In article ,
Paul wrote:
Dave Plowman (News) wrote:
Before I start chasing things - ie RTFM - should the HDMI feed from a
graphics card also be capable of carrying system audio? On Win10, if it
helps.


If you put your mind to it, you can come up with a way to be
holding an HDMI connector in hand, which has no audio.

But normally, up to 8 channel LPCM can be carried.
And LPCM (linear pulse code modulation), is just
straight samples, with no A-law, u-law, or compression
scheme. There is plenty of bandwidth on HDMI, so it's not
pinched for bandwidth like SPDIF was.

Video cards generally come in three generations. For the
longest while, there was no audio at all, associated with
video cards.

The first video card with sound, actually relied on the
user running the SPDIF signal from the sound chip on
the motherboard, over to a connector on the top edge of
the NVidia video card.

https://www.geeks3d.com/20080810/gef...ctor-tutorial/

Then, and only then, did some flavor of digital audio go
across HDMI. It's possible DisplayPort didn't even exist yet.
Since SPDIF had limited bandwidth, you would not expect to
be running 8 channel LPCM with that generation of hardware.
SPDIF is 2 or 4 channel, with 4 channel being, um, nonexistent.
And running AC3 would ruin the effect (it's compressed).

The era today, the "CODEC" if you will, is on the video card.
It no longer relies on SPDIF passthru as a mechanism. And
more audio channels are available as a result. The logic block
that does it, might be considered HDAudio of some sort. Or
maybe it declares itself that way.

AMD chose a different route to get audio on theirs. The driver
package (the jumbo video driver), had a RealTek folder on it,
and the suspicion was, that AMD had bought an intellectual
property block from RealTek, to implement the HDAudio function.
It's not clear today, whether they're using an in-house design
and have dumped the RealTek interim solution. AMD is also rumored
to have bought a USB3 block for their Southbridge, rather than
design their own. These are time savers and mean hiring fewer
"specialists" to make stuff.

*******

https://www.audioholics.com/hdtv-for...-hdmi-versions

HDMI 1.0 December 2002 8-channels of 192kHz/24-bit audio (PCM)

HDMI 1.1 May 2004 + high resolution audio format???

HDMI 1.2 August 2005 + DSD (Direct Stream Digital), + Super Audio CD (SACD)

HDMI 1.2 December 2005

HDMI 1.3 June 2006 + native Dolby TrueHD and DTS-HD Master Audio streams
for external decoding by AV receivers

HDMI 1.3a November 2006
...
HDMI 2.0 September 2013 + Up to 32 audio channels
Up to 1536kHz audio sample frequency

Just because the standards say this, does not mean the computer
industry immediately implemented this "with haste". The passthru
SPDIF idea was particularly egregeous (it smacked of "we don't
give a ****"). I'm not aware of anyone wiring that up, so I don't
even know if it works (that's because the SPDIF output from
sound chips, is TTL level and not cable level, and the signal
might not be standardized well enough to be connecting it up!).
But once the video card got the onboard CODEC, that's when
people started using it.

You can start by checking whether a suitable "digital audio" item
is in the playback choices in Windows. I have some with the
word "NVidia" on mine. But no equipment to test with (no fancy
monitors or TV sets). The video card was purchased for OpenCL
or CUDA compatibility, and for the video SIP block (video
encoder). I tried cracking a password on the video card, but
the software said it would "take 13 years" :-)

Thanks for the excellent explanation Paul. An HDMI cable from my laptop
to the TV carries audio just fine. But with the desktop here, it's not so
easy to try without moving TVs around. But it is a new and pricey MB and
graphics card so you've given me the hope to actually try it. The laptop
does identify the TV as a selectable sound output in the windows settings.

--
*A conclusion is the place where you got tired of thinking *

Dave Plowman London SW
To e-mail, change noise into sound.