Fix the canvas size for DVBSUB and DVDSUB subtitles

Signed-off-by: nyanmisaka <nst799610810@gmail.com>

MediaBrowser.Controller/MediaEncoding/EncodingHelper.cs

@@ -666,9 +666,12 @@ namespace MediaBrowser.Controller.MediaEncoding
 
         public string GetGraphicalSubCanvasSize(EncodingJobInfo state)
         {
+            // DVBSUB and DVDSUB use the fixed canvas size 720x576
             if (state.SubtitleStream != null
                 && state.SubtitleDeliveryMethod == SubtitleDeliveryMethod.Encode
-                && !state.SubtitleStream.IsTextSubtitleStream)
+                && !state.SubtitleStream.IsTextSubtitleStream
+                && !string.Equals(state.SubtitleStream.Codec, "DVBSUB", StringComparison.OrdinalIgnoreCase)
+                && !string.Equals(state.SubtitleStream.Codec, "DVDSUB", StringComparison.OrdinalIgnoreCase))
             {
                 var inW = state.VideoStream?.Width;
                 var inH = state.VideoStream?.Height;