You said "With the exception of where to put a picture file, VorbisComments
in a Vorbis stream are the same as VorbisComments in a FLAC stream."
In METADATA_BLOCK_PICTURE case they would not be the same. Up to now we
could exchange the complete block of VorbisComments. But with the addiction
of METADATA_BLOCK_PICTURE doesn't happen this way.
In Ogg files the METADATA_BLOCK_PICTURE data are split in numerous pieces,
each one of them with a Oggs header (44 up to 282 bytes of non Base64 data
among each piece). Just as they are written would be impossible to put them
in the block 4 of Flac Metadata.
But the specifications are only for Ogg files. For Flac is not specified if
the data, after METADATA_BLOCK_PICTURE=, would be a long string of Base64
format (without split) or otherwise. It seems that the decision is of Ogg
team and Flac team has not said anything on this matter.
I thought I could choose among both forms of inserting a picture. But
thinking it well, the decision is made because of the silence of Flac. Flac
will continue using the block 6. And in METADATA_BLOCK_PICTURE case,
VorbisComments are not compatible. I continue thinking that to have two
different blocks for this is very bad design.
Regards. Santiago
----- Original Message -----
From: "Martin Leese" <martin.leese at stanfordalumni.org>
To: "Santiago Jimeno" <sjimeno at ya.com>
Sent: Friday, January 21, 2011 7:01 PM
Subject: Re: [Flac] Flac] Where Cover Art?
> On 1/21/11, Santiago Jimeno <sjimeno at ya.com> wrote:
>> Thank you Martin for your answer.
>>
>> Regarding the COVERARTMIME name, I found this entry in ExifTool:
>>
http://www.sno.phy.queensu.ca/~phil/exiftool/TagNames/Vorbis.html#Comments
>> I suppose that it would be useful to enlarge the information of which
>> COVERART lacked.
>
> Hi Santiago,
>
> As the webpage you cite states, "The tags [on
> the page] are only some common tags found
> in the Vorbis comments of Ogg Vorbis and
> Ogg FLAC audio files". This list is not official.
> I have never seen COVERARTMIME used
> anywhere else and, as COVERART is going
> away, I would not recommend its use.
>
> The official list of tag names is in the Vorbis
> documentation, and consists of only 15 tags.
> There are also several lists of suggestions for
> other tag names here:
> https://wiki.xiph.org/VorbisComment#Proposed_field_names
>
>> To change the code to use METADATA_BLOCK_PICTURE is simple, since
>> COVERART
>> also wrote in Base64. The result continues being the same handling
>> easiness
>> of Vorbis Comments.
>>
>> But in the FLAC case the problem continues existing. When I spoke of
>> error,
>> I referred to try editing (adding or removing comments or pictures,
>> writing
>> besides reading) in two different blocks at the same time. We can call
it
>> error, ambiguous or otherwise. But, have you tried to write code to
>> maintain
>> this double localization in a simultaneous way?
>
> As I explained, you don't put the same picture
> file in two places. You put it in only one place.
> You get to choose where you put it, either in
> a VorbisComment or in a FLAC
> METADATA_BLOCK. What is needed is some
> official advice on which of these two locations
> is the preferred place to put a picture.
>
> ...
>> In LYRICS case, also "needs to be some official guidance."
It's possibly
>> not
>> very utilized, but it's used. But I cannot invent a Comment name,
>> although
>> this you suggest could be the most appropriate. If somebody that works
in
>> Vorbis Proposal reads this that takes note of the suggestion.
>
> Many, many tags are used. People invent new
> tag names all the time. The Xiph community
> will never produce an exhaustive list. The
> official list will always be a short list of
> commonly used tag names. It will always be
> permitted for others to invent new tag names.
>
>> In any event, if we want Vorbis comments have the same success in FLAC
>> like
>> in OGG, we need clear, simple and mainly effective official norms.
>
> With the exception of where to put a picture
> file, VorbisComments in a Vorbis stream are
> the same as VorbisComments in a FLAC
> stream. They are not as widely supported by
> software applications, but there isn't much the
> Xiph community can do about that.
>
> Regards,
> Martin
> --
> Martin J Leese
> E-mail: martin.leese stanfordalumni.org
> Web: http://members.tripod.com/martin_leese/
>
