Unable to handle Musicbrainz releases with multiple discs properly

[Eike Thaden]

Musicbrainz allows to use releases with multiple discs (no separate releases for disc 1, disc 2, and so on). Unfortunately this feature is not yet supported by the musicbrainz3 libraries which are currently used by libkcddb (up to KDE 4.8.x). With musicbrainz3, importing a release with multiple discs results in one huge track list containing all the tracks of all discs. soundkonverter does not know about that and chooses the first n tracks (where n is the number of audio tracks on the current disc).

I found no way to identify which tracks in the release belong to the currently inserted disc. This bug will probably disappear as soon as KDE 4.9 is released (which uses musicbrainz4 libs).

Therefore I wrote a little workaround which allows the user to choose the first track of the current disc out of the the list of all tracks returned by libkcddb. The dialog will only appear if more tracks are returned by libkcddb then found on the physical disc.

Warning: Before using this patch please add checks for the boundaries of the array (e.g. a user might choose the last entry of the track list leading to a out-of-bound issue if that disc has more than one track).

[Daniel Faust (hessijames)]

Thanks for the patch.
Could you tell me how you tested it?

[Eike Thaden (ethaden)]

You are welcome.

"Testing" was simple: I love classical music and buy new CDs regularly. In many cases there is no musicbrainz release yet (maybe most users do not like classical music?). I add a new release then. Most times my records consists of multiple discs which are assigned to the same release. The last opera I added was "Götterdämmerung" by Richard Wagner, see
http://musicbrainz.org/release/cafaa097-acdf-4311-9171-81a6fefd423f

The release consists of four discs each with a unique disc id attached.

If you want to test the patch: Search for a multi disc album in your CD shelf. Check whether or not it is already known to Musicbrainz (I'm using "picard" for that purpose). If there is a release already check that this release really consists of more than one disc (some users create multiple releases, one for each disc. This is not how it should be done!). If all discs are correctly assigned to the same release, you have your test candidate. If not, try another album. If your album is not yet known to Musicbrainz, I suggest you simply create a new release. :-)

Try to rip on of the discs with soundkonverter. Here the patch now checks for situations where libkcddb returns more tracks than available on the physical disc. That's the only way to identify multi disc releases (as long as libkcddb relies on the deprecated musicbrainz library version). The selection box should show up and you can select the first entry of the current disc by hand.

I hope this helps. :-)

[Daniel Faust (hessijames)]

I haven't found many multi disc albums and pretty much all of them can be found as single disc releases. So libkcddb prefers the single disc releases and the multi disc releases won't get shown in the soundkonverter release selection dialog.

I have an album though that couldn't be found on musicbrainz. When I tried to add it, I saw that it was already added to musicbrainz but without disc ids. So I thought I might be able to merge those two releases and then add the disc ids.
What do you think?
http://musicbrainz.org/release-group/f2c42746-a70c-44b2-b53b-d15e07976124

So that made me think. Does libkcddb return the multi disc release for you if the disc id matches one of those in the release. Because then, as I wrote above, libkcddb/libmusicbrainz/whoever seems to drop the multi disc release if a single disc release was found.

[Eike Thaden (ethaden)]

Hm, I think for all multi disc albums I had issues with one of the following applies:
1. The disc IDs of all discs belonging have been assigned to the same release (and not to any other release)
2. The disc IDs were not known to Musibrainz

In fact, for a small number of my multi disc albums I found multiple releases, one per disc. For those albums soundkonverter works out-of-the-box.

But I think this is not how multi disc releases are meant to be organized in Musicbrainz, see http://musicbrainz.org/doc/Release for reference.

Regarding your Maria Callas album: According to the lin above, everything depends on how the album has been entitled. I assume that there "(disc 2)" string in the title. Maybe the disc's data has been imported from freedb, which has no concept of "release" at all. I would attach the corresponding disc IDs to the releases and then merge them. It will take some time for your changes to be reviewed (at least that happened to me). After your changes are accepted, you should have an album for testing the software (and you helped to improve the Musicbrainz database :-) )

[Daniel Faust (hessijames)]

Ok, my merge request was accepted so now I have a good test setup.
I tried it without your patch and it works out of the box. As you already suspected in the bug description, KDE 4.9 seems to solve this issue.

I'm running KDE 4.9.2

[Daniel Faust (hessijames)]

Hi Eike,

do you have any news on this?
Otherwise I will have to close this bug report.

[Eike Thaden (ethaden)]

Hello Daniel,

everything works fine since I upgraded to Ubuntu 12.10.

Theres only one feature I don't like: Instead of using the name of the
release directly, the disc number is appended in brackets, such as "
(disc 1)".
I would suggest to leave the name of the release unchanged and set the
disc id attribute correctly instead.

However, I guess this is due to the implementation of the underlying kde
cddb libs (?)

Best regards
 Eike

Am 31.01.2013 15:36, schrieb Daniel Faust:
> Hi Eike,
>
> do you have any news on this?
> Otherwise I will have to close this bug report.
>

[Daniel Faust (hessijames)]

Yes, that's done by libkcddb.
Depending on how important you think it is, you might want to open a bug report at https://bugs.kde.org