How to set Transcode aspect ratio to 1.714

How can i set the transcode settings to a different aspect ratio:

  Code:

Width: 1344 pixels
Height: 784 pixels
Display aspect ratio: 1.714 or 12:7

I tried editing the profiles.xml with the DAR="12:7" and DAR="1.714" but both failed with a similar error. Is there any other way i can change the aspect ratio on transcoded files?

  Code:

<Video targetContainer="asf" targetVCodec="wmv2" targetACodec="wmav2" maxVBitrate="15360" forceVTranscoding="true" forceStereo="true" maxHeight="784" DAR="1.714">
   <Matches container="*" />
</Video>

But serviio failed to start with this error in serviio.log:

  Code:

XML Profiles.xsd didn't pass validation, reason: cvc-enumeration-valid: Value '1.714' is not facet-valid with respect to enumeration '[16:9]'. It must be a value from the enumeration.

I uploaded the full log file to Microsoft Skydrive:
http://sdrv.ms/10iDeEA