Which format is chosen for embedded coverart?

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TomBK
Posts: 14
Joined: Mon Feb 23, 2009 8:31 pm

Which format is chosen for embedded coverart?

Post by TomBK » Mon Feb 23, 2009 9:13 pm

Hi sbooth

Just out of curiousity: Why does the "Save album art with output files" only affect album art that is being downloaded and not the album art embedded to eg. flac files? The embedded seems to be .png whatever format is chosen. Is this due to size and the .png is the smallest file that can be embedded? Is actually keen to get a real tech explanation to how this is done as albumart seems to be a forever existing issue. A url will do if this otherwise would take forever to explain :wink:

PS: Only trying to steal your knowledge - not copy your software :D
ADS/D/Cara1 • KK/1/D • 5103 • 2 Solos • 242s/quinwired k600+k400 • Center: Klout/Ekwal aktiv • Linn silver ics • Readynas Duo/Twonky 5.0.68
Bits & bobs listed elsewhere...;-) But I'm on a Mac...

Mike1
Posts: 201
Joined: Thu Sep 21, 2006 3:55 pm

Re: Which format is chosen for embedded coverart?

Post by Mike1 » Mon Feb 23, 2009 11:22 pm

TomBK wrote:The embedded seems to be .png whatever format is chosen.
I'd noticed that, too. I assume any image format is OK, because there's provision for stating a MIME-type for imbedded album art in FLAC. I know that because the field was involved in a security issue in the past once:
Vulnerability #4: Picture MIME-Type Size Heap Overflow
The Picture Metadata block allows the insertion of a MIME-Type for the embedded album art in a FLAC file. This field is vulnerable to a heap-based overflow when applications that support FLAC album art attempt to process an overly large MIME-TYPE Size field. Again arbitrary code execution depends on the location of the overwritten memory, the vulnerable programs exception handling, structure of the heap at the time of the overflow, and the ability to process Picture Data within FLAC files.
http://research.eeye.com/html/advisorie ... 71115.html

You can see the format spec here:

http://flac.sourceforge.net/format.html

and the metadata_block_picture specifically here:

http://flac.sourceforge.net/format.html ... ck_picture

Maybe Stephen is choosing PNGs for compatibility. The FLAC site says:
MIME-TYPE is optional; if left blank, it will be detected from the file. For best compatibility with players, use pictures with MIME type image/jpeg or image/png. The MIME type can also be --> to mean that FILE is actually a URL to an image, though this use is discouraged.

[My italics]
http://flac.sourceforge.net/documentati ... _flac.html

TomBK
Posts: 14
Joined: Mon Feb 23, 2009 8:31 pm

Re: Which format is chosen for embedded coverart?

Post by TomBK » Tue Feb 24, 2009 1:05 am

Thanks a bunch for the urls, Mike :D

Trying to broaden my horizons here and this stuff is great!

What I'm looking for(if possible) is an explanation to why Twonky won't show album art if it's ripped and embedded in the flac files but only shows the art when it's placed as a single image file(Folder.jpg) in the Album folder with no art embedded in the flac files.

Maybe the embedding with .png explains why, cause Twonky only accepts .jpg as image format/suffix in order to show album art.

Unfortunately this is not something to test as an end user...

I'm not going about this very scientifically and haven't tried other ripping software yet being satisfied with Max so far.

Just being curious now...
ADS/D/Cara1 • KK/1/D • 5103 • 2 Solos • 242s/quinwired k600+k400 • Center: Klout/Ekwal aktiv • Linn silver ics • Readynas Duo/Twonky 5.0.68
Bits & bobs listed elsewhere...;-) But I'm on a Mac...

Mike1
Posts: 201
Joined: Thu Sep 21, 2006 3:55 pm

Re: Which format is chosen for embedded coverart?

Post by Mike1 » Tue Feb 24, 2009 12:06 pm

TomBK wrote: Maybe the embedding with .png explains why, cause Twonky only accepts .jpg as image format/suffix in order to show album art.
Sounds like it, then.

It's unfortunate - my guess would be PNG was chosen, because the FLAC site advises to use JPEG or PNG on account of compatibility. But from what you're saying it seems there's stuff that's not compatible with PNG.
I'm not going about this very scientifically and haven't tried other ripping software yet being satisfied with Max so far.
I suppose the alternatives - unless you get into MacPorts or virtualization software - are iTunes and XLD (X Lossless Decoder). But you can't encode to FLAC with iTunes. If you want FLAC the choices are limited on OS X.

I don't know what Max does to the art if you rip and encode to Apple Lossless in iTunes and then convert to FLAC in Max. But that would be a long way round, anyway.

Or the thought occurs that you could rip and encode in Max and add the album art with a separate tagger. But, again, the options are limited on OS X. The last I looked Media Rage could, if I'm remembering right, add images to FLACs but only one file at a time, not as a batch like it can with MP3s. You might try their tagging software and email them if it doesn't do quite what you're looking for. They seem very responsive to customer feedback - I suppose they have to be if they want to stay on top of their market.

I'm thinking that while FLAC is quite well supported across platforms, it's not of any particular interest to many Mac users, so there's enough software to be going on with but not quite full coverage of everything you might want to do. I suppose iTunes in general does so much of what most people want, and more, and does it so well, that most Mac users just accommodate themselves to it. Here, this would mean they use Apple Lossless instead of FLAC.

Sorry. All I can think of is try XLD or rip with Max but try tagging with Media Rage.

It may be possible to add a JPEG at the commandline, but I haven't looked into what commandline tools a user would have to compile/install for that.

Maybe someone more knowledgeable than I would have better advice, but these boards seem very quiet at present.

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