] control: 0000, ADR: 1, tno: 00, P/I: 01, MSF: 99:59:26, zero: 00, A/P MSF: 00:02:00, crc: 02FB (+)
[LBA:   -198] control: 0000, ADR: 1, tno: 00, P/I: 01, MSF: 99:59:27, zero: 00, A/P MSF: 00:02:00, crc: 5351 (+)
[LBA:   -197] control: 0000, ADR: 1, tno: 00, P/I: 01, MSF: 99:59:28, zero: 00, A/P MSF: 00:02:00, crc: AA34 (+)
[LBA:   -196] control: 0000, ADR: 5, 00 C0 00 00 00 00 95 00 00, crc: 17A5 (+)
[LBA:   -195] control: 0000, ADR: 5, 00 C0 00 00 00 00 95 00 00, crc: 17A5 (+)
[LBA:   -194] control: 0000, ADR: 5, 00 C0 00 00 00 00 95 00 00, crc: 17A5 (+)
[LBA:   -193] control: 0000, ADR: 1, tno: 00, P/I: 02, MSF: 99:59:32, zero: 00, A/P MSF: 05:03:67, crc: AB7A (+)
[LBA:   -192] control: 0000, ADR: 1, tno: 00, P/I: 02, MSF: 99:59:33, zero: 00, A/P MSF: 05:03:67, crc: FAD0 (+)
[LBA:   -191] control: 0000, ADR: 1, tno: 00, P/I: 02, MSF: 99:59:34, zero: 00, A/P MSF: 05:03:67, crc: 2EB7 (+)
[LBA:   -190] control: 0000, ADR: 5, 00 B0 51 12 15 02 58 24 71, crc: 7EDC (+)
[LBA:   -189] control: 0000, ADR: 5, 00 B0 51 12 15 02 58 24 71, crc: 7EDC (+)
[LBA:   -188] control: 0000, ADR: 5, 00 B0 51 12 15 02 58 24 71, crc: 7EDC (+)
[LBA:   -187] control: 0000, ADR: 1, tno: 00, P/I: 03, MSF: 99:59:38, zero: 00, A/P MSF: 13:59:55, crc: 707D (+)
[LBA:   -186] control: 0000, ADR: 1, tno: 00, P/I: 03, MSF: 99:59:39, zero: 00, A/P MSF: 13:59:55, crc: 21D7 (+)
[LBA:   -185] control: 0000, ADR: 1, tno: 00, P/I: 03, MSF: 99:59:40, zero: 00, A/P MSF: 13:59:55, crc: DB62 (+)
[LBA:   -184] control: 0000, ADR: 5, 00 C0 00 00 00 00 95 00 00, crc: 17A5 (+)
[LBA:   -183] control: 0000, ADR: 5, 00 C0 00 00 00 00 95 00 00, crc: 17A5 (+)
[LBA:   -182] control: 0000, ADR: 5, 00 C0 00 00 00 00 95 00 00, crc: 17A5 (+)
[LBA:   -181] control: 0000, ADR: 1, tno: 00, P/I: 04, MSF: 99:59:44, zero: 00, A/P MSF: 19:07:51, crc: 3086 (+)
[LBA:   -180] control: 0000, ADR: 1, tno: 00, P/I: 04, MSF: 99:59:45, zero: 00, A/P MSF: 19:07:51, crc: 612C (+)
[LBA:   -179] control: 0000, ADR: 1, tno: 00, P/I: 04, MSF: 99:59:46, zero: 00, A/P MSF: 19:07:51, crc: B3C2 (+)
[LBA:   -178] control: 0000, ADR: 5, 00 B0 51 12 15 02 58 24 71, crc: 7EDC (+)
[LBA:   -177] control: 0000, ADR: 5, 00 B0 51 12 15 02 58 24 71, crc: 7EDC (+)
[LBA:   -176] control: 0000, ADR: 5, 00 B0 51 12 15 02 58 24 71, crc: 7EDC (+)
[LBA:   -175] control: 0000, ADR: 1, tno: 00, P/I: 05, MSF: 99:59:50, zero: 00, A/P MSF: 24:11:32, crc: 5B3E (+)
