Fix exceptions while scanning

Fixes these exceptions:
```
[2019-12-22 20:48:14.779 +01:00] [ERR] Error in WaitForExit
System.InvalidOperationException: No process is associated with this object.
   at System.Diagnostics.Process.EnsureState(State state)
   at System.Diagnostics.Process.EnsureState(State state)
   at System.Diagnostics.Process.GetWaitState()
   at System.Diagnostics.Process.WaitForExitCore(Int32 milliseconds)
   at System.Diagnostics.Process.WaitForExit(Int32 milliseconds)
   at Emby.Server.Implementations.Diagnostics.CommonProcess.WaitForExit(Int32 timeMs) in /home/pi/dev/jellyfin/Emby.Server.Implementations/Diagnostics/CommonProcess.cs:line 100
   at MediaBrowser.MediaEncoding.Encoder.MediaEncoder.StopProcess(ProcessWrapper process, Int32 waitTimeMs) in /home/pi/dev/jellyfin/MediaBrowser.MediaEncoding/Encoder/MediaEncoder.cs:line 785
[2019-12-22 20:48:14.790 +01:00] [INF] Killing ffmpeg process
[2019-12-22 20:48:14.795 +01:00] [ERR] Error killing process
System.InvalidOperationException: No process is associated with this object.
   at System.Diagnostics.Process.EnsureState(State state)
   at System.Diagnostics.Process.EnsureState(State state)
   at System.Diagnostics.Process.Kill()
   at Emby.Server.Implementations.Diagnostics.CommonProcess.Kill() in /home/pi/dev/jellyfin/Emby.Server.Implementations/Diagnostics/CommonProcess.cs:line 95
   at MediaBrowser.MediaEncoding.Encoder.MediaEncoder.StopProcess(ProcessWrapper process, Int32 waitTimeMs) in /home/pi/dev/jellyfin/MediaBrowser.MediaEncoding/Encoder/MediaEncoder.cs:line 799
[2019-12-22 20:48:14.808 +01:00] [ERR] Error in "ffprobe"
System.Text.Json.JsonException: The JSON value could not be converted to System.String. Path: $.streams[0].start_pts | LineNumber: 32 | BytePositionInLine: 26.
 ---> System.InvalidOperationException: Cannot get the value of a token type 'Number' as a string.
   at System.Text.Json.Utf8JsonReader.GetString()
   at System.Text.Json.Serialization.Converters.JsonConverterString.Read(Utf8JsonReader& reader, Type typeToConvert, JsonSerializerOptions options)
   at System.Text.Json.JsonPropertyInfoNotNullable`4.OnRead(JsonTokenType tokenType, ReadStack& state, Utf8JsonReader& reader)
   at System.Text.Json.JsonPropertyInfo.Read(JsonTokenType tokenType, ReadStack& state, Utf8JsonReader& reader)
   at System.Text.Json.JsonSerializer.HandleValue(JsonTokenType tokenType, JsonSerializerOptions options, Utf8JsonReader& reader, ReadStack& state)
   at System.Text.Json.JsonSerializer.ReadCore(JsonSerializerOptions options, Utf8JsonReader& reader, ReadStack& readStack)
   --- End of inner exception stack trace ---
   at System.Text.Json.ThrowHelper.ReThrowWithPath(ReadStack& readStack, Utf8JsonReader& reader, Exception ex)
   at System.Text.Json.JsonSerializer.ReadCore(JsonSerializerOptions options, Utf8JsonReader& reader, ReadStack& readStack)
   at System.Text.Json.JsonSerializer.ReadCore(JsonReaderState& readerState, Boolean isFinalBlock, ReadOnlySpan`1 buffer, JsonSerializerOptions options, ReadStack& readStack)
   at System.Text.Json.JsonSerializer.ReadAsync[TValue](Stream utf8Json, Type returnType, JsonSerializerOptions options, CancellationToken cancellationToken)
   at MediaBrowser.MediaEncoding.Encoder.MediaEncoder.GetMediaInfoInternal(String inputPath, String primaryPath, MediaProtocol protocol, Boolean extractChapters, String probeSizeArgument, Boolean isAudio, Nullable`1 videoType, Boolean forceEnableLogging, CancellationToken cancellationToken) in /home/pi/dev/jellyfin/MediaBrowser.MediaEncoding/Encoder/MediaEncoder.cs:line 399
   at MediaBrowser.Providers.MediaInfo.FFProbeVideoInfo.ProbeVideo[T](T item, MetadataRefreshOptions options, CancellationToken cancellationToken) in /home/pi/dev/jellyfin/MediaBrowser.Providers/MediaInfo/FFProbeVideoInfo.cs:line 122
   at MediaBrowser.Providers.Manager.MetadataService`2.RunCustomProvider(ICustomMetadataProvider`1 provider, TItemType item, String logName, MetadataRefreshOptions options, RefreshResult refreshResult, CancellationToken cancellationToken) in /home/pi/dev/jellyfin/MediaBrowser.Providers/Manager/MetadataService.cs:line 815
```

1 files changed, 8 insertions, 13 deletions

diff --git a/MediaBrowser.MediaEncoding/Probing/FFProbeHelpers.cs b/MediaBrowser.MediaEncoding/Probing/FFProbeHelpers.cs
index e4eabaf38..cd3d82e86 100644
--- a/MediaBrowser.MediaEncoding/Probing/FFProbeHelpers.cs
+++ b/MediaBrowser.MediaEncoding/Probing/FFProbeHelpers.cs
@@ -16,24 +16,19 @@ namespace MediaBrowser.MediaEncoding.Probing
                 throw new ArgumentNullException(nameof(result));
             }
 
-            if (result.format != null && result.format.tags != null)
+            if (result.Format != null && result.Format.Tags != null)
             {
-                result.format.tags = ConvertDictionaryToCaseInSensitive(result.format.tags);
+                result.Format.Tags = ConvertDictionaryToCaseInSensitive(result.Format.Tags);
             }
 
-            if (result.streams != null)
+            if (result.Streams != null)
             {
                 // Convert all dictionaries to case insensitive
-                foreach (var stream in result.streams)
+                foreach (var stream in result.Streams)
                 {
-                    if (stream.tags != null)
+                    if (stream.Tags != null)
                     {
-                        stream.tags = ConvertDictionaryToCaseInSensitive(stream.tags);
-                    }
-
-                    if (stream.disposition != null)
-                    {
-                        stream.disposition = ConvertDictionaryToCaseInSensitive(stream.disposition);
+                        stream.Tags = ConvertDictionaryToCaseInSensitive(stream.Tags);
                     }
                 }
             }
@@ -45,7 +40,7 @@ namespace MediaBrowser.MediaEncoding.Probing
         /// <param name="tags">The tags.</param>
         /// <param name="key">The key.</param>
         /// <returns>System.String.</returns>
-        public static string GetDictionaryValue(Dictionary<string, string> tags, string key)
+        public static string GetDictionaryValue(IReadOnlyDictionary<string, string> tags, string key)
         {
             if (tags == null)
             {
@@ -103,7 +98,7 @@ namespace MediaBrowser.MediaEncoding.Probing
         /// </summary>
         /// <param name="dict">The dict.</param>
         /// <returns>Dictionary{System.StringSystem.String}.</returns>
-        private static Dictionary<string, string> ConvertDictionaryToCaseInSensitive(Dictionary<string, string> dict)
+        private static Dictionary<string, string> ConvertDictionaryToCaseInSensitive(IReadOnlyDictionary<string, string> dict)
         {
             return new Dictionary<string, string>(dict, StringComparer.OrdinalIgnoreCase);
         }