[mythtv] FAO Thor, Metadata question prior to Album Artist repatch.

[thor]

On Tuesday 07 September 2004 02:39 pm, Colin Guthrie wrote:
> Yo,
>
> OK, I've given up any possibility of it being in 0.16!!

	Probably a good idea at his point :-)

>
> I was just thinking about how best to change the lameencoder.cpp file to
> do the tag writing correctly with the TPE4 id3v2 field for album artist
> stuff and wondered if it was worth standardising a little.
>
> The flacencoder.cpp file actually uses the flacdecoder class to
> commitMetadata. (and I've just realised I didn't patch this method for
> my stuff - oops!)
>
> But anyways, maddecoder, avfdecoder and vorbisdecoder do not implement
> their commitMetadata methods.
>
> So here is the question.... should I try and standardise how this works?

	That would be great.

>
> Here is my thoughts on the pros/cons.
>

	Although it is a _bit_ odd to do the write's in a decoder class, the lame vs. 
libid3tag really seems to make it much easier to do it that way. I don't have 
a problem with it.


> To me the last Con above may be the biggie as IIRC you have to rewrite
> the whole file to get a Vorbis Comment into it. Tho' I'm guessing the
> same problem may be true for a Vorbis Comment in a FLAC file??

	Not a biggie. 

>
> What are your thoughts?
>
>
> Oh, and I was thinking that I'll also add a "compilation=0|1" vorbis
> comment field. The problem being, I can't think of a good id3v2 frame to
> indicate the fact it is a compilation. The only one that is close is
> "--TPOS    Part of a set" but this isn't really correct, just the best I
> can get from running "id3v2 -f"
>

	As I understand it, part of the point of id3v2 is that you can add tags in a 
way that won't break other players (those that don't understand the tag). May 
require a little experimentation though. I was going to say that I bet if you 
looked at any mp3 rip from iTunes it would include some sort of Compilation 
tag ... then I thought, why not just rip a Soundtrack to mp3 with iTunes and 
see what it does:

 
id3info 02\ Sparks.mp3

*** Tag information for 02 Sparks.mp3
=== TT2 (Title/songname/content description): Sparks
=== TP1 (Lead performer(s)/Soloist(s)): The Who
=== TCM (Composer): Pete Townshend
=== TAL (Album/Movie/Show title): Almost Famous
=== TRK (Track number/Position in set): 2/17
=== TPA (Part of a set): 1/1
=== TYE (Year): 1969
=== TCO (Content type): (24)
=== TCP ():  frame
=== TEN (Encoded by): iTunes v4.6.0.15
=== COM (Comments): (iTunNORM)[eng]:  000006E5 0000058C 0000462E 00005B47 
00025192 0000AB87 0000843D 00008185 00007178 00007178
=== COM (Comments): (iTunes_CDDB_IDs)[eng]: 
17+1BD15F2476573DD0FED1A1F24244804E+899521
*** mp3 info
MPEG1/layer III
Bitrate: 192KBps
Frequency: 44KHz

	Low and behold, no "Compilation" field. Perhaps we should just add a Comment 
of "compilation: true" or "compilation: false" ?


> As for your last comment about TPE4 not being a "standard" field and
> that easytag etc. wouldn't do anything with it, I agree that this is a
> shortcoming. What I don't understand is how can I be the only person
> that thinks this is a necessary bit of metadata to store??? 

	I hear ya. Rule of thumb at this point is, I think, create all the tags you 
need to accomplish the job, but make them standard whenever and wherever 
there's a standard available.

- thor