[AudioTranscoding] Add FLAC as supported target audio format and be able to define the corresponding target sample rate

Emby.Dlna/PlayTo/PlayToController.cs

@@ -945,7 +945,10 @@ namespace Emby.Dlna.PlayTo
                 request.DeviceId = values.GetValueOrDefault("DeviceId");
                 request.MediaSourceId = values.GetValueOrDefault("MediaSourceId");
                 request.LiveStreamId = values.GetValueOrDefault("LiveStreamId");
-                request.IsDirectStream = string.Equals("true", values.GetValueOrDefault("Static"), StringComparison.OrdinalIgnoreCase);
+
+                // Be careful, IsDirectStream==true by default (Static != false or not in query).
+                // See initialization of StreamingRequestDto in AudioController.GetAudioStream() method : Static = @static ?? true.
+                request.IsDirectStream = !string.Equals("false", values.GetValueOrDefault("Static"), StringComparison.OrdinalIgnoreCase);
 
                 request.AudioStreamIndex = GetIntValue(values, "AudioStreamIndex");
                 request.SubtitleStreamIndex = GetIntValue(values, "SubtitleStreamIndex");

MediaBrowser.Model/Dlna/StreamInfo.cs

@@ -185,6 +185,8 @@ namespace MediaBrowser.Model.Dlna
                     continue;
                 }
 
+                // Be careful, IsDirectStream==true by default (Static != false or not in query).
+                // See initialization of StreamingRequestDto in AudioController.GetAudioStream() method : Static = @static ?? true.
                 if (string.Equals(pair.Name, "Static", StringComparison.OrdinalIgnoreCase) &&
                     string.Equals(pair.Value, "true", StringComparison.OrdinalIgnoreCase))
                 {