Re: Writing a glib/vfs id3 library/MP3s to test.

[Bastien Nocera <hadess hadess net>]

On Wed, 2003-08-20 at 00:14, Brian Kerrick Nickel wrote:
> > Interesting.  Have you considered collaborating with Thomas Vander
> > Stichele on his media-info library?
> I probably will when I've cleaned everything up a bit.
> 
> > As for using this in rb - well it would definitely be an improvement
> > over the currently very gross libid3tag.
> Maybe, or maybe not, using my core functions isn't that fun:
>  gchar **strings = NULL;
>  gid3frame *frame = g_id3_get_T___( tag, "TIT2", &strings, NULL );
>  if( frame != NULL && strings[ 0 ] != NULL )
> 	 title = g_strdup( strings[ 0 ] );
>  else
> 	 title = g_strdup( "Untitled" );
>  if( strings )
> 	 g_strfreev( strings );
>  
> Of course the most common things will be wrapped with simple functions.
> 
> > But I think it would be cleaner to have something GStreamer-based.
> Not to worry, the library itself isn't a vfs library. It is a large
> collection of functions/structs for reading from any string, be it a
> stream, a file, or anything else:
>  gid3tag *tag = g_id3_tag_new( );
> 
>  // Some stream stuff.
> 
>  // buffer = 10 bytes from stream
>  if( g_id3_tag_read_header( tag, buffer ) != FALSE )
>  {
> 	 // Stream read tag->size bytes from the stream directly after
> 	 // current buffer.
> 
> 	 g_id3_tag_read( tag, new_buffer );
> 
> 	 // Do stuff with the tag.
> 	 some_function( tag );
>  }
> 
>  // Some more stuff.
> 
>  g_id3_tag_free( tag );

That looks quite awful. Take a look at the code used in libvorbis and
rhythmbox' monkey-media to get the comments:
- you virtualise open(), close(), read() and write()
- you make the code in libid3tag make use of user-supplied callbacks or
the posix fallbacks
- you write the gnome-vfs callbacks in monkey-media
- you get the changes to libid3tag accepted upstream.

Look at vorbis-stream-info-impl.c for ideas.

It's nice and clean, and you don't need to reimplement everything from
scratch.

Cheers

-- 
Bastien Nocera <hadess hadess net>