The DR HDMI 8K manual (Rev 1.2) rates the unit for HDMI 2.1 up to 48Gbps at FRL6, often quoted as 1500MHz. Its highest listed formats are 4K120 4:4:4 10-bit, 8K60 4:2:0 10-bit and 8K30 4:2:2 12-bit, plus DSC-compressed formats.
FRL levels and the lane math behind them
For its higher modes, HDMI 2.1 replaces TMDS with Fixed Rate Link (FRL) signaling. Each level sets a lane count (3 or 4) and a speed per lane:
- FRL1: 3 × 3Gbps = 9Gbps
- FRL2: 3 × 6Gbps = 18Gbps
- FRL3: 4 × 6Gbps = 24Gbps
- FRL4: 4 × 8Gbps = 32Gbps
- FRL5: 4 × 10Gbps = 40Gbps
- FRL6: 4 × 12Gbps = 48Gbps
These are gross rates; 16b/18b coding leaves a little less for payload. Uncompressed 4K120 4:4:4 10-bit needs a 40Gbps-class link (FRL5), as does 8K60 4:2:0 10-bit, which is why the predefined 8K60 tables and 4K120 4:4:4 tables are labeled FRL-5. TMDS in HDMI 2.0 stops at 18Gbps.
Reading the live link on the OLED and web page
With an FRL signal present, the default OLED page shows the incoming FRL rate plus RX and TX status. The web server MAIN section adds the lane count and Gbps per lane, so you can see whether the link runs at the rate the format needs.
Capping FRL, VRR and ALLM in the EDID
In [COPY TX SINK EDID and MODIFY] mode, the video flags disable FRL or cap the rate offered to the source at FRL1 to FRL5; VRR and ALLM are simple on/off switches. Lowering the cap shows quickly whether an unstable 4K120 picture settles at a lighter rate. Flags change only what is advertised, not what the hardware can do.
Cables for 48Gbps links
For 48Gbps links the manual asks for a 1500MHz certified or tested 8K HDMI cable, copper or fiber, on both the input and output side. The unit recovers the signal, but it cannot restore data a cable never carried.
Stepping down to locate the limit
If a 4K120 4:4:4 table (17–22) drops out, try 4K120 4:2:0 (23–28) or a 4K60 4:4:4 600MHz table (29–34). When the lighter setting holds, suspect a bandwidth limit rather than a handshake fault. Restart the source after each change.
Frequently asked questions
What is the highest 4K120 format the DR HDMI 8K lists?
4K120 4:4:4 at 10-bit. The manual does not list 4K120 4:4:4 at 12-bit.
Which chroma format does the DR HDMI 8K use for 8K60?
The manual lists 8K60 4:2:0 10-bit as the maximum, and every predefined 8K60 table is 4:2:0 FRL-5.
Where can I see the FRL rate of the current signal?
On the default OLED info page, and in the web server MAIN section with lanes and Gbps per lane.
Where to buy
The DR HDMI 8K is available from HDFury.eu.