LoopIt7 1.3.0 - A way in from Windows

A way in from Windows

Since 1.2.0 a virtual output has been a box inside LoopIt7: you assigned programs to it and it
summed them. Nothing else on the machine could pick it, because a Windows audio device comes
from a kernel driver and no user mode program can add one.

It still cannot add one. What it can do is borrow a cable.

Press the link button on a box and choose a cable. The other program sends to one end of it,
LoopIt7 listens on the other, and what arrives lands in your box and leaves down its cables as
usual. From Discord's side it is simply a device in the list.

  Discord  ──▶  LoopIt7 Cable  ──▶  [ Stream ]  ──┬──▶  Headphones
                                                  └──▶  OBS

If the machine has no cable, the picker says so, explains what one is, and offers to fetch it.
A cable that arrives because LoopIt7 asked for it is named after the box it serves, so the name
in Discord's list is the name on your canvas. A cable that was already there keeps the name it
came with: it is written down in somebody's OBS scene and their Discord settings, and it is not
ours to change.

What is new

• Give a virtual output a way in. Bind a box to a cable and other programs can pick it as
  their output. The picker lists a cable's two ends as a pair, so nothing is guessed, and says
  which end LoopIt7 will listen on.
• Naming. A cable LoopIt7 installed reads as Your box (LoopIt7 · VB-Audio), and its other
  end as Your box pickup, so the two cannot be confused in a device list. Whoever made the
  driver stays credited. Uninstalling puts every name back.
• Cables that were already here are left alone. LoopIt7 only renames one that arrived
  because it asked. Same vendor is not enough: installing VB-Audio's plain cable is no licence
  to rename their A+B pack or VoiceMeeter's VAIO.
• Empty states. A machine with no cable gets an explanation and a way to fix it rather than
  an empty list.
• The feedback guard covers cables. A cable's recording end patched back to its own playback
  end is a loop with only a driver in the way, and Windows reports the two ends as unrelated
  devices, so nothing in the graph could see it before. It is refused now, however many boxes
  are in between.

Fixed

• One cable can now only be the way in to one box. Pointing a second box at a cable already in
  use would have fed the same audio to both.
• Removing a virtual output hands its cable back. It used to leave a Windows device still named
  after a box that no longer existed.
• A playback endpoint was recorded twice when noting which cables were already present, because
  it appears both as itself and as the loopback source that taps it.

Notes

Unlimited virtual outputs inside LoopIt7, but one per installed cable can be seen from Windows,
because a cable carries one thing at a time. The free VB-CABLE gives you one.

The download is unsigned. See the README for what signing a driver actually requires and why
the LoopIt7 cable of our own is not finished.