Netflix's HDR algorithm styled, "HDR-DO"...now available in all its 4K library

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Not new I guess…but it took Netflix at least 3 years of testing this “new HDR algorithm”…and Netflix has finally completed all her 4K content library to utilize this new HDR algorithm.

Netflix is going to make this new algorithm open-source. A collaboration between Netflix and Dolby. The new HDR algorithm will be “format agnostic” meaning it will be optimized at the signal level(source-based) instead of relying on the display (TV and Projector’s built-in Dynamic Tone-mapping or DTM in short). It looks like a game-changer for the industry. We may no longer have to contend with sub-par DTM that brings about poor shadow details in dark scenes and blown-up specular highlights in bright scenes. I can’t help but wonder if this HDR-DO algorithmn (which is “open-source”) will render products like MadVR and Lumagen irrelevant in the near future. Granted, the HDR-DO is targeted at “streaming of 4K HDR” content but the “science” behind it makes perfect sense!

For a detailed report of how Netflix team did it, you can read the tech blog here: All of Netflix’s HDR video streaming is now dynamically optimized | by Netflix Technology Blog | Nov, 2023 | Netflix TechBlog

With the 4K physical media going to “disappear” very soon and streaming slowly becoming a mainstay for home entertainment. This spells exciting times for consumers to look forward to a better 4K HDR streaming experience.

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This is super good! Totally makes sense.

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Now this is indeed exciting!

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I watched the video and then did some further research. The video actually says that the new HDR VMAF only applies to 1080p and 4K will be supported in the future. The idea is that the HDR content maps well with human perception and is optimized for bandwidth.

Some further research indicates that HDR-VMAF ignores tone mapping and does not even used the metadata provided in Dolby Vision. So HDR-VMAF does not look at peak luminance, black level, or color gamut, which are all the wonderful things that Dolby Vision and MadVR/Lumagen provide. This is quite clear in the link that Desray posted:

Netflix HDR optimization

So, no, this change to Netflix encoding may result in better video for the bandwidth used, but will not do any dynamic tone mapping whatsoever.

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