ATF safety

[Jeff Mitchell]

Quoting Colin Guthrie <gmane at colin.guthr.ie>:

> Cool. From what I've read it is quite a sneaky thread based problem that
> are often very hard to spot and to be affected by, so I guess it's not
> surprising that it works fine for most people.

It was actually an inter-process problem, although I don't know if  
that made things worse or not.  I do know some conditions as to when  
corruption could definitely occur, mostly related to a condition that  
could arrise whereby two collection scanners could be running at once.

> Cool. Does that mean it will be unavailable in 1.4.2 or just disabled by
> default?

It will be available if people want it, but they'd have to enable it  
manually in amarokrc.  I wouldn't recommend it, since one of the  
important fixes (not letting two collectionscanners run at once) won't  
be put in until after 1.4.2 since we don't have time to really test it  
out beforehand.

This fix will go into SVN soon after 1.4.2 though, after which time  
the GUI option will be re-enabled, with an extra warning.

> More out of curiosity rather than any overwhelming desire to
> protect people from the problem ;) I know about and I wont turn it on
> until people say it's OK (and I just so happened to backup my music onto
> an old HD this morning so I guess I could do a full scan/tag happily
> anwyay ;))

That would be really great.  Especially if you have enough space to do  
some repeat testing, i.e. copy from your backup to your HD, do some  
testing, blow away the new copy, and recopy, do some more testing,  
etc.  There are a couple specific things that it'd be good to test,  
and if you're running SVN, I may ask you to test with a few different  
revisions.

> Actually, when I'm hear and while it's not too off topic, say I have an
> MP3 player (my phone) and I want to re-encode some Oggs and high bitrate
> MP3s to lower quality for it and setup Amarok to do this automatically
> (not looked at this yet but I remember there was some scripts to do this
> in the past), will it preserve the ATF ID (and indeed, should it preserv
> the ATF ID)?

No, it won't, and it probably shouldn't either.  Transcoding between  
different bitrates of the same format should theoretically work, if  
the transcoding app copies all tags, but between different formats  
will not work.

> Also will it prefer my higher quality originals to the
> lower quality versions? Not really thought this question through
> really... just some thoughts from the top of my head.

It doesn't have a preference really.  If it sees that you have two  
files with the same UID it will attempt to give one of them a new one.  
  Having it check bitrates et al is probably not a good idea because  
we can't know ahead of time what any specific user will want.   
Actually, in general the assumption is that if you have two copies of  
a song at different bitrates, you'll delete one of them anyways :-)

--Jeff