Bug in HDMI 2.1 chips: AV receivers, next-gen consoles and graphics cards affected

After the market launch of HDMI 2.1 dragged on for years, Denon, Marantz and Yamaha presented the first audio / video receivers with the new version of the audio / video interface in the past few months – just in time for the introduction of the next-generation Xbox Series consoles from Microsoft and Sony’s PlayStation 5 (PS5) as well as from Nvidia’s RTX 30 series graphics cards. The new devices output videos in 4K resolution with 120 frames per second (4K120 for short) or even in 8K with up to 60 Hertz (8K60) with full color resolution and increased contrast range (HDR) via HDMI 2.1.

As c’t reports in the current issue of c’t 23/2020, a suspected breakdown of the chip manufacturer Panasonic Solutions (meanwhile taken over by Nuvoton Technology) ensures that, according to the current state of knowledge, all HDMI 2.1-compatible receivers from Denon, Marantz and Yamaha are not able to transfer videos in these ultra-high resolutions to the TV without errors with certain players. The TV screen then remains black due to the HDMI 2.1 glitch.

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According to research by c’t, this problem also affects receiver models that are currently still in development – including the avantage models from Yamaha, which have been expected for a long time. Onkyo / Pioneer and Sony are also said to have bought the aforementioned HDMI chips from Panasonic Solutions; these companies have not yet announced any AV receivers with HDMI 2.1.

C’t encountered the problem during a test of a pre-production model of the Xbox Series X. The car racing game “Dirt 5” ran in the c’t laboratory on the LG CX9 TV with a direct connection in 4K120 with HDR, with the detour via Denons HDMI 2.1 compatible AV receiver AVR-X2700H, however, did not transfer this ultra-high resolution with increased contrast range from the console to the TV as advertised. The transmission of video images from the preview model of the Xbox Series X to the television was only possible without problems in resolutions that do not require HDMI 2.1.

According to Microsoft, the pre-production model of the Xbox Series X is already based on the final hardware. But c’t will test the retail version again with regard to the problem.

Similar problems arose with an Nvidia RTX-3080 card – here, too, a TV set connected via the AV receiver did not deliver a 4K image with 120 Hertz and HDR. With the PS5, the transmission should work according to c’t information; c’t has not been able to verify this so far.

Since Yamaha uses the same chipset for its devices, its devices are also likely to be affected. The company had advertised in a press release that both next-generation consoles could be connected to the new AV receivers at the same time thanks to multiple HDMI 2.1 inputs. The new receivers from Denon and Marantz only have one HDMI 2.1 input.

c’t received the information from several industry insiders that Panasonic Solutions made an error in the implementation of the “Fixed Rate Link” (FRL) transmission variant introduced with HDMI 2.1, which cannot be corrected by a firmware update. The article in c’t 23/2020 goes into this in detail – as well as the workarounds that are now being considered and the problems that exist with their implementation. The delivery of faultless replacement chips will probably take some models until the middle of next year.


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