Expression Encoder 4 in a WCF service

Question

I am trying to write a WCF service that would run in IIS 8 and would use the Expression Encoder SDK to open a video file and then encode it as a WMV. The following code works fine when it's in a desktop application I wrote earlier.

Job job = new Job();
job.ApplyPreset(Preset.FromFile(HttpRuntime.AppDomainAppPath + "Profiles\\" + profile + ".xml"));
job.CreateSubfolder = false;
job.SaveJobFileToOutputDirectory = false;
job.OutputDirectory = Path.GetDirectoryName(input);
MediaItem item;
item = new MediaItem(input);
item.OutputFileName = "{Original file name}.wmv";
job.MediaItems.Add(item);

job.EncodeProgress += new EventHandler<EncodeProgressEventArgs>(job_EncodeProgress);
job.EncodeCompleted += new EventHandler<EncodeCompletedEventArgs>(job_EncodeCompleted);
job.Encode();

But when I try to run this code in a WCF service running on IIS I get the following error

The type initializer for 'Microsoft.Expression.Encoder.SkuManager' threw an exception.
at Microsoft.Expression.Encoder.SkuManager.IsFeaturedSupported(Feature feature)
at MS.Internal.Expression.Encoder.FastProperties.FastPropertyCreate.ShouldAddProp(IFastProperty property, PropertyType propType)
at MS.Internal.Expression.Encoder.FastProperties.FastPropertyCreate.CreatePropertiesArray[T](Type classType, PropertyType propType)
at MS.Internal.Expression.Encoder.FastProperties.FastPropertyCreate.GetProperties[T](PropertyType propType)
at MS.Internal.Expression.Encoder.Persistence.JobPersistence.GetJobFilePropertiesCore[T](JobPropertiesMode mode)
at MS.Internal.Expression.Encoder.Persistence.JobPersistence.GetJobFileProperties[T](JobPropertiesMode mode)
at Microsoft.Expression.Encoder.JobBase.CreateDefaultValues(JobBase job)
at Microsoft.Expression.Encoder.JobBase..ctor()
at Microsoft.Expression.Encoder.Job..ctor()

I can run this code in a regular desktop application on the server, but not in a WCF service running on the same machine.

Answer 1

It turns out it was a permissions problem in IIS.

In order for any program to use the Expression Encoder SDK it needs to be running under an identity that can access the Expression Encoder program installed on the machine.

So in IIS the "ApplicationPoolIdentity" identity that the WCF service was running on didn't have permissions to launch the Expression Encoder program that was installed on the machine by the "Administrator" account.

To fix this you can do one of two things.

1. When you are installing Expression Encoder allow "All Users" to be able to launch it.

2. When you install your WCF service on IIS make sure it's running in an application pool that can launch Expression Encoder

Answer 2

I had this same issue in an iis8 web site (not hosting any wcf service tho) and yes i also discovered that IIS needs to run under permissions that can execute expression encoder. BUT one day it just stopped working and started throwing the same error:

"The type initializer for 'Microsoft.Expression.Encoder.SkuManager' threw an exception."

Even though the AppPool's identity was a good one. I pulled my hair out for a day or so then realized that somehow the binaries that VS copies to the local bin directory didn't want to be run in IIS. Somehow corrupted or dll mismatch with expression's installation???. I had to delete the contents of the bin directory and, then VS replaced them, and it worked. Setting CopyLocal to false for those references did not work (conceivably it might be nice to just use from the gac).