Some more (mostly) untested stuff:

 * Secondary queue items now have a b_fetch_art flag
 * You can use the playlist_AskForArtEnqueue function to ask for art from an interface. This will enqueue at the begining of the secondary queue
 * other stuff which i don't remember :)
 * (fix issues with previous (and unrelated) DIR_SEP commit)

include/vlc_common.h

@@ -237,6 +237,7 @@ typedef struct services_discovery_t services_discovery_t;
 typedef struct services_discovery_sys_t services_discovery_sys_t;
 typedef struct playlist_add_t playlist_add_t;
 typedef struct playlist_preparse_t playlist_preparse_t;
+typedef struct playlist_secondary_preparse_t playlist_secondary_preparse_t;
 
 /* Modules */
 typedef struct module_bank_t module_bank_t;
@@ -1280,7 +1281,9 @@ VLC_EXPORT( const char *, VLC_Changeset, ( void ) );
 #endif
 
 #if defined( WIN32 ) || defined( UNDER_CE )
+#   define DIR_SEP_CHAR '\\'
 #   define DIR_SEP "\\"
 #else
+#   define DIR_SEP_CHAR '/'
 #   define DIR_SEP "/"
 #endif

include/vlc_input.h

@@ -476,6 +476,8 @@ VLC_EXPORT( void,             input_DestroyThread,  ( input_thread_t * ) );
 
 #define input_MetaFetch(a,b) __input_MetaFetch(VLC_OBJECT(a),b)
 VLC_EXPORT( int, __input_MetaFetch, ( vlc_object_t *, input_item_t * ) );
+#define input_ArtFetch(a,b) __input_ArtFetch(VLC_OBJECT(a),b)
+VLC_EXPORT( int, __input_ArtFetch, ( vlc_object_t *, input_item_t * ) );
 
 enum input_query_e
 {

include/vlc_playlist.h

@@ -145,7 +145,7 @@ struct playlist_t
     mtime_t               i_vout_destroyed_date;
     mtime_t               i_sout_destroyed_date;
     playlist_preparse_t  *p_preparse; /**< Preparser object */
-    playlist_preparse_t  *p_secondary_preparse; /**< Preparser object */
+    playlist_secondary_preparse_t *p_secondary_preparse;/**< Preparser object */
 
     vlc_mutex_t gc_lock;         /**< Lock to protect the garbage collection */
 
@@ -237,6 +237,7 @@ VLC_EXPORT( void,  playlist_LockClear, ( playlist_t * ) );
 
 VLC_EXPORT( int, playlist_PreparseEnqueue, (playlist_t *, input_item_t *) );
 VLC_EXPORT( int, playlist_PreparseEnqueueItem, (playlist_t *, playlist_item_t *) );
+VLC_EXPORT( int, playlist_AskForArtEnqueue, (playlist_t *, input_item_t *) );
 
 /* Services discovery */
 

include/vlc_symbols.h

@@ -546,6 +546,9 @@ struct module_symbols_t
     int (*__input_MetaFetch_inner) (vlc_object_t *, input_item_t *);
     int (*input_DownloadAndCacheArt_inner) (vlc_object_t *p_parent, input_item_t *p_item);
     uint32_t (*input_GetMetaEngineFlags_inner) (vlc_meta_t *p_meta);
+    int (*__input_ArtFetch_inner) (vlc_object_t *, input_item_t *);
+    void *input_AskForArt_deprecated;
+    int (*playlist_AskForArtEnqueue_inner) (playlist_t *, input_item_t *);
 };
 # if defined (__PLUGIN__)
 #  define aout_FiltersCreatePipeline (p_symbols)->aout_FiltersCreatePipeline_inner
@@ -1022,6 +1025,8 @@ struct module_symbols_t
 #  define __input_MetaFetch (p_symbols)->__input_MetaFetch_inner
 #  define input_DownloadAndCacheArt (p_symbols)->input_DownloadAndCacheArt_inner
 #  define input_GetMetaEngineFlags (p_symbols)->input_GetMetaEngineFlags_inner
+#  define __input_ArtFetch (p_symbols)->__input_ArtFetch_inner
+#  define playlist_AskForArtEnqueue (p_symbols)->playlist_AskForArtEnqueue_inner
 # elif defined (HAVE_DYNAMIC_PLUGINS) && !defined (__BUILTIN__)
 /******************************************************************
  * STORE_SYMBOLS: store VLC APIs into p_symbols for plugin access.
@@ -1501,6 +1506,8 @@ struct module_symbols_t
     ((p_symbols)->__input_MetaFetch_inner) = __input_MetaFetch; \
     ((p_symbols)->input_DownloadAndCacheArt_inner) = input_DownloadAndCacheArt; \
     ((p_symbols)->input_GetMetaEngineFlags_inner) = input_GetMetaEngineFlags; \
+    ((p_symbols)->__input_ArtFetch_inner) = __input_ArtFetch; \
+    ((p_symbols)->playlist_AskForArtEnqueue_inner) = playlist_AskForArtEnqueue; \
     (p_symbols)->net_ConvertIPv4_deprecated = NULL; \
     (p_symbols)->vlc_input_item_GetInfo_deprecated = NULL; \
     (p_symbols)->vlc_input_item_AddInfo_deprecated = NULL; \
@@ -1554,6 +1561,7 @@ struct module_symbols_t
     (p_symbols)->__intf_IntfProgress_deprecated = NULL; \
     (p_symbols)->streaming_ChainToPsz_deprecated = NULL; \
     (p_symbols)->__input_SecondaryPreparse_deprecated = NULL; \
+    (p_symbols)->input_AskForArt_deprecated = NULL; \
 
