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Tiago Cogumbreiro

O Irrepupável

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How to get an Audio-CD tracks count

The Problem

I want to add a new feature to serpentine: copy an audio-cd

I have found 5 solutions: sound juicer, cdrecord, musicbrainz, pygame and cddb.

sound juicer

One way of issuing sound juicer commands would be to do the following: set the following gconf keys (located under /apps/sound-juicer) 

  audio_profile = cdlossless (voice gives a stupid error about gstreamer)
  eject = True
  base_path = /tmp
  device = /dev/cdrom
  file_pattern = %t
  path_pattern = ""

Then we should just:

  • sound-juicer -a
  • convert each track to wav
  • remove the original .flacs
  • write cd
  • remove tracks

cdrecord

To get the number of tracks via cdrecord: 

  cdrecord -toc dev=/dev/cdrom 2> /dev/null  | grep ^first:

musicbrainz

With musicbrainz, on ubuntu, MBE_TOCGetCDIndexID wasn't working, probably because there wasn't ctypes installed 

  >>> import musicbrainz
  >>> mb = musicbrainz.mb ()
  >>> mb.SetDepth (2)
  >>> q = musicbrainz
  >>> mb.Query (q.MBQ_GetCDTOC)
  >>> cdid = str (mb.GetResultData (q.MBE_TOCGetCDIndexID))
  >>> mb.QueryWithArgs(q.MBQ_GetCDInfoFromCDIndexId, [cdid])
  >>> mb.GetResultInt(q.MBE_GetNumAlbums)
  1
  >>> mb.Select1(q.MBS_SelectAlbum, 1)
  1
  >>> mb.GetResultInt(q.MBE_AlbumGetNumTracks)
  12

pygame

Here's how to do it with PyGame: 

  >>> import pygame.cdrom
  >>> pygame.cdrom.init ()
  >>> cd = pygame.cdrom.CD (0)
  >>> cd.init ()
  >>> cd.get_numtracks ()
  12
  >>> cd.get_id ()
  0
  >>> cd.get_name ()
  '/dev/cdrom'

CDDB

CDDB (the python module):

This is actually a set of three modules to access the CDDB and FreeDB online databases of audio CD track titles and information. It includes a C extension module to fetch track lengths under Linux, FreeBSD, OpenBSD, Mac OS X, Solaris, and Win32, which is easily ported to other operating systems. 

  >>> import DiscID
  >>> d = DiscID.open()
  >>> did = DiscID.disc_id (d)
  >>> did[1]
  12

Conclusion

I think that CDDB is the most appropriate way of doing it, since it's a really lightweight dependency and should be available in all systems. It has a GPL, but there are already lots of GUI parts of serpentine that are GPL'ed (because of nautilusburn).

I would like for this feature to be implemented as a plugin, it would prove as a very good example on the possibilities and ways of doing plugins. It could also mean some refactoring, which is always good.

TODO

Find a way to dynamicaly add elements to the menu system.

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