Steam Machine HDMI 2.1 Support: The Display Standard Drama Explained
▼ Summary
– Valve’s upcoming Steam Machine hardware supports HDMI 2.1, but its spec sheet currently lists HDMI 2.0 due to incomplete software support in SteamOS.
– The HDMI Forum has blocked open source implementations of HDMI 2.1, preventing full feature support in the Linux-based AMD drivers used by SteamOS.
– This restriction has forced Valve to validate the hardware’s HDMI 2.1 capabilities using Windows during testing.
– Valve is actively working to overcome these software limitations to enable full HDMI 2.1 functionality on SteamOS.
– Through a technique called chroma sub-sampling, Valve has already increased the output beyond HDMI 2.0 limits to achieve 4K at 120Hz on the spec sheet.
The upcoming Steam Machine from Valve has sparked discussion among gamers regarding its display output capabilities, specifically its listed support for the HDMI 2.0 standard. While the hardware itself is capable of HDMI 2.1, software limitations within the Linux-based SteamOS are currently preventing full implementation. This situation stems from a broader industry conflict, as the HDMI Forum, which controls the official specifications, has explicitly blocked any open-source implementation of the HDMI 2.1 standard. This policy directly impacts the open-source AMD graphics drivers that SteamOS relies on, making it impossible for them to legally include certain features exclusive to the newer HDMI 2.1 specification.
An AMD engineer, Alex Deucher, previously confirmed this roadblock, stating that creating an open-source HDMI 2.1 implementation would violate the HDMI Forum’s requirements. Consequently, Valve has faced significant challenges in delivering the full hardware potential through its preferred operating system. The company has had to validate the Steam Machine’s HDMI 2.1 capabilities using Windows during its testing phases. Regarding the SteamOS experience, Valve representatives have stated they are actively working to find solutions and “unblock things” on the software front.
In the meantime, Valve has employed a technical workaround to enhance the machine’s output beyond standard HDMI 2.0 limits. The official HDMI 2.0 specification caps 4K output at 60 Hz. However, Valve has utilized a technique called chroma sub-sampling to achieve the “4K @ 120Hz” performance listed on the Steam Machine’s spec sheet. This method reduces color data to free up bandwidth, allowing for the higher refresh rate, albeit with a potential, often imperceptible, compromise in color resolution compared to a full, uncompressed HDMI 2.1 signal. The company’s efforts highlight the ongoing tension between proprietary standards and open-source development in the gaming hardware space.
(Source: Ars Technica)
