| CDDB(3pm) | User Contributed Perl Documentation | CDDB(3pm) |
CDDB.pm - a high-level interface to cddb protocol servers (freedb and CDDB)
version 1.222
use CDDB;
### Connect to the cddbp server.
my $cddbp = new CDDB(
Host => 'freedb.freedb.org', # default
Port => 8880, # default
Login => $login_id, # defaults to %ENV's
) or die $!;
### Retrieve known genres.
my @genres = $cddbp->get_genres();
### Calculate cddbp ID based on MSF info.
my @toc = (
'1 0 2 37', # track, CD-i MSF (space-delimited)
'999 1 38 17', # lead-out track MSF
'1000 0 0 Error!', # error track (don't include if ok)
);
my (
$cddbp_id, # used for further cddbp queries
$track_numbers, # padded with 0's (for convenience)
$track_lengths, # length of each track, in MM:SS format
$track_offsets, # absolute offsets (used for further cddbp queries)
$total_seconds # total play time, in seconds (for cddbp queries)
) = $cddbp->calculate_id(@toc);
### Query discs based on cddbp ID and other information.
my @discs = $cddbp->get_discs($cddbp_id, $track_offsets, $total_seconds);
foreach my $disc (@discs) {
my ($genre, $cddbp_id, $title) = @$disc;
}
### Query disc details (usually done with get_discs() information).
my $disc_info = $cddbp->get_disc_details($genre, $cddbp_id);
my $disc_time = $disc_info->{'disc length'};
my $disc_id = $disc_info->{discid};
my $disc_title = $disc_info->{dtitle};
my @track_offsets = @{$disc_info->{offsets}};
my @track_seconds = @{$disc_info->{seconds}};
my @track_titles = @{$disc_info->{ttitles}};
# other information may be returned... explore!
### Submit a disc via e-mail. (Requires MailTools)
die "can't submit a disc (no mail modules; see README)"
unless $cddbp->can_submit_disc();
# These are useful for prompting the user to fix defaults:
print "I will send mail through: ", $cddbp->get_mail_host(), "\n";
print "I assume your e-mail address is: ", $cddbp->get_mail_address(), "\n";
# Actually submit a disc record.
$cddbp->submit_disc(
Genre => 'classical',
Id => 'b811a20c',
Artist => 'Various',
DiscTitle => 'Cartoon Classics',
Offsets => $disc_info->{offsets}, # array reference
TrackTitles => $disc_info->{ttitles}, # array reference
From => 'login@host.domain.etc', # will try to determine
);
CDDB protocol (cddbp) servers provide compact disc information for programs that need it. This allows such programs to display disc and track titles automatically, and it provides extended information like liner notes and lyrics.
This module provides a high-level Perl interface to cddbp servers. With it, a Perl program can identify and possibly gather details about a CD based on its "table of contents" (the disc's track times and offsets).
Disc details have been useful for generating CD catalogs, naming mp3 files, printing CD liners, or even just playing discs in an automated jukebox.
Despite the module's name, it connects to FreeDB servers by default. This began at version 1.04, when cddb.com changed its licensing model to support end-user applications, not third-party libraries. Connections to cddb.com may still work, and patches are welcome to maintain that functionality, but it's no longer officially supported.
The interface will not actually connect to a cddbp server until it's used, and a single cddbp interface may actually make several connections (to possibly several servers) over the course of its use.
The new() constructor accepts several parameters, all of which have reasonable defaults.
Host and Port describe the cddbp server to connect to. These default to 'freedb.freedb.org' and 8880, which is a multiplexor for all the other freedb servers.
Utf8 is a boolean flag. If true, utf-8 will be used when submitting CD info, and for interpreting the data reveived. This requires the Encode module (and probably perl version at least 5.8.0). The default is true if the Encode module can be loaded. Otherwise, it will be false, meaning we fall back to ASCII.
Protocol_Version sets the cddbp version to use. CDDB.pm will not connect to servers that don't support the version specified here. The requested protocol version defaults to 1 if Utf8 is off, and to 6 if it is on.
