[neurosetta] Updating tags

[Stan Seibert]

On Fri, 2003-06-27 at 15:28, Ignacio Solis wrote:
> I guess what I'm looking for is to update the tags but not copy the
> whole file over again. I'm not an expert in mp3 or ogg so I don't know
> if the tags are at the beginning of the file or the end. I don't want to
> force the os to read the file over usb, rearrange the data (for tags of
> different sizes) and write it back.  Are the tags reserved space in an
> mp3/ogg?

Reserved space is not required.  Some programs might leave space, but I
doubt many do.  So it would require inserting data.  MP3 tags are either
at the beginning (ID3v2), the end (ID3v1/1.1) or both.  Vorbis tags are
in the second packet of the stream.

> In the case of the neuros database, is all the info gotten from there
> and only the audio from the file? In that case, could we update only the
> database?  

The Neuros gets the song information (title, artist, etc.) exclusively
from the database, and just reads the audio data from the file.  The
database values come from tags in the file at load time.

The easiest way to update the tags would be to find a program that would
first fix the files (you could do this in-place on the files on the
Neuros), and then force the database to update with "positron rebuild". 
The rebuild command will re-read all tags from the files on the Neuros
and load them into the database.  The disadvantage to this is that
updating the tags stored in files on the Neuros disk might take a long
time if there are a lot of files to change.

You could decide to update just the database, although you would have to
write your own code to do that.  You will find that because of the way
the Neuros database is structured, "updating" a record pretty much
involves deleting the old one and appending a new record at the end of
the database with the updated information.


---
Stan Seibert

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