Digital Audio on SCSI Bus

CD-ROM Drives that Support Audio over SCSI
CD-DA SCSI Commands
Software that Supports CD-DA Transfers


CD-ROM Drives that Support Audio over SCSI

Brad Parker says:
   Turns out that very few SCSI CD-ROMs have the capability to run the digital audio through the SCSI connection. Looks like the Toshiba's (and their IBM siblings) are in! Amazing.

From the alt.cdrom.faq
Enhanced Int CDROM II Drive 32G2958 Toshiba TXM-3401-based
Enhanced Ext CDROM II Drive 3510005 Toshiba TXM-3401-based
IBM PS/2 CDROM II Drive - Toshiba TXM-3301-based

37. How do I read an audio cd track as digital data?

Most CD-ROM drives cannot decode audio information. There are firmware and data path reasons why it doesn't work.

The following drives can do digital audio extraction over the SCSI bus:
Apple 300, 300i (Sony CDU-8003, CDU-8003A)
Apple's "New" CD (Matsushita CR-8004)
Chinon CDS-535 (note: needs v2.0 firmware "Q20" or "R20")
NEC CDR 500, CDR 510, CDR 600 (MultiSpin 3x series)
NEC CDR 400 (MultiSpin 3xp portable)
NEC CDR 900 (MultiSpin 4x Pro quadruple speed)
NEC CDR 84-1 (74-1) needs special new firmware upgrade from NEC
Sony CDU-561
Toshiba XM 3301TE (Silicon Graphics version)
Toshiba XM 3401TA, XM 3401B
Toshiba XM 3401TE (Silicon Graphics, and Sun versions)
Toshiba XM 4101TA Toshiba XM 5301TA (Thanks to Al Brandt)

The Hitachi 6750S might, if the rumors prove true.

Looking at the specs for the XM 4101B (dead), it says "This drive supports CD-DA transfer over SCSI function that the host system can read CD audio data". (also says that it can be used as an independent CD audio player separate from the system).

I think there are more drives that support CD-DA from Toshiba.


CD-DA SCSI Commands (Toshiba and maybe other mfgs)

From alt.cdrom.faq
   For the Toshiba drives, you issue a MODE SELECT command with density code 0x82 and then all reads with an LBA inside a digital audio track will return 2352 bytes audio samples / block.
   There are several ways to read digital audio from Sony CDU 561 and Sony CDU 8003 mechanisms. Note that the technique of merely setting the density (0x82) using MODE SELECT SCSI command as on Toshiba TXM-3401s will not work.
   Here are three ways to read digital audio Red Book standard audio track data across the SCSI bus into your computer complete with all sound processing already performed (For example the
   CIRC routine already run and the output is LRLRLR pairs of 16 bit digital audio samples 2352 bytes per CD-ROM block.

Method 1 : READ CD-DA SCSI command 0xD8

Byte 0: D8
1: <LUN stuff> 0
2: <4th most significant byte of logical block address>
3: <3rd byte>
4: <2nd>
5: <1st, lowest of the address>
6: <4th most significant byte of transfer length
7: <3rd byte>
8: <2nd>
9: <1st, lowest of the number of contiguous blocks to transfer>
10: <special subcode selector> (0 = normal 2352, other values 01,02,03)
11: <control>

Method 2 : READ CD-DA MSF SCSI command 0xD9

Byte 0: D9
1: <LUN stuff> 0
2: 0
3: <starting minute in binary not BCD>
4: <starting second in binary not BCD>
5: <starting frame (75th of a second) in binary not BCD>
6: 0
7: <ending minute in binary not BCD>
8: <ending second in binary not BCD>
9: <ending frame (75th of a second) in binary not BCD>
10: <special subcode selector> (0 = normal 2352, other values 01,02,03)
11: <control>

For this one you will want 2352, but I have not tried this technique and Sony recommends the special streaming commands.

Warning: For high quality use large transfers but QUICKLY reissue another command as soon as a command is completed. The head must never ment is entitled "Toshiba CD-ROM, SCSI-2 Interface Specifications, Ver. 6.0, Issued Jul., 1992". The cost is $7.64 + $4 shipping. Note that this is extremely technical material, and won't be useful to the average user.


Software that Supports CD-DA Transfers

From Al Brandt:
   I use that software that came with my Rio Player. Works fine with an Adaptec card and the Smart and Friendly. My Toshiba (don't know the model #) seemed to work fine as well.

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