Login is the login ID you want to advertise to the cddbp server. It defaults to the login ID your computer assigns you, if that can be determined. The default login ID is determined by the presence of a LOGNAME or USER environment variable, or by the getpwuid() function. On Windows systems, it defaults to "win32usr" if no default method can be found and no Login parameter is set.
Submit_Address is the e-mail address where new disc submissions go. This defaults to 'freedb-submit@freedb.org'. Note, that testing submissions should be done via "test-submit@freedb.org".
Client_Name and Client_Version describe the client software used to connect to the cddbp server. They default to 'CDDB.pm' and CDDB.pm's version number. If developers change this, please consult freedb's web site for a list of client names already in use.
Debug enables verbose operational information on STDERR when set to true. It's normally not needed, but it can help explain why a program is failing. If someone finds a reproduceable bug, the Debug output and a test program would be a big help towards having it fixed. In case of submission, if this flag is on, a copy of the submission e-mail will be sent to the From address.
Note however that there is no standard way to acquire this information from a CD-ROM device. Therefore this module does not try to read the TOC itself. Instead, developers must combine CDDB.pm with a CD library which works with their system. The AudioCD suite of modules is recommended: it has system specific code for MacOS, Linux and FreeBSD. CDDB.pm's author has used external programs like dagrab to fetch the offsets. Actual CDs aren't always necessary: the author has heard of people generating TOC information from mp3 file lengths.
That said, see parse_cdinfo() for a routine to parse "cdinfo" output into a table of contents list suitable for calculate_id().
calculate_id() accepts TOC information as a list of strings. Each string contains four fields, separated by whitespace:
offset 0: the track number
Track numbers start with 1 and run sequentially through the number of tracks on a disc. Note: data tracks count on hybrid audio/data CDs.
CDDB.pm understands two special track numbers. Track 999 holds the lead-out information, which is required by the cddb protocol. Track 1000 holds information about errors which have occurred while physically reading the disc.
offset 1: the track start time, minutes field
Tracks are often addressed on audio CDs using "MSF" offsets. This stands for Minutes, Seconds, and Frames (fractions of a second). The combination pinpoints the exact disc frame where a song starts.
Field 1 contains the M part of MSF. It is ignored for error tracks, but it still must contain a number. Zero is suggested.
offset 2: the track start time, seconds field
This field contains the S part of MSF. It is ignored for error tracks, but it still must contain a number. Zero is suggested.
offset 3: the track start time, frames field
This field contains the F part of MSF. For error tracks, it contains a description of the error.
Example track file. Note: the comments should not appear in the file.
1 0 2 37 # track 1 starts at 00:02 and 37 frames
2 1 38 17 # track 2 starts at 01:38 and 17 frames
3 11 57 30 # track 3 starts at 11:57 and 30 frames
...
999 75 16 5 # leadout starts at 75:16 and 5 frames
Track 1000 should not be present if everything is okay:
1000 0 0 Error reading TOC: no disc in drive
In scalar context, calculate_id() returns just the cddbp ID. In a list context, it returns an array containing the following values:
(
$cddbp_id,
$track_numbers,
$track_lengths,
$track_offsets,
$total_seconds
) = $cddbp->calculate_id(@toc);
print(
"cddbp ID = $cddbp_id\n", # b811a20c
"track numbers = @$track_numbers\n", # 001 002 003 ...
"track lengths = @$track_lengths\n", # 01:36 10:19 04:29 ...
"track offsets = @$track_offsets\n", # 187 7367 53805 ...
"total seconds = $total_seconds\n", # 4514
);
CDDBP_ID
The 0th returned value is the hashed cddbp ID, required for any queries or submissions involving this disc.
TRACK_NUMBERS
The 1st returned value is a reference to a list of track numbers, one for each track (excluding the lead-out), padded to three characters with leading zeroes. These values are provided for convenience, but they are not required by cddbp servers.
TRACK_LENGTHS
The 2nd returned value is a reference to a list of track lengths, one for each track (excluding the lead-out), in HH:MM format. These values are returned as a convenience. They are not required by cddbp servers.