 # endif /* __PLUGIN__ */
 #endif /* __VLC_SYMBOLS_H */

src/input/meta.c

@@ -32,7 +32,7 @@
 #   include <sys/stat.h>
 #endif
 
-int input_FindArt( vlc_object_t *p_parent, input_item_t *p_item );
+int input_FindArtInCache( vlc_object_t *p_parent, input_item_t *p_item );
 
 int __input_MetaFetch( vlc_object_t *p_parent, input_item_t *p_item )
 {
@@ -55,7 +55,7 @@ int __input_MetaFetch( vlc_object_t *p_parent, input_item_t *p_item )
         i_optional |= VLC_META_ENGINE_ART_URL;
     }
 
-    input_FindArt( p_parent, p_item );
+    input_FindArtInCache( p_parent, p_item );
 
     i_meta = input_GetMetaEngineFlags( p_item->p_meta );
     i_mandatory &= ~i_meta;
@@ -87,18 +87,34 @@ int __input_MetaFetch( vlc_object_t *p_parent, input_item_t *p_item )
     return VLC_SUCCESS;
 }
 
+int __input_ArtFetch( vlc_object_t *p_parent, input_item_t *p_item )
+{
+    if( !p_item->p_meta )
+        return VLC_EGENERIC;
+
+    /* TODO: call art fetcher modules */
+
+    if( !p_item->p_meta->psz_arturl || !*p_item->p_meta->psz_arturl )
+        return VLC_EGENERIC;
+
+    if( strncmp( "file://", p_item->p_meta->psz_arturl, 7 ) )
+    {
+        return input_DownloadAndCacheArt( p_parent, p_item );
+    }
+    return VLC_SUCCESS;
+}
+
 #ifndef MAX_PATH
 #   define MAX_PATH 250
 #endif
-int input_FindArt( vlc_object_t *p_parent, input_item_t *p_item )
+int input_FindArtInCache( vlc_object_t *p_parent, input_item_t *p_item )
 {
     char *psz_artist;
     char *psz_album;
-    char *psz_type;
     char psz_filename[MAX_PATH];
     int i;
     struct stat a;
-    const char ppsz_type[] = { ".jpg", ".png", ".gif", ".bmp", "" };
+    const char *ppsz_type[] = { ".jpg", ".png", ".gif", ".bmp", "" };
 
     if( !p_item->p_meta ) return VLC_EGENERIC;
 
@@ -111,13 +127,14 @@ int input_FindArt( vlc_object_t *p_parent, input_item_t *p_item )
                   "file://%s" DIR_SEP CONFIG_DIR DIR_SEP "art"
                   DIR_SEP "%s" DIR_SEP "%s" DIR_SEP "art%s",
                   p_parent->p_libvlc->psz_homedir,
-                  psz_artist, psz_album, psz_type );
+                  psz_artist, psz_album, ppsz_type[i] );
 
         /* Check if file exists */
         if( utf8_stat( psz_filename+7, &a ) == 0 )
         {
             msg_Dbg( p_parent, "album art %s already exists in cache"
                              , psz_filename );
+            vlc_meta_SetArtURL( p_item->p_meta, psz_filename );
             return VLC_SUCCESS;
         }
     }

src/input/subtitles.c

@@ -222,7 +222,7 @@ static char **paths_to_list( char *psz_dir, char *psz_path )
                              psz_subdir[0] == '.' ? psz_dir : "",
                              psz_subdir,
                              psz_subdir[strlen(psz_subdir) - 1] ==
-                              DIR_SEP ? '\0' : DIR_SEP );
+                              DIR_SEP_CHAR ? '\0' : DIR_SEP_CHAR );
                     subdirs[i] = psz_temp;
                     i++;
                 }
@@ -277,7 +277,7 @@ char **subtitles_Detect( input_thread_t *p_this, char *psz_path,
     }
 
