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Date:      Sat, 15 Sep 2018 20:45:01 +0200
From:      Polytropon <>
To:        Steven Friedrich <>
Cc:, "Steve O'Hara-Smith" <>
Subject:   Re: No Sound
Message-ID:  <>
In-Reply-To: <>
References:  <> <> <> <>

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On Sat, 15 Sep 2018 01:49:51 -0400, Steven Friedrich wrote:
> OK, I've figured out the basics (mostly)
> I have three possible outputs to choose from, i.e., pcm0 (rear analog), pcm1 
> (front analog), and pcm2 (HDMI/DP).
> I can choose which touse with sysctl hw.snd.default_unit.
> Which ever I set, I must use the corresponding mixer, i.e., mixer0 for pcm0, 
> mixer1 for pcm1, and mixer2 for pcm2.


> I can hear sound out of pcm0 and pcm1 (rear and front analog), but I can't 
> hear any sound from pcm2 which goes to HDMI.
> The man page for snd_hds says:
> HDMI and DisplayPort audio may also require support from video driver.
> Since I'm using syscons, I don't think this applies.

Correct. But... you mentioned that you're using FreeBSD 11.2,
and this should default to vt as the console driver, _not_ sc.
Anyway, I think in this case an X-related driver is meant.
And of course your video _hardware_ needs to support HDMI
audio. There are monitors which do not have this ability.
Some only offer an external audio connector (for headphones
or amplifier), and some have built-in amplified speakers.

> But it begs the question, is the audio supplied to both HDMI and DisplayPort 
> or is it selectable?

Maybe there is a corresponding setting in your computer's
CMOS setup (BIOS or UEFI). I would _guess_ that the system
choses the one output (out of the available two) that has
a device connected to it as the default unit for output.
At least that would be a sane approach. But... sure, you
never know... ;-)

> And is it digital or analog?

In those two cases, the audio is transmitted as digital data,
if I remember correctly. Turning it back into usable analog
audio is the task of the hardware attached to the other end
of the HDMI or DP cable.

> In summary, I can't get audio out to HDMI...

Maybe this is helpful:

There is a paragraph that deals with HDMI output, but the
task of _selecting_ it has been solved, so the question
that remains is: Why is there nothing to hear?

It is very important to check which graphics card your
system has (because that's the unit responsible for the
HDMI port), and see if there is a good X driver for it.
Of course sound and graphics hardware may actually be
inside the same chip, so "card" often doesn't apply.
It still seems to imply that HDMI sound playback is
only possible from within X...


Magdeburg, Germany
Happy FreeBSD user since 4.0
Andra moi ennepe, Mousa, ...

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