add minrate/maxrate

MediaBrowser.Api/Playback/Hls/VideoHlsService.cs

@@ -193,7 +193,7 @@ namespace MediaBrowser.Api.Playback.Hls
 
             if (bitrate.HasValue)
             {
-                args += string.Format(" -b:v {0}", bitrate.Value.ToString(UsCulture));
+                args += string.Format(" -b:v {0} -maxrate {0} -minrate {0} -bufsize ({0}/3)*2", bitrate.Value.ToString(UsCulture));
             }
             
             // Add resolution params, if specified