     /* extract filename & dirname from psz_fname */
-    tmp = strrchr( psz_fname, DIR_SEP );
+    tmp = strrchr( psz_fname, DIR_SEP_CHAR );
     if( tmp )
     {
         int dirlen = 0;
@@ -304,7 +304,7 @@ char **subtitles_Detect( input_thread_t *p_this, char *psz_path,
         }
         dirlen = strlen( f_dir );
         f_dir = (char *)realloc(f_dir, dirlen +2 );
-        f_dir[dirlen] = DIR_SEP;
+        f_dir[dirlen] = DIR_SEP_CHAR;
         f_dir[dirlen+1] = '\0';
         f_fname = FromLocaleDup( psz_fname );
     }

src/playlist/control.c

@@ -214,6 +214,27 @@ int playlist_PreparseEnqueueItem( playlist_t *p_playlist,
     return VLC_SUCCESS;
 }
 
+int playlist_AskForArtEnqueue( playlist_t *p_playlist,
+                              input_item_t *p_item )
+{
+    int i;
+    preparse_item_t p;
+    p.p_item = p_item;
+    p.b_fetch_art = VLC_TRUE;
+
+    vlc_mutex_lock( &p_playlist->p_secondary_preparse->object_lock );
+    for( i = 0; i < p_playlist->p_secondary_preparse->i_waiting &&
+         p_playlist->p_secondary_preparse->p_waiting->b_fetch_art == VLC_TRUE;
+         i++ );
+    vlc_gc_incref( p_item );
+    INSERT_ELEM( p_playlist->p_secondary_preparse->p_waiting,
+                 p_playlist->p_secondary_preparse->i_waiting,
+                 i,
+                 p );
+    vlc_mutex_unlock( &p_playlist->p_secondary_preparse->object_lock );
+    return VLC_SUCCESS;
+}
+
 void PreparseEnqueueItemSub( playlist_t *p_playlist,
                              playlist_item_t *p_item )
 {

src/playlist/engine.c

@@ -459,6 +459,7 @@ void playlist_PreparseLoop( playlist_preparse_t *p_obj )
         if( p_current )
         {
             vlc_bool_t b_preparsed = VLC_FALSE;
+            preparse_item_t p;
             if( strncmp( p_current->psz_uri, "http:", 5 ) &&
                 strncmp( p_current->psz_uri, "rtsp:", 5 ) &&
                 strncmp( p_current->psz_uri, "udp:", 4 ) &&
@@ -488,21 +489,24 @@ void playlist_PreparseLoop( playlist_preparse_t *p_obj )
              * TODO: - use i_mandatory stuff here instead of hardcoded T/A
              *       - don't do this for things we won't get meta for, like
              *         videos
+             * -> done in input_MetaFetch atm
              */
-            if( !(p_current->p_meta->psz_title && *p_current->p_meta->psz_title
+            /*if( !(p_current->p_meta->psz_title && *p_current->p_meta->psz_title
                 && p_current->p_meta->psz_artist &&
                    *p_current->p_meta->psz_artist) )
-            {
+            {*/
+                p.p_item = p_current;
+                p.b_fetch_art = VLC_FALSE;
                 vlc_mutex_lock( &p_playlist->p_secondary_preparse->object_lock);
-                INSERT_ELEM( p_playlist->p_secondary_preparse->pp_waiting,
+                INSERT_ELEM( p_playlist->p_secondary_preparse->p_waiting,
                              p_playlist->p_secondary_preparse->i_waiting,
                              p_playlist->p_secondary_preparse->i_waiting,
-                             p_current );
+                             p );
                 vlc_mutex_unlock(
                             &p_playlist->p_secondary_preparse->object_lock);
-            }
+            /*}
             else
-                vlc_gc_decref( p_current );
+                vlc_gc_decref( p_current );*/
             PL_UNLOCK;
         }
         else
@@ -519,7 +523,7 @@ void playlist_PreparseLoop( playlist_preparse_t *p_obj )
 }
 
 /** Main loop for secondary preparser queue */
-void playlist_SecondaryPreparseLoop( playlist_preparse_t *p_obj )
+void playlist_SecondaryPreparseLoop( playlist_secondary_preparse_t *p_obj )
 {
     playlist_t *p_playlist = (playlist_t *)p_obj->p_parent;
 
