Review usage of string.Substring (part 1)

Reduced allocations by replacing string.Substring with ReadOnlySpan<char>.Slice

Emby.Dlna/Didl/DidlBuilder.cs

@@ -364,7 +364,8 @@ namespace Emby.Dlna.Didl
                 writer.WriteAttributeString("bitrate", totalBitrate.Value.ToString(_usCulture));
             }
 
-            var mediaProfile = _profile.GetVideoMediaProfile(streamInfo.Container,
+            var mediaProfile = _profile.GetVideoMediaProfile(
+                streamInfo.Container,
                 streamInfo.TargetAudioCodec.FirstOrDefault(),
                 streamInfo.TargetVideoCodec.FirstOrDefault(),
                 streamInfo.TargetAudioBitrate,

Emby.Dlna/DlnaManager.cs

@@ -387,7 +387,7 @@ namespace Emby.Dlna
 
             foreach (var name in _assembly.GetManifestResourceNames())
             {
-                if (!name.StartsWith(namespaceName))
+                if (!name.StartsWith(namespaceName, StringComparison.Ordinal))
                 {
                     continue;
                 }
@@ -406,7 +406,7 @@ namespace Emby.Dlna
 
                         using (var fileStream = new FileStream(path, FileMode.Create, FileAccess.Write, FileShare.Read))
                         {
-                            await stream.CopyToAsync(fileStream);
+                            await stream.CopyToAsync(fileStream).ConfigureAwait(false);
                         }
                     }
                 }
@@ -509,7 +509,7 @@ namespace Emby.Dlna
             return _jsonSerializer.DeserializeFromString<DeviceProfile>(json);
         }
 
-        class InternalProfileInfo
+        private class InternalProfileInfo
         {
             internal DeviceProfileInfo Info { get; set; }