diff --git a/src/JT1078.Flv/Audio/FaacEncoder.cs b/src/JT1078.Flv/Audio/FaacEncoder.cs
index 6372a60..f0423d6 100644
--- a/src/JT1078.Flv/Audio/FaacEncoder.cs
+++ b/src/JT1078.Flv/Audio/FaacEncoder.cs
@@ -55,6 +55,7 @@ namespace JT1078.Flv.Audio
 
         public void Dispose()
         {
+            frameCache = null;
             if (faacEncHandle != IntPtr.Zero)
             {
                 FaacEncClose(faacEncHandle);
diff --git a/src/JT1078.Flv/FlvEncoder.cs b/src/JT1078.Flv/FlvEncoder.cs
index 3ffc202..20c9a37 100644
--- a/src/JT1078.Flv/FlvEncoder.cs
+++ b/src/JT1078.Flv/FlvEncoder.cs
@@ -231,11 +231,8 @@ namespace JT1078.Flv
                 nalus.Remove(sei);
                 if (needVideoHeader)
                 {
-                    if (needVideoHeader)
-                    {
-                        var firstVideoTag = EncoderFirstVideoTag(sps, pps, sei);
-                        flvMessagePackWriter.WriteArray(firstVideoTag);
-                    }
+                    var firstVideoTag = EncoderFirstVideoTag(sps, pps, sei);
+                    flvMessagePackWriter.WriteArray(firstVideoTag);
                 }
                 foreach (var naln in nalus)
                 {