Date: Fri, 19 Jul 96 02:17:21 +0100 From: Jean-Marc Zucconi <jmz@cabri.obs-besancon.fr> To: joerg_wunsch@uriah.heep.sax.de Cc: freebsd-scsi@freebsd.org Subject: Re: CD driver Message-ID: <9607190117.AA14305@cabri.obs-besancon.fr> In-Reply-To: <199607181903.VAA06840@uriah.heep.sax.de> (message from J Wunsch on Thu, 18 Jul 1996 21:03:45 %2B0200 (MET DST))
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>>>>> J Wunsch writes: > Hi all, > i'm currently playing with some improvements to the (SCSI) CD driver. > I've got the first prototype of multi-track support already running, > and have been playing a little with CD-DA. (Sheesh, i should really > get a soundcard, i guess. :) Oh you will need to fix the sound drivers too :-) I don't know if there is a mainboard/soundcard/driver-version able to play 16bit/44.1KHz sound. I had some success 1 year ago with a pas16, but I am sure you will have problems with -current and a GUS max :-( > Alas, it seems that each vendor picked a different method to allow > digital reading of CD-DA tracks. The SCSI-2 specs made the IMHO big > mistake to forbid reading these data with a regular READ command. > (The drive _must_ return BLANK CHECK / Illegal mode for this track > when attempting to read CD-DA data.) So now, some of the vendors > apparently enable it by using a vendor-specific `density code' in the > MODE SELECT block descriptor (0x82, applicable to at least the Toshiba > 3401 and higher), followed by a regular read. Other drives seem to > use a specific command (0xd8) that is similar to READ(12) but reads > audio data (reported for Plextor, my Toshiba 3401 can also do this, > but, the Toshiba 3501 rejects it). I didn't find anything specific in > the CD-R writer specs for my Plasmon, so i assume it can read them > regularly (perhaps requires a MODE SELECT with a block size of 2352 > before, i have to test this). > The big question now is how to place the hooks in the CD driver that > allow for the various methods, and how to assign/enable the hooks. > They must be applicable to each device separately, since it's > certainly possible that someone has two or more different drives. I > thought of using LKM's for it, but think this will be difficult for > multiple different drives. And it may happen that some drives forbid totally CD-DA. I think you need to select the method according to the drive identification and then to have a manufacturer/model -> method table somewhere. > While we are at it, does anybody know of other methods to enable > CD-DA? I have (had? - I have not tested it for a long time) CD-DA working with my sony drives, using the 0xd9 scsi command. I implemented it with an additional ioctl. > -- > cheers, J"org > joerg_wunsch@uriah.heep.sax.de -- http://www.sax.de/~joerg/ -- NIC: JW11-RIPE > Never trust an operating system you don't have sources for. ;-) Jean-Marc _____________________________________________________________________________ Jean-Marc Zucconi Observatoire de Besancon F 25010 Besancon cedex PGP Key: finger jmz@cabri.obs-besancon.fr =============================================================================
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