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PCoIP Ultra Technical Series Part 7: Setting New Boundaries for Image Quality

November 6, 2019
Ian Main

Ian is Teradici's Technical Marketing Principal. Ian has over 10 years of experience at Teradici, involved in performance benchmarking, architectural aspects of PCoIP design and customer requirements analysis, with a particular focus on the media and entertainment industry. Follow Ian on Twitter! https://twitter.com/PCoIP_Ian

In this final post, I’ll touch on a subtle enhancement in our protocol which is sure to have significant impact in the future – the ability for the image encoder to operate continuously across the quality spectrum from narrowband WAN, through professional-grade user experience all the way up to every frame delivered at lossless reproduction.

Heads-up (and a very Canadian sorry!), this section gets a little technical in places…. 

PCoIP UltraTM Technical Series Part 7: Setting New Boundaries for Image Quality

PCoIP Ultra: Ready to leverage more network capacity

To date, the ability to deliver lossless video has only been achievable with technologies such as Serial Digital Interface (SDI) leveraging dedicated cabling – although there is a slow move towards IP network alternatives with lightweight compression.  I mention ‘future impact’ of PCoIP Ultra because even a modest 1080p 60 fps video workload delivered uncompressed at 24 bits-per-RGB-pixel requires several gigabits of network capacity.  The good news is that capacity is growing, and we want to be ready to leverage that with PCoIP Ultra technology – especially in broadcast and post-production where pristine image reproduction can be critical to line-of-business workflows.

 

The image quality delivered by PCoIP technology has always been a corner pin of Teradici success. It is not difficult to find independent research, such as this report on remote access protocols for DaaS solutions*, that plots PCoIP quality at a higher value for video playback than alternatives such as ICA, RDP or VNC (in this instance, even at the modest default Q80 configuration used by PCoIP technology in Amazon Workspaces).

 

Image quality beyond Q80

With PCoIP Ultra enhancements, you can choose to move the dial on image quality far beyond the default Q80 setting.  The graph below plots PSNR values at different quality settings for a reference video comprising a selection of intricate detail and easy-to-encode scenes. My testbench generates an average PSNR score from 500 sampled frames – and yes, for imaging scientists out there rolling your eyes, PSNR is a poor choice of metric but unfortunately convenient for this quick test here. I’m also a bit comforted that my structural similarity (SSIM) testbench exhibits strong correlation against PSNR for the same content.

pcoip-ultra-average-500-video-frames2


A few interesting observations:

  • The PSNR results for RDP and default PCoIP Ultra (Q80) using my reference video is a near match with the DaaS Report test referenced above which used unrelated content and sophisticated measurement techniques –providing reasonable reassurance for my testbed.
  • Once we reach Q95+, we notice diminishing returns on quality as system resources such as memory and network bandwidth saturate. PCoIP Ultra has been future-proofed in this regard.

 

As processor architectures improve and network capacity becomes available, these super-high PSNR metrics will be sustainable. That presents some exciting opportunities when considered in conjunction with emerging HDR display technologies and the needs of the media and entertainment industry!  Also, bear in mind that the build-to-lossless feature of PCoIP is retained in PCoIP Ultra so artists and designers concerned over color accuracy can be rest assured that they are working with bit-exact reproductions of the remote original content.

 

For those interested in the quality of an NVIDIA NVENC image stream in PCoIP Ultra…

The news update here is that we’ve hooked the PCoIP Image Quality Settings into the NVENC encoder which means that switching from AVX2 to NVENC at comparable quality is as simple as changing the encoder selection policy setting.  By setting NVENC at Q90 or above, you’ll be benefiting from H.264 4:4:4 chroma accuracy for bulls-eye professional grade quality. Static images settle as perceptually lossless reproductions but are not yet able to leverage build-to-lossless refinement available with PCoIP-AVX2. If your priority is bandwidth conservation, you can select a lower quality such as Q70 and take advantage of all that motion compensation goodness that H.264 brings to the table.

One last ‘under-the-hood’ side note - with PCoIP Ultra, we’ve extended both our fully lossless RGB-YUV color transform and reversible wavelet coefficients beyond 8-bit pixel values to allow for High Dynamic Range (HDR) formats in the near future. Be sure to look out for upcoming Cloud Access Software releases with some of these exciting capabilities!

 

Some helpful tools

If you’re looking for practical details such as how to get cracking with PCoIP Ultra, or how to engage the various PCoIP Ultra configurations, feel free to consult our PCoIP Session Planning Guide, a Cloud Access Software Administrator Guide or a third party guide such as the NVIDIA RTX Server Design Guide for Cloud Access Software.

 

Well that’s a wrap! I trust you found this series informative. Stay tuned as we have some awesome developments in the works under the PCoIP Ultra banner.  Hopefully I’ve provided a glimpse into this expanded foundation which paves the way for increased colour depth, even better compression, and silky-smooth video playout at fantastically high image quality levels expected by our media and entertainment customers.  I look forward to sharing more in the not too distant future!

 

If you're interested in high performance cloud workstations, check out this webinar!

In case you missed it:

Part 1: Top-Level Architecture

Part 2: PCoIP Ultra Client Capability

Part 3: Four Times the Pixel Rate

Part 4: PCoIP Ultra Efficient CPU Scaling

Part 5: What About Bandwidth Consumption?

Part 6: PCoIP Ultra Efficiency – Especially for GPU Offload

 

*Study supported by the Spanish Ministry of Economy and Competitiveness and the European Regional Development Fund, published on PLOS ONE.

 

Ian Main

Ian is Teradici's Technical Marketing Principal. Ian has over 10 years of experience at Teradici, involved in performance benchmarking, architectural aspects of PCoIP design and customer requirements analysis, with a particular focus on the media and entertainment industry. Follow Ian on Twitter! https://twitter.com/PCoIP_Ian