Use attachment filename if available.

MediaBrowser.Api/Attachments/AttachmentService.cs

@@ -20,7 +20,7 @@ using MimeTypes = MediaBrowser.Model.Net.MimeTypes;
 
 namespace MediaBrowser.Api.Attachments
 {
-    [Route("/Videos/{Id}/{MediaSourceId}/Attachments/{Index}/Attachment", "GET", Summary = "Gets specified attachment.")]
+    [Route("/Videos/{Id}/{MediaSourceId}/Attachments/{Index}/{Filename}", "GET", Summary = "Gets specified attachment.")]
     public class GetAttachment
     {
         [ApiMember(Name = "Id", Description = "Item Id", IsRequired = true, DataType = "string", ParameterType = "path", Verb = "GET")]
@@ -31,6 +31,9 @@ namespace MediaBrowser.Api.Attachments
 
         [ApiMember(Name = "Index", Description = "The attachment stream index", IsRequired = true, DataType = "int", ParameterType = "path", Verb = "GET")]
         public int Index { get; set; }
+
+        [ApiMember(Name = "Filename", Description = "The attachment filename", IsRequired = false, DataType = "string", ParameterType = "path", Verb = "GET")]
+        public string Filename { get; set; }
     }
 
     public class AttachmentService : BaseApiService

MediaBrowser.Api/Playback/MediaInfoService.cs

@@ -527,10 +527,12 @@ namespace MediaBrowser.Api.Playback
 
             foreach (var attachment in mediaSource.MediaAttachments)
             {
-                attachment.DeliveryUrl = string.Format("/Videos/{0}/{1}/Attachments/{2}/Attachment",
+                var filename = string.IsNullOrWhiteSpace(attachment.Filename) ? "Attachment" : attachment.Filename;
+                attachment.DeliveryUrl = string.Format("/Videos/{0}/{1}/Attachments/{2}/{3}",
                     item.Id,
                     mediaSource.Id,
-                    attachment.Index);
+                    attachment.Index,
+                    filename);
             }
         }