EDID and capabilities
EDID overflow
When there is no room left in the EDID
In short
The point at which a rewritten display description no longer fits the space the standard allows, so something you asked for is quietly left out.
An EDID is not a list you can keep adding to. It is a fixed number of bytes, and the more capabilities you force into one, the more likely something else quietly falls out of it.
An EDID has a hard size. The base block is 128 bytes, and a television adds a CEA-861 extension block of another 128. After the four byte header of that extension, and after the detailed timing descriptors that have to sit at the end of it, there are only about a hundred bytes left for the collection of data blocks that describe everything a modern chain cares about.
Everything competes for those bytes. Each supported video format costs a byte in the video data block. Each audio format costs three in the audio data block, so a sink claiming Dolby Digital, DTS, Dolby Digital Plus, TrueHD and DTS-HD Master Audio has spent fifteen before speaker allocation is written. Colorimetry, HDR static metadata, the HDMI vendor specific block and a Dolby Vision vendor specific block each want several more.
Overflow is what happens when the total no longer fits. Something has to be left out, and nothing announces which. The symptom is not an error but an absence: a format you deliberately forced never appears, or an audio format the amplifier used to receive stops arriving. Adding a second extension block is not a reliable escape, because plenty of sources read only the base block and the first extension.
Where this bites on the HDfury Diva
Automix is where you are most exposed, because it builds an EDID out of the real capabilities of the connected sinks and then applies your forced flags on top. Those flags are additive by design: the manual describes the BT.2020, HDR10, HLG and Dolby Vision flags as adding a capability only if it is missing, and as never removing one the sink already declares. Every flag you tick can therefore only make the result larger, and there are fourteen of them.
The flags that shrink it are the ones to reach for when something has gone missing. no 3D, set edid 3dremove on, drops the 3D structures. no YCbCr, set edid yuvremove on, removes the YCbCr claims and forces RGB. DV Remove, set edid dvremove on, takes the Dolby Vision block out altogether, and DV Limit 300MHz keeps Dolby Vision but only at the lower clock. In CUSTOM mode the same idea applies to the tables: the 90 predefined ones come in All Sound, SPDIF and Stereo variants of the same video format, and the SPDIF or Stereo variant describes far fewer audio formats.
Checking what actually went out
Do not assume the EDID your sources received is the one you designed. DOWNLOAD ACTIVE EDID TABLES in the EDID section saves the EDID from any input or output, so you can read back what was really presented. EXPORT CONFIG in the CONFIG section is the fuller record: it contains the EDID mode, the Automix algorithm, the table assigned to each input, every forceable flag, and the complete raw EDID of every input and output as full hex dumps. Compare that against what you asked for, then use ISSUE HOTPLUG to make the sources read the corrected EDID again.
Related terms
In the manual
The pages of the HDfury Diva manual where this comes up.