OldGuy said:
OldGuy submitted this idea :
Fixed it but ...
The correct drivers must have already been there, but the Win Sound
options did not talk about anything relevant to HDMI.
I have those little pastel colored round connectors on the front and
back panels and i was offered only those choices.
So I fiddled around finally selecting the rear little round connectors
and then I had sound through the HDMI cable. Who woulda thought.
As Vanguard was saying, some older video cards use the passthru
cable method, rather than having a "sound chip" on the video card
itself.
The passthru cable is S/PDIF format, and connects to the top of the
video card. On the motherboard side, it would be the four pin
header. Since motherboard makers are "afraid" of doing full S'PDIF
I/O, but are happy to do just the output function, and the four
pin header can do that. AFAIK, the version of S/PDIF on the motherboard,
is single ended TTL, and not a low amplitude transformer-drive
friendly signal. The motherboard header typically goes to some
sort of conversion circuit (slot plate interface, I have one).
In the case of the video card passthru, the video card is only
too happy to use the digital signal level on the four pin header.
(You cannot take the four pin header directly to your Marantz receiver.)
http://en.wikipedia.org/wiki/S/PDIF
Lots of motherboards don't have the S/PDIF four pin header, and then
the video card passthru method is not an option. No HDMI sound for you...
Until you buy a later video card, that is.
Selecting a round dot in the custom sound control panel, routes
sound samples to S'PDIF at 6Mbit/sec, and from there the GPU
converts the digital stream, into stuff that HDMI can use. So
some motherboard sound chips, have both analog round dots (green
for Line Out), but they also have a selector for the S/PDIF dot.
And then up through the passthru cable, to the top of the video card.
*******
If your video card has the sound chip, then go to the bar at the
bottom of your WinXP screen. Look for the round speaker icon.
Right click. Select "Adjust Audio Properties". Go to "Audio"
tab. Look at Sound Playback pulldown menu. If your motherboard
has sound and the video card has sound, the pulldown menu will
have two items. Selecting the video card HDMI from there,
should route sound playback, to the HDMI display speakers.
*******
A short history of HDMI sound:
1) Passthru cable. Typically an NVidia feature. ATI might have been later.
Use custom sound control panel for onboard sound, to route sound samples
to the video card.
2) Onboard sound on video card. ATI may have been first. In this generation,
a RealTek! driver was used, implying the sound generation hardware was
purchased as an IP block from RealTek. And this is in line with the ATI
philosophy of "buy rather than build". They don't want to train up a
team to write audio drivers, on the first day. So for a while, if you
looked into the driver issue, the driver had RealTek branding.
3) Finally, all companies running on all cylinders. All video cards have
HDMI sound (should at least do some number of LPCM channels for free).
The video card driver has an own-branded driver of some sort
(no matter who really wrote it). So it now gives the appearances of
a properly done job.
For (2) and (3), the Sound and Audio Device Properties, is where you
select either onboard analog or video card HDMI sound. If you have
multiple other audio cards in PCI or PCI Express slots, they could
be listed in the menu too.
Paul