[LBA:   -174] control: 0000, ADR: 1, tno: 00, P/I: 05, MSF: 99:59:51, zero: 00, A/P MSF: 24:11:32, crc: 0A94 (+)
[LBA:   -173] control: 0000, ADR: 1, tno: 00, P/I: 05, MSF: 99:59:52, zero: 00, A/P MSF: 24:11:32, crc: D87A (+)
[LBA:   -172] control: 0000, ADR: 5, 00 C0 00 00 00 00 95 00 00, crc: 17A5 (+)
[LBA:   -171] control: 0000, ADR: 5, 00 C0 00 00 00 00 95 00 00, crc: 17A5 (+)
[LBA:   -170] control: 0000, ADR: 5, 00 C0 00 00 00 00 95 00 00, crc: 17A5 (+)
[LBA:   -169] control: 0000, ADR: 1, tno: 00, P/I: 06, MSF: 99:59:56, zero: 00, A/P MSF: 28:21:16, crc: B92F (+)
[LBA:   -168] control: 0000, ADR: 1, tno: 00, P/I: 06, MSF: 99:59:57, zero: 00, A/P MSF: 28:21:16, crc: E885 (+)
[LBA:   -167] control: 0000, ADR: 1, tno: 00, P/I: 06, MSF: 99:59:58, zero: 00, A/P MSF: 28:21:16, crc: 11E0 (+)
[LBA:   -166] control: 0000, ADR: 5, 00 B0 51 12 15 02 58 24 71, crc: 7EDC (+)
[LBA:   -165] control: 0000, ADR: 5, 00 B0 51 12 15 02 58 24 71, crc: 7EDC (+)
[LBA:   -164] control: 0000, ADR: 5, 00 B0 51 12 15 02 58 24 71, crc: 7EDC (+)
[LBA:   -163] control: 0000, ADR: 1, tno: 00, P/I: 07, MSF: 99:59:62, zero: 00, A/P MSF: 33:15:46, crc: B4CD (+)
[LBA:   -162] control: 0000, ADR: 1, tno: 00, P/I: 07, MSF: 99:59:63, zero: 00, A/P MSF: 33:15:46, crc: E567 (+)
[LBA:   -161] control: 0000, ADR: 1, tno: 00, P/I: 07, MSF: 99:59:64, zero: 00, A/P MSF: 33:15:46, crc: 3100 (+)
[LBA:   -160] control: 0000, ADR: 5, 00 C0 00 00 00 00 95 00 00, crc: 17A5 (+)
[LBA:   -159] control: 0000, ADR: 5, 00 C0 00 00 00 00 95 00 00, crc: 17A5 (+)
[LBA:   -158] control: 0000, ADR: 5, 00 C0 00 00 00 00 95 00 00, crc: 17A5 (+)
[LBA:   -157] control: 0000, ADR: 1, tno: 00, P/I: 08, MSF: 99:59:68, zero: 00, A/P MSF: 41:15:37, crc: 068A (+)
[LBA:   -156] control: 0000, ADR: 1, tno: 00, P/I: 08, MSF: 99:59:69, zero: 00, A/P MSF: 41:15:37, crc: 5720 (+)
[LBA:   -155] control: 0000, ADR: 1, tno: 00, P/I: 08, MSF: 99:59:70, zero: 00, A/P MSF: 41:15:37, crc: 718C (+)
[LBA:   -154] control: 0000, ADR: 5, 00 B0 51 12 15 02 58 24 71, crc: 7EDC (+)
[LBA:   -153] control: 0000, ADR: 5, 00 B0 51 12 15 02 58 24 71, crc: 7EDC (+)
[LBA:   -152] control: 0000, ADR: 5, 00 B0 51 12 15 02 58 24 71, crc: 7EDC (+)
[LBA:   -151] control: 0000, ADR: 1, tno: 00, P/I: 09, MSF: 99:59:74, zero: 00, A/P MSF: 44:13:28, crc: 2CE0 (+)
[LBA:   -150] control: 0000, ADR: 1, tno: 01, P/I: 00, MSF: 00:01:74, zero: 00, A/P MSF: 00:00:00, crc: B9AA (+)