TRACK_OFFSETS
The 3rd returned value is a reference to a list of absolute track offsets, in frames. They are calculated from the MSF values, and they are required by get_discs() and submit_disc().
TOTAL_SECONDS
The 4th and final value is the total playing time for the CD, in seconds. The get_discs() function needs it.
my @id_info = $cddbp->calculate_id(@toc);
my $cddbp_id = $id_info->[0];
my $track_offsets = $id_info->[3];
my $total_seconds = $id_info->[4];
get_discs() returns an array of matching discs, each of which is represented by an array reference. It returns an empty array if the query succeeded but did not match, and it returns undef on error.
my @discs = $cddbp->get_discs( $cddbp_id, $track_offsets, $total_seconds );
foreach my $disc (@discs) {
my ($disc_genre, $disc_id, $disc_title) = @$disc;
print(
"disc id = $disc_id\n",
"disc genre = $disc_genre\n",
"disc title = $disc_title\n",
);
}
DISC_GENRE is the genre this disc falls into, as determined by whoever submitted or last edited the disc. The genre is required when requesting a disc's details. See get_genres() for how to retrieve a list of cddbp genres.
CDDBP_ID is the cddbp ID of this disc. Cddbp servers perform fuzzy matches, returning near misses as well as direct hits on a cddbp ID, so knowing the exact ID for a disc is important when submitting changes or requesting a particular near-miss' details.
DISC_TITLE is the disc's title, which may help a human to pick the correct disc out of several close mathches.
Cddb protocol query strings look like:
cddb query $cddbp_id $track_count @offsets $total_seconds
The disc's details are returned in a reference to a fairly complex hash. It includes information normally stored in comments. The most common entries in this hash include:
$disc_details = get_disc_details( $disc_genre, $cddbp_id );
$disc_details->{"disc length"}
The disc length is commonly stored in the form "### seconds", where ### is the disc's total playing time in seconds. It may hold other time formats.
$disc_details->{discid}
This is a rehash (get it?) of the cddbp ID. It should match the CDDBP_ID given to get_disc_details().
$disc_details->{dtitle}
This is the disc's title. I do not know whether it will match the one returned by get_discs().
$disc_details->{offsets}
This is a reference to a list of absolute disc track offsets, similar to the TRACK_OFFSETS returned by calculate_id().
$disc_details->{seconds}
This is a reference to a list of track length, in seconds.
$disc_details->{ttitles}
This is a reference to a list of track titles. These are the droids you are looking for.
$disc_details->{"processed by"}
This is a comment field identifying the name and version of the cddbp server which accepted and entered the disc record into the database.
$disc_details->{revision}
This is the disc record's version number, used as a sanity check (semaphore?) to prevent simultaneous revisions. Revisions start at 0 for new submissions and are incremented for every correction. It is the responsibility of the submitter (be it a person or a program using CDDB.pm) to provide a correct revision number.
$disc_details->{"submitted via"}
This is the name and version of the software that submitted this cddbp record. The main intention is to identify records that are submitted by broken software so they can be purged or corrected.
$disc_details->{xmcd_record}
The xmcd_record field contains a copy of the entire unprocessed cddbp response that generated all the other fields.
$disc_details->{genre}
This is merely a copy of DISC_GENRE, since it's otherwise not possible to determine it from the hash.
my $mail_from = $cddb->get_mail_address();
print "New e-mail address (or blank to keep <$mail_from>): ";
my $new_mail_from = <STDIN>;
$new_mail_from =~ s/^\s+//;
$new_mail_from =~ s/\s+$//;
$new_mail_from =~ s/\s+/ /g;
$mail_from = $new_mail_from if length $new_mail_from;
$cddbp->submit_disc(
...,
From => $mail_from,
);
my $mail_host = $cddb->get_mail_host();
print "New e-mail host (or blank to keep <$mail_host>): ";
my $new_mail_host = <STDIN>;
$new_mail_host =~ s/^\s+//;
$new_mail_host =~ s/\s+$//;
$new_mail_host =~ s/\s+/ /g;
$mail_host = $new_mail_host if length $new_mail_host;
$cddbp->submit_disc(
...,
Host => $mail_host,
);
my @toc = parse_cdinfo("cdinfo.txt"); # read cdinfo.txt
my @toc = parse_cdinfo("cdinfo|"); # run cdinfo directly
The table of contents can be passed directly to calculate_id().
