fixes #528 - Support podcasts in web client

MediaBrowser.Api/Playback/BaseStreamingService.cs

@@ -470,12 +470,15 @@ namespace MediaBrowser.Api.Playback
         /// <returns>System.Nullable{System.Int32}.</returns>
         protected int? GetNumAudioChannelsParam(StreamRequest request, MediaStream audioStream)
         {
-            if (audioStream.Channels > 2 && request.AudioCodec.HasValue)
+            if (audioStream != null)
             {
-                if (request.AudioCodec.Value == AudioCodecs.Wma)
+                if (audioStream.Channels > 2 && request.AudioCodec.HasValue)
                 {
-                    // wmav2 currently only supports two channel output
-                    return 2;
+                    if (request.AudioCodec.Value == AudioCodecs.Wma)
+                    {
+                        // wmav2 currently only supports two channel output
+                        return 2;
+                    }
                 }
             }
 

MediaBrowser.Api/Playback/Progressive/AudioService.cs

@@ -6,9 +6,7 @@ using MediaBrowser.Controller.Library;
 using MediaBrowser.Controller.Persistence;
 using MediaBrowser.Model.IO;
 using ServiceStack.ServiceHost;
-using System;
 using System.Collections.Generic;
-using System.IO;
 
 namespace MediaBrowser.Api.Playback.Progressive
 {
@@ -94,7 +92,7 @@ namespace MediaBrowser.Api.Playback.Progressive
             {
                 audioTranscodeParams.Add("-ac " + channels.Value);
             }
-
+            
             if (request.AudioSampleRate.HasValue)
             {
                 audioTranscodeParams.Add("-ar " + request.AudioSampleRate.Value);