Interface to CD-ROM player.

This module implements an interface to the built-in cd module.  The

intention is to provide a more user-friendly interface than the

built-in module.

The module defines a class Readcd with several methods.  The

initialization of the class will try to open the CD player.  This

means that initialization will fail if the CD player is already in

use.  A RuntimeError will be raised by the cd module in that case.

The way to work with this module is as follows.  The user specifies

the parts of the CD that are to be read and he specifies callback

functions which are to be called by the system.  At some point he can

tell the system to play.  The specified parts of the CD will then be

read and the callbacks will be called.

Initialization.

===============

r = readcd.Readcd([cd-player [, mode]])

The optional arguments are the name of the CD device and the mode.

When "mode" is not specified, it defaults to 'r' (which is the only

possible value); when "cd-player" also isn't specified, it defaults

to "None" which indicates the default CD player.

Methods.

========

eject() -- Eject the CD from the player.

reset() -- Reset the list of data stretches to be played.

appendtrack(track) -- Append the specified track to the list of music

stretches.

appendstretch(first, last) -- Append the stretch from "first" to "last"

to the list of music stretches.  Both "first" and "last" can be in one

of four forms.  "None": for "first", the beginning of the CD, for

"last" the end of the CD; a single integer: a track number--playing

starts at the beginning of the track or ends at the end of the

specified track; a three-tuple: the absolute time from the start of

the CD in minutes, seconds, frames; a four-tuple: track number and

relative time within the track in minutes, seconds, frames.

settracks(tracklist) -- The argument is a list of integers.  The list

of stretches is set to argument list.  The old list is discarded.

setcallback(type, func, arg) -- Set a callback function for "type".

The function will be called as func(arg, type, data) where "arg" is

the third argument of setcallback, "type" is the type of callback,

"data" is type-dependent data.  See the CDsetcallback(3) manual page

for more information.  The possible "type" arguments are defined in

the CD module.

removecallback(type) -- Remove the callback for "type".

gettrackinfo([tracklist]) -- Return a list of tuples.  Each tuple

consists of start and length information of a track.  The start and

length information consist of three-tuples with minutes, seconds and

frames.  The optional tracklist argument gives a list of interesting

track numbers.  If no tracklist is specified, information about all

tracks is returned.

getstatus() -- Return the status information of the CD.

play() -- Play the preprogrammed stretches of music from the CD.  When

nothing was programmed, the whole CD is played.

Specifying stretches.

=====================

There are three methods available to specify a stretch of music to be

played.  The easiest way is to use "settracklist(tracklist)" with which

a list of tracks can be specified.  "settracklist(tracklist)" is

equivalent to the sequence

	reset()

	for track in tracklist:

		appendtrack(track)

The next method is "appendtrack(track)" with which a whole track can be

added to the list of music to be played.  "appendtrack(track)" is

equivalent to "appendstretch(track, track)".

The most complete method is "appendstretch(first, last)".  Using this

method, it is possible to specify any stretch of music.

When two consecutive tracks are played, it is possible to choose

whether the pause that may be between the tracks is played as well or

whether the pause should be skipped.  When the end of a stretch is

specified using a track number and the next stretch starts at the

beginning of the following track and that was also specified using the

track number (that is, both were specified as integers, not as tuples),

the pause is played.  When either value was specified using absolute

time or track-relative time (that is, as three-tuple or as

four-tuple), the pause will not be played.

Errors.

=======

When an error occurs, an exception will be raised.  Depending on where

the error occurs, the exception may either be "readcd.Error" or

"RuntimeError".