use api duration value as placeholder

src/playbin.vala

@@ -243,7 +243,7 @@ class Playbin : GLib.Object {
 
         this.current_song = song;
         this.position = 0;
-        this.duration = 1;
+        this.duration = song.duration * 1000000000 - 1;
         this.now_playing (false);
     }
 

src/subsonic.vala

@@ -61,6 +61,7 @@ public class Subsonic.Song : Object {
     public int64 track { get; private set; }
     public int64 year { get; private set; }
     public DateTime? starred { get; private set; }
+    public int64 duration { get; private set; }
 
     public Song (Json.Reader reader) {
         reader.read_member ("id");
@@ -86,6 +87,10 @@ public class Subsonic.Song : Object {
         reader.read_member ("year");
         this.year = reader.get_int_value ();
         reader.end_member ();
+
+        reader.read_member ("duration");
+        this.duration = reader.get_int_value ();
+        reader.end_member ();
     }
 }
 

src/ui/window.vala

@@ -135,6 +135,10 @@ class Ui.Window : Adw.ApplicationWindow {
     }
 
     [GtkCallback] private string format_timestamp (int64 ns) {
+        if (ns == 1) {
+            // treat 1 nanosecond as a sentinel value
+            return "-";
+        }
         int64 ms = ns / 1000000;
         int s = (int) (ms / 1000);
         return "%02d:%02d".printf (s/60, s%60);