Change Citrix HDX Encoder on the fly for testing

Change Citrix HDX Encoder on the fly for testing

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Rachel Berry posted an article on optimizing HDX for gaming.  In this article she highlighted that Citrix has some ‘special’ registry keys for modifying different parameters of the Thinwire encoder.  One of these keys was changing the encoder itself:

  • Encoder = 2 is Pure H.264 (YUV 4:2:0). As with most vendors this is H.264 4:2:0 format, it’s designed for a balance of quality and bandwidth primarily on video and high-bandwidth CAD parts (not much text). This is used by the HDX 3D Pro VDA.
  • Encoder = 1 is H.264+lossless text. This is used by default by the XenDesktop standard VDA and XenApp VDA.
  • Encoder = 0 forces you to use Compatibility mode

In terms used by HDX, it shakes out like so:

Encoder 2 = DeepCompressionEncoder
Encoder 1 = DeepCompressionV2Encoder
Encoder 0 = CompatibilityEncoder

The cool thing about these encoders is you can modify their values *on the fly* and it will take place immediately in your Citrix session. This video I made demonstrates this. I ran a 3D benchmark application and modified the encoder’s on the fly. I zoomed into the FPS counter and put this in the bottom left corner as the text with moving images shows much better the difference in the encoders.  Without a doubt, the CompatibilityEncoder has the worst quality of all the encoders when it comes to video/moving images/3D/gaming.

Try to watch it in 1080p for maximum quality.

To change the encoder, you need to add/modify a registry key at HKLM\Software\Citrix\Graphics.  The type is DWORD32 named “Encoder” and the value is 0x0 to 0x2, depending on the encoder you want to try and use.
All testing was done with XenApp 7.6 on my home built lab.

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