video : improve runtime video filter activation

There was two issues with the former module matching routing :

1. the routine searched for only one module name match
it would fail given multiple modules had the same module name and score
as an example, if a video filter have the same module name and score as an opengl filter, the opengl filter would be ordered first and the capability match would fail
2. the routine only searched for module names
given module names are defined at build time, multiple submodules in the same source file with the same capability and score would have matched the search

To prevent this, the search walk through all modules trying to match with each module shortcuts until the capability is satisfied

include/vlc_modules.h

@@ -200,6 +200,16 @@ VLC_API bool module_provides(const module_t *m, const char *cap);
  */
 VLC_API const char * module_get_object(const module_t *m) VLC_USED;
 
+
+/**
+ * Gets the shortcut names of a module.
+ *
+ * \param m the module
+ * \param n [OUT] pointer to the number of shortcuts
+ * \return the module name
+ */
+VLC_API const char **module_get_shortcuts(const module_t *m, size_t *n) VLC_USED;
+
 /**
  * Gets the human-friendly name of a module.
  *

lib/video.c

@@ -611,28 +611,50 @@ static int get_filter_str( vlc_object_t *p_parent, const char *psz_name,
 {
     char *psz_parser;
     char *psz_string;
-    const char *psz_filter_type;
+    const char *psz_filter_type = NULL;
 
-    module_t *p_obj = module_find( psz_name );
-    if( !p_obj )
+    size_t sz_modules, sz_shortcuts;
+    module_t **list = module_list_get (&sz_modules);
+    module_t *p_obj = NULL;
+    for (size_t i = 0; i < sz_modules; i++)
     {
-        msg_Err( p_parent, "Unable to find filter module \"%s\".", psz_name );
-        return VLC_EGENERIC;
-    }
+        module_t *module = list[i];
+        const char **shortcuts_list = module_get_shortcuts(module, &sz_shortcuts);
+        if ( shortcuts_list == NULL )
+            continue;
+        
+        for (size_t i = 0; i < sz_shortcuts; i++) 
+        {
+            const char *shortcut = shortcuts_list[i];
+            if ( !strcmp( shortcut, psz_name ) )
+            {
+                if( module_provides( module, "video filter" ) )
+                {
+                    psz_filter_type = "video-filter";
+                }
+                else if( module_provides( module, "sub source" ) )
+                {
+                    psz_filter_type = "sub-source";
+                }
+                else if( module_provides( module, "sub filter" ) )
+                {
+                    psz_filter_type = "sub-filter";
+                }
+            }
 
-    if( module_provides( p_obj, "video filter" ) )
-    {
-        psz_filter_type = "video-filter";
-    }
-    else if( module_provides( p_obj, "sub source" ) )
-    {
-        psz_filter_type = "sub-source";
-    }
-    else if( module_provides( p_obj, "sub filter" ) )
-    {
-        psz_filter_type = "sub-filter";
+            if ( psz_filter_type )
+                break;
+        }
+
+        if ( psz_filter_type ) {
+            p_obj = module;
+            break;
+        }
     }
-    else
+
+    module_list_free (list);
+    
+    if ( p_obj == NULL )
     {
         msg_Err( p_parent, "Unknown video filter type." );
         return VLC_EGENERIC;

src/libvlccore.sym

@@ -264,6 +264,7 @@ module_config_get
 module_find
 module_get_capability
 module_get_help
+module_get_shortcuts
 module_get_name
 module_get_object
 module_get_score

src/modules/modules.c

@@ -54,6 +54,18 @@ const char *module_get_object( const module_t *m )
     return m->pp_shortcuts[0];
 }
 
+const char **module_get_shortcuts(const module_t *m, size_t *n)
+{
+    assert (m != NULL);
+    assert (n != NULL);
+    *n = m->i_shortcuts;
+
+    if (unlikely(m->i_shortcuts == 0))
+        return NULL;
+
+    return m->pp_shortcuts;
+}
+
 const char *module_get_name( const module_t *m, bool long_name )
 {
     if( long_name && ( m->psz_longname != NULL) )