@@ -527,15 +531,21 @@ void playlist_SecondaryPreparseLoop( playlist_preparse_t *p_obj )
 
     if( p_obj->i_waiting > 0 )
     {
-        input_item_t *p_current = p_obj->pp_waiting[0];
-        REMOVE_ELEM( p_obj->pp_waiting, p_obj->i_waiting, 0 );
+        vlc_bool_t b_fetch_art = p_obj->p_waiting->b_fetch_art;
+        input_item_t *p_item = p_obj->p_waiting->p_item;
+        REMOVE_ELEM( p_obj->p_waiting, p_obj->i_waiting, 0 );
         vlc_mutex_unlock( &p_obj->object_lock );
-        if( p_current )
+        if( p_item )
         {
-            input_MetaFetch( p_playlist, p_current );
-            p_current->p_meta->i_status |= ITEM_META_FETCHED;
-            var_SetInteger( p_playlist, "item-change", p_current->i_id );
-            vlc_gc_decref( p_current );
+            input_MetaFetch( p_playlist, p_item );
+            p_item->p_meta->i_status |= ITEM_META_FETCHED;
+            if( b_fetch_art == VLC_TRUE )
+            {
+                input_ArtFetch( p_playlist, p_item );
+                p_item->p_meta->i_status |= ITEM_ART_FETCHED;
+            }
+            var_SetInteger( p_playlist, "item-change", p_item->i_id );
+            vlc_gc_decref( p_item );
         }
         else
             PL_UNLOCK;

src/playlist/playlist_internal.h

@@ -39,6 +39,19 @@ struct playlist_preparse_t
     input_item_t  **pp_waiting;
 };
 
+typedef struct preparse_item_t
+{
+    input_item_t *p_item;
+    vlc_bool_t   b_fetch_art;
+} preparse_item_t;
+
+struct playlist_secondary_preparse_t
+{
+    VLC_COMMON_MEMBERS
+    vlc_mutex_t     lock;
+    int             i_waiting;
+    preparse_item_t *p_waiting;
+};
 
 /*****************************************************************************
  * Prototypes
@@ -52,7 +65,7 @@ void        playlist_Destroy  ( playlist_t * );
 void playlist_MainLoop( playlist_t * );
 void playlist_LastLoop( playlist_t * );
 void playlist_PreparseLoop( playlist_preparse_t * );
-void playlist_SecondaryPreparseLoop( playlist_preparse_t * );
+void playlist_SecondaryPreparseLoop( playlist_secondary_preparse_t * );
 
 /* Control */
 playlist_item_t * playlist_NextItem  ( playlist_t * );

src/playlist/thread.c

@@ -33,7 +33,7 @@
  *****************************************************************************/
 static void RunControlThread ( playlist_t * );
 static void RunPreparse( playlist_preparse_t * );
-static void RunSecondaryPreparse( playlist_preparse_t * );
+static void RunSecondaryPreparse( playlist_secondary_preparse_t * );
 
 static playlist_t * CreatePlaylist( vlc_object_t *p_parent );
 static void HandlePlaylist( playlist_t * );
@@ -96,7 +96,7 @@ void __playlist_ThreadCreate( vlc_object_t *p_parent )
 
     // Secondary Preparse
     p_playlist->p_secondary_preparse = vlc_object_create( p_playlist,
-                                  sizeof( playlist_preparse_t ) );
+                              sizeof( playlist_secondary_preparse_t ) );
     if( !p_playlist->p_secondary_preparse )
     {
         msg_Err( p_playlist, "unable to create secondary preparser" );
@@ -104,7 +104,7 @@ void __playlist_ThreadCreate( vlc_object_t *p_parent )
         return;
     }
     p_playlist->p_secondary_preparse->i_waiting = 0;
-    p_playlist->p_secondary_preparse->pp_waiting = NULL;
+    p_playlist->p_secondary_preparse->p_waiting = NULL;
 
     vlc_object_attach( p_playlist->p_secondary_preparse, p_playlist );
     if( vlc_thread_create( p_playlist->p_secondary_preparse,
@@ -218,7 +218,7 @@ static void RunPreparse ( playlist_preparse_t *p_obj )
     }
 }
 
-static void RunSecondaryPreparse( playlist_preparse_t *p_obj )
+static void RunSecondaryPreparse( playlist_secondary_preparse_t *p_obj )
 {
     playlist_t *p_playlist = (playlist_t *)p_obj->p_parent;
     /* Tell above that we're ready */