session 2:

[LBA: 230242] control: 0100, ADR: 1, tno: 00, P/I: 11, MSF: 51:11:67, zero: 00, A/P MSF: 51:14:15, crc: C00F (+)
[LBA: 230243] control: 0100, ADR: 1, tno: 00, P/I: 11, MSF: 51:11:68, zero: 00, A/P MSF: 51:14:15, crc: 396A (+)
[LBA: 230244] control: 0100, ADR: 1, tno: 00, P/I: 11, MSF: 51:11:69, zero: 00, A/P MSF: 51:14:15, crc: 68C0 (+)
[LBA: 230245] control: 0100, ADR: 1, tno: 00, P/I: A0, MSF: 51:11:70, zero: 00, A/P MSF: 11:20:00, crc: A806 (+)
[LBA: 230246] control: 0100, ADR: 1, tno: 00, P/I: A0, MSF: 51:11:71, zero: 00, A/P MSF: 11:20:00, crc: F9AC (+)
[LBA: 230247] control: 0100, ADR: 1, tno: 00, P/I: A0, MSF: 51:11:72, zero: 00, A/P MSF: 11:20:00, crc: 2B42 (+)
[LBA: 230248] control: 0100, ADR: 1, tno: 00, P/I: A1, MSF: 51:11:73, zero: 00, A/P MSF: 11:00:00, crc: 4FA9 (+)
[LBA: 230249] control: 0100, ADR: 1, tno: 00, P/I: A1, MSF: 51:11:74, zero: 00, A/P MSF: 11:00:00, crc: 9BCE (+)
[LBA: 230250] control: 0100, ADR: 1, tno: 00, P/I: A1, MSF: 51:12:00, zero: 00, A/P MSF: 11:00:00, crc: FB94 (+)
[LBA: 230251] control: 0100, ADR: 1, tno: 00, P/I: A2, MSF: 51:12:01, zero: 00, A/P MSF: 58:24:71, crc: 77D1 (+)
[LBA: 230252] control: 0100, ADR: 1, tno: 00, P/I: A2, MSF: 51:12:02, zero: 00, A/P MSF: 58:24:71, crc: A53F (+)
[LBA: 230253] control: 0100, ADR: 1, tno: 00, P/I: A2, MSF: 51:12:03, zero: 00, A/P MSF: 58:24:71, crc: F495 (+)
[LBA: 230254] control: 0100, ADR: 1, tno: 00, P/I: 11, MSF: 51:12:04, zero: 00, A/P MSF: 51:14:15, crc: 2E36 (+)
[LBA: 230255] control: 0100, ADR: 1, tno: 00, P/I: 11, MSF: 51:12:05, zero: 00, A/P MSF: 51:14:15, crc: 7F9C (+)
[LBA: 230256] control: 0100, ADR: 1, tno: 00, P/I: 11, MSF: 51:12:06, zero: 00, A/P MSF: 51:14:15, crc: AD72 (+)
[LBA: 230257] control: 0100, ADR: 1, tno: 00, P/I: A0, MSF: 51:12:07, zero: 00, A/P MSF: 11:20:00, crc: 1AB2 (+)
[LBA: 230258] control: 0100, ADR: 1, tno: 00, P/I: A0, MSF: 51:12:08, zero: 00, A/P MSF: 11:20:00, crc: E3D7 (+)
[LBA: 230259] control: 0100, ADR: 1, tno: 00, P/I: A0, MSF: 51:12:09, zero: 00, A/P MSF: 11:20:00, crc: B27D (+)
[LBA: 230260] control: 0100, ADR: 1, tno: 00, P/I: A1, MSF: 51:12:10, zero: 00, A/P MSF: 11:00:00, crc: A190 (+)
[LBA: 230261] control: 0100, ADR: 1, tno: 00, P/I: A1, MSF: 51:12:11, zero: 00, A/P MSF: 11:00:00, crc: F03A (+)
[LBA: 230262] control: 0100, ADR: 1, tno: 00, P/I: A1, MSF: 51:12:12, zero: 00, A/P MSF: 11:00:00, crc: 22D4 (+)
[LBA: 230263] control: 0100, ADR: 1, tno: 00, P/I: A2, MSF: 51:12:13, zero: 00, A/P MSF: 58:24:71, crc: AE91 (+)
[LBA: 230264] control: 0100, ADR: 1, tno: 00, P/I: A2, MSF: 51:12:14, zero: 00, A/P MSF: 58:24:71, crc: 7AF6 (+)
[LBA: 230265] control: 0100, ADR: 1, tno: 11, P/I: 00, MSF: 00:01:74, zero: 00, A/P MSF: 51:12:15, crc: 26C5 (+)