The rest of CDDB.pm will work without the ability to submit discs. While cddbp submissions are relatively rare, most CD collections will have one or two discs not present in the system. Please submit new discs to the system: the amazing number of existing discs got there because others submitted them before you needed them.
submit_disc() takes six required parameters and two optional ones. The parameters are named, like hash elements, and can appear in any order.
Genre => DISC_GENRE
This is the disc's genre. It must be one of the genres that the server knows. See get_genres().
Id => CDDBP_ID
This is the cddbp ID that identifies the disc. It should come from calculate_id() if this is a new submission, or from get_disc_details() if this is a revision.
Artist => DISC_ARTIST
This is the disc's artist, a freeform text field describing the party responsible for the album. It will need to be entered from the disc's notes for new submissions, or it can come from get_disc_details() on subsequent revisions.
DiscTitle => DISC_TITLE
This is the disc's title, a freeform text field describing the album. It must be entered from the disc's notes for new submissions. It can come from get_disc_details() on subsequent revisions.
Offsets => TRACK_OFFSETS
This is a reference to an array of absolute track offsets, as provided by calculate_id().
TrackTitles => TRACK_TITLES
This is a reference to an array of track titles, either entered by a human or provided by get_disc_details().
From => EMAIL_ADDRESS
This is the disc submitter's e-mail address. It's not required, and CDDB.pm will try to figure one out on its own if an address is omitted. It may be more reliable to provide your own, however.
The default return address may not be a deliverable one, especially if CDDB.pm is being used on a dial-up machine that isn't running its own MTA. If the current machine has its own MTA, problems still may occur if the machine's Internet address changes.
Host => SMTP_HOST
This is the SMTP host to contact when sending mail. It's not required, and CDDB.pm will try to figure one out on its own. It will look at the SMTPHOSTS environment variable is not defined, it will try 'mail' and 'localhost' before finally failing.
Revision => REVISION
The revision number. Should be 1 for new submissions, and one higher than the previous one for updates. The previous revision number is available as the "revision" field in the hash returned by get_disc_details().
Documented as being not documented.
Please see the cddb.t program in the t (tests) directory. It exercises every aspect of CDDB.pm, including submissions.
CDDB.pm uses standard Perl modules. It has been tested at one point or another on OS/2, MacOS and FreeBSD systems, as well as the systems listed at:
http://testers.cpan.org/search?request=dist&dist=CDDB
If you want to submit disc information to the CDDB, you will need to install two other modules:
Mail::Internet will allow CDDB.pm to send email submissions, and it automagically includes Mail::Header. MIME::QuotedPrint will allow CDDB.pm to send non-ASCII text unscathed. Currently only ISO-8859-1 and ASCII are supported.
All other features will work without these modules.
The last test in the "make test" suite will try to send a sample submission to the CDDB if MailTools is present. It expects to find an SMTP host in the SMTPHOST environment variable. It will fall back to "mail" if SMTPHOST doesn't exist. If neither works, the test will be skipped. To see why it's skipped:
make test TEST_VERBOSE=1
Some of the tests (most notably numbers 25, 27 and 29) compare data returned by a cddbp server against a stored copy of a previous query. These tests fail occasionally since the database is constantly in flux. Starting with version 1.00, the test program uses fuzzy comparisons that should fail less. Version 1.04 saw even fuzzier comparisons. Please report any problems so they can be fixed.
https://rt.cpan.org/Dist/Display.html?Status=Active&Queue=CDDB
http://github.com/rcaputo/cddb-perl http://gitorious.org/cddb-freedb-perl
http://search.cpan.org/dist/CDDB/
Copyright 1998-2013 Rocco Caputo. All rights reserved. This program is free software; you can redistribute it and/or modify it under the same terms as Perl itself.
| 2013-08-15 | perl v5.18.1 |