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Arlen Holder Arlen   Holder is offline
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Default Typical first pass tutorial process on Windows 10 where NONE of the extent how to articles actually tell you what you really need to do!

On Thu, 05 Nov 2020 12:04:18 -0500, Paul wrote:

What's needed to record the output, is a path to get
back to the input side, and to the ADC.

The Stereo_Mix method, uses a wire which is inside
the HDAudio chip. Selecting that input, is a matter
of configuring software the right way, so it will work.

Every input has a level adjustment. You are adjusting
the level to avoid overloading while recording. You adjust
the gain, so the recording is loud enough.

Take for example, you play a DVD and get a LineOut output that way.
DVDs seem to be recorded really low, like -15dB or so.
There seems to be no way to drive a lot of signal that way.

When recording that DVD with Audacity, you need to adjust
the level, for a pleasant recording. Audacity has a VU meter,
so you can see the incoming voltage level. The VU Meter is
there, so you can judge whether you've still got headroom,
for a non-distorted recording.

Inputs have mutes. Or, a level slider can be set at zero.
The effect is zero volts on input and a very quiet recording,
if either of those happen.

*******

There is no particular reason for an interaction between
LineOut/LineIn and Stereo_Mix.

When you plug the 1/8" plug into a jack, the jack has a
side contact. The side contact closure is detected on the
HDAudio chip. It generates an event to the OS. The driver
presents a prompt "Did you plug something into LineIn?"
or similar.

One of the side effects of plugging in LineIn, is it can
be used to automatically switch the input mux in front
of the ADC, so that LineIn is used. And whatever your
previous choice was, is de-selected.

The loopback path only exists for one chip choice at a time.
To record through the RealTek Stereo_Mix, means the RealTek
LineOut has to be used and playing the content on the
analog computer speakers or similar. If the sound was
going to your TV set over HDMI for example, maybe the
NVidia video card HDAudio internal to the GPU is doing that.
And there would be no "virtual wire" to get to the
RealTek ADC/Mux.

As a consequence, you have to think carefully about where
that wire is.

There is at least one "virtual cable" driver, which is a
software technique for copying the Windows (output) mixer
stream and making a "pin" of it. Then, in Audacity, the "pin"
is offered as an "input choice". The virtual cable, in a
sense, bypasses DACs and ADCs and "just gets the job done".
This would be an alternative if someday soon, Microsoft
finds a way of permanently removing the driver ability
to get at the Stereo_Mix which is a hardware feature.
From a DMCA perspective, Microsoft could also choice to
block and prevent that "virtual cable" software from
running.

Summary: Plugging in 1/8" plugs to HDAudio jacks, has
as a side effect, the "side contact" signals to the
driver, that a change has occurred. And the driver
can use this as an excuse to switch input or output
settings, by signaling these facts to the OS handling
things. Without software to receive "plug events",
nothing would happen without software interference.

The Stereo_Mix doesn't need that. It needs selecting
Stereo_Mix in Audacity, to "wire up the input". But it
also needs a signal going through the output side
of that HDAudio chip, so that the signal can be copied.

Stereo_Mix and the black wire, are two of the same.
They're a path. The black wire also tickles the side
contact on two jacks. The Stereo_Mix does not, so to get
the Stereo_Mix to work requires two GUI actions
at a minimum. Something to set up the input side.
And some operation to get a signal onto the output,
so you can copy it with a feature put there in the
HDAudio chip for this.


All the while I thought the tutorials were missing only _one_ conditional
"if then else" check, without knowing there are (at least) five of them!

I've read your response four or five times, like a kindergarten kid
watching a Disney movie, where each time I get a little bit more of what
you're trying to inform me (as all this "Stereo Mix" stuff is new to me).

This is perhaps the _simplest_ definition of "Stereo Mix" I've found:
"Stereo Mix allows you to record exactly what was being output to your
speakers, without going through any analog/digital conversion."
https://mediarealm.com.au/articles/stereo-mix-setup-windows-10/

But Lord knows I've been scouring the Internet for better definitions:
https://mediarealm.com.au/articles/stereo-mix-setup-windows-10/
https://winbuzzer.com/2020/04/25/how-to-record-windows-system-audio-with-stereo-mix-xcxwbt/
https://www.howtogeek.com/howto/39532/how-to-enable-stereo-mix-in-windows-7-to-record-audio/

*It seems 5 planets need to line up for a successful stereo mix recording.*

(1)
You need to turn on app & desktop app access to the "so-called" microphone:
o Win+R ms-settingsrivacy-microphone == Microphone access = on

(2)
Your audio driver must be able to enable/disable the Stereo Mix selection:
o Win+R devmgmt.msc Sound video & game controllers == Update driver
https://www.realtek.com/en/component/zoo/category/pc-audio-codecs-high-definition-audio-codecs-software

(3)
You need to enable Stereo Mix (apparently, disabled by default in Win10):
o Win+R mmsys.cpl Recording Stereo Mix == Enabled

(4)
You need your recording software to be able to use Stereo Mix
o Audacity:Edit Preferences Devices Recording == Stereo Mix

(5)
And, you need to connect the "loopback" of LineOut to enable copying:
o Plug in any 1/8-inch male plug into the lime green LineOut connector

It's in understanding that final (fifth) planet lining up that I keep
reading (and re-reading) your response, gleaning a bit more with each try.