As you can see, session 1 lead-in lists only tracks 1-10 and session 2 lead-in lists only track 11.
(TOC entries in lead-in are usually cyclically repeated in a pack of 3)

I see this on all other pressed multisession discs I own (up to 10) and to me it makes total sense as this looks like compatibility thing for earlier players which don't support multisession and session 2 tracks (usually data) are totally "invisible" there.
When you request disc TOC on a multisession supported drive, it gets both sessions TOC and merges it.

Another directly related side effect is that drives often have problems with reading multisession CD-TEXT (CD-TEXT data is stored in TOC R-W subchannels). I have one such disc with CD-TEXT defined in both sessions and earlier PLEXTOR drives (PX-W5224TA) are able to get only CD-TEXT stored in the first session while later DVD PLEXTOR drives have no problem extracting both session data.

Whole disc decoded subchannel Q for the reference:
https://www.dropbox.com/s/h5cubuo6m95wo … q.zip?dl=0

scsi_wuzzy · 2022-04-12 14:54:08

scsi_wuzzy
Dumper
Offline

Registered: 2015-02-24
Posts: 101

It would be nice if we could ultimately end up with CD images like the ones Near described. Near's article about the CD format hypothesizes about a CD format that just stores all the lead-in sectors (including subchannels) so that we could have a single file raw image format that embedded the TOC the same way the real disc does. Such an image format would handle multisession discs easily.

Of course, it'd be really nice if we could hack some model of drive to just give us the CIRC data (or some other low level data from every sector) directly. I guess it would be akin to the Greaseweazle and similar hardware for dumping raw flux from floppy disks.

superg · 2022-04-12 15:13:09

superg
Moderator
Offline

Registered: 2019-05-25
Posts: 1,221

scsi_wuzzy wrote:

It would be nice if we could ultimately end up with CD images like the ones Near described. Near's article about the CD format hypothesizes about a CD format that just stores all the lead-in sectors (including subchannels) so that we could have a single file raw image format that embedded the TOC the same way the real disc does. Such an image format would handle multisession discs easily.

I already have something very close to that but it's not redump scope really. You can't get all the lead-in sectors because of the mechanical limitations of the drive (how close laser head assembly can get to the center of the disc). Plextor allows us to start reading from some place in the TOC and that is good enough given that TOC is repeating itself.
Custom drive firmware would be an ambitious project for sure but that's very complex task.

Lead-in, TOC & multisession

Posts: 3

1 Topic by superg 2022-03-26 17:54:13

2 Reply by scsi_wuzzy 2022-04-12 14:54:08

3 Reply by superg 2022-04-12 15:13:09

Posts: 3