I just joined this thread but the HDMI spec has included DSD since version 1.2 and this is confirmed by the ability of disc players to output DSD to AVRs and prepros. AFAIK, the issue is that the feature set for HDMI output from computers does not include DSD. Probably the fault of the manufacturers of the HDMI hardware components in these devices.
Indeed.
I took a long journey down this particular rabbit hole about 9 months ago. I was playing SACDs from an old Sony UDP that I had bought used for ripping (prior to resurrecting my old PS3 for ripping, which ended up requiring a replacement laser but is more stable for that task). My AVR supported native DSD, and so happily took via HDMI the DSD bitstreams from the UDP. But I had the ISO rips and dammit, why can’t I send the native DSD from a computer?
The lore was that Intel, ATI, and NVIDIA (I don’t know of other mainstream video cards for PCs that support HDMI, but if there are, those manufacturers too) honored Sony/Phillips restrictions that only a certified SACD player could send native DSD bitstream over HDMI. Ah, but I know and love Linux, let’s take a look at the source. And indeed, down in the kernel source code for HDMI support you’ll find evidence of DSD streaming support - passthru - according to the specs. But, it’s only stubs, pointers in data structures named such that I know that’s where streaming DSD support would go, but there’s no actual code.
Bummer. But then I stumbled on specs for the Zidoo Neo Alpha media player, which supports native DSD streaming over HDMI. This is an Android-flavor device, so it runs an Android-flavor Linux kernel and so if the GPL is followed and binary “blobs” aren’t used, one should be able to find that code. Sadly, even though Zidoo posts some GPL source code, they don’t post their kernel (which could be for a number of legitimate reasons).
I ended up discovering Oppos and more importantly, Oppo clones, which can stream native DSD (with the right firmware) to my AVR. My ISOs are served via NFS from my NAS, and I gave up on the PC quest.
I’ll note that Oppos and Oppo clones use a Mediatek SOC (ARM-based) running Linux, and one can telnet (or ssh with a firmware change) into the Linux system running there and poke around and try to reverse engineer stuff. And Zidoo players use a Realtek ARM chipset running Android Linux, so likewise. If there’s a will there’s a way to port that native DSD HDMI streaming support, but I now lack the will
.