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rocky
2004-07-29 05:32:11 +00:00
parent dc3073165c
commit ae7b480384
1 changed files with 45 additions and 28 deletions
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doc/libcdio.texi
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@@ -46,7 +46,7 @@ development.''
@titlepage
@title GNU libcdio library
@subtitle $Id: libcdio.texi,v 1.24 2004/07/28 22:02:55 rocky Exp $
@subtitle $Id: libcdio.texi,v 1.25 2004/07/29 05:32:11 rocky Exp $
@author Rocky Bernstein et al.
@page
@@ -170,28 +170,45 @@ limited. (However to be fair, it may have only been intended for games
and may be suitable for that). Applications that just want the CD
reading and control portion I think will find quite a bit overhead.
Another related project is J@"org Schilling's SCSI library. If I knew how
to make this project hook into that I'd do it. If you want to
volunteer to undertake, please let me know.
Another related project is J@"org Schilling's SCSI library. You can
use that to make a non-SCSI CD-ROM act like one that understands SCSI
MMC commands which is a neat thing to do. However it is a little weird
to have to install drivers just so you can run a particular user-level
program. Installing drivers often requires special priviledges and
permissions and it is pervasive on a system. It is a little sad that
along the way to creating such a SCSI library a library similar to
@value{libcdio} wasn't created which could be used. Were that the
case, this library certainly never would have been written.
At the OS level there is the "A Linux CD-ROM Standard" by David van
Leeuwen from around 1999. This defines a set of definitions and
ioctl's that mask hardware differences of various Compact Disc
hardware. It is a great idea and no doubt something similar exists on
other platforms. However this "standard" lacked adoption on OS's other
than GNU/Linux.
hardware. It is a great idea, however this ``standard'' lacked
adoption on OS's other than GNU/Linux. (Or maybe it's the case that
the standard on other OS's lacked adoption on GNU/Linux.)
Finally at the hardware level where a similar chaos exists (existed?),
there is the SCSI MMC (multimedia commands). This attempts to provide
a uniform command set for CD devices sort of like PostScript does for
printer commands. But in contrast to PostScript, there is no uniform
PostScript command language that programmers can write to. Instead
each OS has its own ``standard API.'' For example Adaptec's ASPI or
the Microsoft's DeviceIoControl on Microsoft Windows, or IOKit for
Apple's OS/X, or FreeBSD's CAM. Even in situtations where the
underlying function impliment MMC, the way you write code to invoke
the commands is different across OS's. In @value{libcdio} we provide a
common API to issue SCSI-MMC commands.
Finally at the hardware level where a similar chaos exists, there has
been an attempt to do something similar with the SCSI MMC (multimedia
commands). This attempts to provide a uniform command set for CD
devices PostScript does for printer commands.@footnote{I wrote
``attempts'' because over time the command set has changed and now
there are several different commands to do a particular function like
read a CD table of contents and some hardware understands some of the
version of the commands set but might not others} In contrast to
PostScript where there one in theory can write a PostScript program in
a uniform ASCII representation and send that to a printer, for MMC
although there are common internal structures defined, there is no
common syntax for representing the structures or an OS-independent
library or API for issuing MMC-commands which a programmer would need
to use. Instead each Operating System has its own interface. For
example Adaptec's ASPI or the Microsoft's DeviceIoControl on Microsoft
Windows, or IOKit for Apple's OS/X, or FreeBSD's CAM. I've been
postively amazed at how many different variations for doing basically
the same thing there are. And how easy it is to issue an SCSI-MMC
command from a program varies from easy to very difficult. Mastering
the boilerplate code to issue a command on one OS really doesn't help
in figuring out how to do it on another OS. So in @value{libcdio} we
provide a common API to issue SCSI-MMC commands.
@node Purpose
@chapter What is in this package (and what's not)
@@ -995,17 +1012,17 @@ print_cdtext_track_info(CdIo *cdio, track_t i_track, const char *message) @{
@}
static void
print_disc_info(CdIo *cdio, track_t i_tracks, track_t i_first_track) @{
print_disc_info(CdIo *p_cdio, track_t i_tracks, track_t i_first_track) @{
track_t i_last_track = i_first_track+i_tracks;
discmode_t cd_discmode = cdio_get_discmode(cdio);
discmode_t cd_discmode = cdio_get_discmode(p_cdio);
printf("%s\n", discmode2str[cd_discmode]);
print_cdtext_track_info(cdio, 0, "\nCD-TEXT for Disc:");
for ( ; i_first_track < i_last_track; i_first_track++ ) @{
char msg[50];
char psz_msg[50];
sprintf(msg, "CD-TEXT for Track %d:", i_first_track);
print_cdtext_track_info(cdio, i_first_track, msg);
print_cdtext_track_info(p_cdio, i_first_track, psz_msg);
@}
@}
@@ -1014,19 +1031,19 @@ main(int argc, const char *argv[])
@{
track_t i_first_track;
track_t i_tracks;
CdIo *cdio;
CdIo *p_cdio;
cdio = cdio_open (NULL, DRIVER_UNKNOWN);
i_first_track = cdio_get_first_track_num(cdio);
i_tracks = cdio_get_num_tracks(cdio);
i_first_track = cdio_get_first_track_num(p_cdio);
i_tracks = cdio_get_num_tracks(p_cdio);
if (NULL == cdio) @{
if (NULL == p_cdio) @{
printf("Couldn't find CD\n");
return 1;
@} else @{
print_disc_info(cdio, i_tracks, i_first_track);
print_disc_info(p_cdio, i_tracks, i_first_track);
@}
cdio_destroy(cdio);
cdio_destroy(p_cdio);
return 0;
@}