Message from discussion
Metadata from OGG, FLAC and zero duration
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From: Cristian Adam <cristian.a...@gmail.com>
Newsgroups: microsoft.public.windowsmedia.player
Subject: Re: Metadata from OGG, FLAC and zero duration
Date: Sun, 22 Feb 2009 06:16:45 -0800 (PST)
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Hi Zach,
Thanks for reading this post, from you answer I understand that I
should talk with the author
of WMP Tag Support Extender, because this is the safest way to manage
metadata for
a 3rd party.
Luckily WMP Tag Support Extender is an opensource project and I can
find out how he
implemented that.
I have created a small test program which uses de Windows Media SDK to
add metadata
for a media file. I have managed to add all the important metadata
(Artist, Album, Title, Genre, Year),
except album picture.
Album picture is related to every media data by it's "TrackID", this
TrackID is generated by Windows
Media Player, and you cannot change it programatically. The picture
for this TrackID resides in
c:\Documents and Settings\<USER NAME>\Local Settings\Application Data
\Microsoft\Media Player\Art Cache\LocalMLS\
If you decide to click on "Find Album Info" Windows Media Player will
generate other
metadata values for "WM/WMCollectionGroupID" and "WM/WMCollectionID",
and two files
in the directory where your media file resides, AlbumArt_{GUID}
_Large.jpg and AlbumArt_{GUID}_Small.jpg
The upper two metadata fields are readonly, you cannot change them
programatically.
The only way to display the album art is by getting the TrackID of the
media file and then
generate the jpg file in the LocalMLS folder, a bit hackish but it
will work.
The problem with seeking is due to the fact that the following
metadata fields are
not set: "Duration" and "Bitrate", so the fact that Windows Media
Player
doesn't rely on metadata do determine the length of a song it's a LIE.
These two fields
are readonly!
So I don't know what to do in order to enable seeking! Microsoft has
ensured that only
MP3 and WMA will have the seek capability in Windows Media Player.
It's so easy
to blame the 3rd party developers for "mal praxis" when you know that
they will never get it right!
Unfortunately I cannot prove this by manually modifying the database
(CurrentDatabase_360.wmdb)
in order to change Duration and Bitrate fields.
A DirectShow source filter can add its metadata to Windows Media
Player only if it uses
IWMPMedia::setItemInfo, in order to get a IWMPMedia object it has to
create a WindowsMediaPlayer
object and then query for an IWMPMediaCollection object and then
calling add function can
give access to an IWMPMedia object.
The problem with the above scenario is that it takes time to create an
media player object and add
metatadata. On my system it was on average 1.3 seconds to add metadata
for a media file.
Therefore a DirectShow filter should add its metadata on a separate
thread, or risk having a few seconds
of silence before the start of the song.
In summary it would have been nice if Microsoft would:
1. provide a mechanism for querying metadata when files were added to
the library.
2. provide a mechanism to load / save metadata from a DirectShow
filter
3. give access for 3rd parties to Advanced Tag Editor
IPersistMediaPropertyBag would have been the right interface to load /
store metadata.
All of that can be achieved if Microsoft would provide an A to Z
sample of how to add a new type
of media file to Windows Media Player, a variation of a WAV format, or
something really simple.
I wonder what changed from this point of view in Windows Media Player
12, Windows 7 would
have a chance of fixing all these problems!
Cheers!
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