Add dummy meta engine with highest priority. Will check if meta is already available.

modules/meta_engine/Modules.am

 SOURCES_musicbrainz = musicbrainz.c
+SOURCES_dummy = dummy.c

modules/meta_engine/dummy.c

+/*****************************************************************************
+ * dummy.c
+ *****************************************************************************
+ * Copyright (C) 2006 the VideoLAN team
+ * $Id$
+ *
+ * Authors: Antoine Cellerier <dionoea -at- videolan -dot- org>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston MA 02110-1301, USA.
+ *****************************************************************************/
+
+/*****************************************************************************
+ * Preamble
+ *****************************************************************************/
+#define _GNU_SOURCE
+#include <stdlib.h>                                      /* malloc(), free() */
+
+#include <vlc/vlc.h>
+#include <vlc/intf.h>
+#include <vlc_meta.h>
+#include <vlc_meta_engine.h>
+#include <charset.h>
+
+/*****************************************************************************
+ * Local prototypes
+ *****************************************************************************/
+static int FindMeta( vlc_object_t * );
+
+/*****************************************************************************
+ * Module descriptor
+ *****************************************************************************/
+
+vlc_module_begin();
+/*    set_category( CAT_INTERFACE );
+    set_subcategory( SUBCAT_INTERFACE_CONTROL );*/
+    set_shortname( N_( "Dummy" ) );
+    set_description( _("Dummy meta data") );
+
+    set_capability( "meta engine", 1000 );
+    set_callbacks( FindMeta, NULL );
+vlc_module_end();
+
+/*****************************************************************************
+ *****************************************************************************/
+static int FindMeta( vlc_object_t *p_this )
+{
+    meta_engine_t *p_me = (meta_engine_t *)p_this;
+    input_item_t *p_item = p_me->p_item;
+
+    if( !p_item->p_meta ) return VLC_EGENERIC;
+
+    uint32_t i_meta = 0;
+#define CHECK( a, b ) \
+    if( p_item->p_meta->psz_ ## a && *p_item->p_meta->psz_ ## a ) \
+        i_meta |= VLC_META_ENGINE_ ## b;
+
+    CHECK( title, TITLE )
+    CHECK( author, AUTHOR )
+    CHECK( artist, ARTIST )
+    CHECK( genre, GENRE )
+    CHECK( copyright, COPYRIGHT )
+    CHECK( album, COLLECTION )
+    CHECK( tracknum, SEQ_NUM )
+    CHECK( description, DESCRIPTION )
+    CHECK( rating, RATING )
+    CHECK( date, DATE )
+    CHECK( url, URL )
+    CHECK( language, LANGUAGE )
+    CHECK( arturl, ART_URL )
+
+    if( !(i_meta & VLC_META_ENGINE_ART_URL) )
+    {
+        if( i_meta & VLC_META_ENGINE_COLLECTION
+            && i_meta & VLC_META_ENGINE_ARTIST )
+        {
+            FILE *p_file;
+            char *psz_filename;
+            asprintf( &psz_filename,
+                      "file://%s/" CONFIG_DIR "/art/%s/%s/art.jpg", /* ahem ... we can have other filetype too... */
+                      p_me->p_libvlc->psz_homedir,
+                      p_item->p_meta->psz_artist,
+                      p_item->p_meta->psz_album );
+            p_file = utf8_fopen( psz_filename+7, "r" );
+            if( p_file )
+            {
+                fclose( p_file );
+                vlc_meta_SetArtURL( p_item->p_meta, psz_filename );
+                i_meta |= VLC_META_ENGINE_ART_URL;
+            }
+            free( psz_filename );
+        }
+    }
+
+    /* Add checks for musicbrainz meta */
+
+    if( ( p_me->i_mandatory & i_meta ) == p_me->i_mandatory )
+    {
+        return VLC_SUCCESS;
+    }
+    else
+    {
+        return VLC_EGENERIC;
+     }
+}