MMC4 SET CD SPEED change to SET SPEED

keiji_katata at post.pioneer.co.jp keiji_katata at post.pioneer.co.jp
Fri Aug 29 04:42:15 PDT 2003


* From the T10 Reflector (t10 at t10.org), posted by:
* keiji_katata at post.pioneer.co.jp
*

Hello Bill (and David), I do not agree this change done in "T10/02-187.r0".

Because;

1. MMC4 becomes incompatible with MMC3.

MMC3 "4.2.4 High Speed CD-RW media recording" and "6.4.3.34 Real Time
Streaming Feature (0107h)" says SET CD SPEED command is option for CD. Also
MMC4 says SET CD SPEED command is option in Real Time Streaming Feature
(0107h). If some media type wants it mandatory, please specify in the media
specification.

2. SET CD SPEED command has too much trouble to expand for future.

Each CD drive models have different implementation of the parameter e.g.
2353 bytes/scoter v.s. 2048 bytes/scoter, 1024 bytes/1K bytes v.s. 1000
bytes/1K bytes. Software and PC manufacture have different implementation
requirement to the drive manufacture, so a drive manufacture has different
combination and can not change the specific implementation for the specific
customer. Software venders need to have Inquiry database to use selectable
Write Speed of the specific CD drive. So In MMC3, Get Performance command
and Set Streaming command were created.

3. No command provides possible Speed parameter list that host can use in
SET CD SPEED command.

Because Mode Page 2Ah is obsoleted and useless other than CD. And SET CD
SPEED command is not allowed to report any error (drive shall select some
near Writing Speed for any request), so host can not detect what Write
Speed is selected by device. So host can not user SET CD SPEED command
without drive Inquiry database.

4. SET CD SPEED command can not cover Zone rotation control media.

SET CD SPEED command can not cover DVD-RAM, +RW from the beginning. So Rob
Sims of HP proposed to create Get Performance command and Set Streaming
command. And DVD Forum group accepted the HP's proposal.

5. T10/02-187.r0 shows that the discussion was technically wrong.

"In Discussion, Set CD Speed:" of section 7.2.3 said "Set Streaming is
described as being associated with the READ (12) with the streaming bit set
to 1." This is technically wrong. Get Performance command has the
capability to show Streaming (data transfer rate) profile of Zone'ed media
e.g. DVD-RAM 2,7G, +RW 3G and Sparing Speed drop of Hardware Defect
Management device. Streaming bit setting of Read12 command, Write12 command
have no relationship with the Get Performance command capability. Of cause,
Streaming bit setting never affect Set Streaming command.

6. An ATAPI tape device uses SET CD SPEED command.

MMC does not cover tape device. I checked T10 document and Minutes from
document.97 to document.03. There is not discussion and specification,
proposal of SET CD SPEED command for tape device. This means SET CD SPEED
command is vender specific definition for "SCSI Stream Commands - 2"
device. If tape device wants to use SET SPEED command, it shall be
described in SPC or SSC, not in MMC.


Bill, No.1 reason makes me much trouble. Some Logo Licence program and
Customer Test program are based on MMC3 document. So if MMC4 has
incompatible description with MMC3, Market and Customers of MMC drives are
confused too much. Pioneer can not accept this unreasonable crash.


Best regards,

Keiji Katata
PIONEER CORP.



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