Recording

This page covers installing and setting up what the demo recorder needs before its first take. Recording, the chapter on making videos, covers the takes themselves.

Requirements

1. A MIDI port the DAW listens on. This is the IAC bus, as MIDI Setup describes, with a Live set holding a MIDI track for each channel used. The first track of a set plays on channel 1, the second on channel 2 and so on, so a Live set with a track listening to IAC Driver Bus 1 on each of channels 1 to 4 covers a demo with four tracks. Each Live track's Monitor switch must be set to In. A take through FluidSynth needs none of this.

2. A loopback audio device. A Mac can't record what comes out of its speakers by itself, so the recorder records from BlackHole 2ch, a free, open-source loopback device. Install it from the project folder:

   sh user_scripts/install_blackhole.sh

   The script uses Homebrew, offering to install it first, and asks before installing BlackHole, an audio driver, for which macOS asks your password and restarts the audio; it does nothing when BlackHole is installed already, and ends by saying how to make the Multi-Output Device below. BlackHole can also be installed by hand from https://existential.audio/blackhole/, the 2-channel build. After installing, macOS may ask you to allow the driver in System Settings under Privacy & Security.

3. A Multi-Output Device, so that you hear the DAW while the take is recorded. In Audio MIDI Setup, press + at the bottom left, choose Create Multi-Output Device, and tick your speakers or headphones and BlackHole 2ch. Tick Drift Correction on BlackHole. In the DAW's audio preferences, choose that Multi-Output Device as the output. The DAW now plays into your speakers and into BlackHole at once, and the recorder reads BlackHole.

4. Screen Recording permission for your terminal program. The first take asks for it; after allowing it in System Settings under Privacy & Security, quit and reopen the terminal, since the permission reaches new processes only.

5. Xcode's command line tools, which most Macs that build software already have, for the swift command the recorder uses once per take to find BlackHole's id:

   xcode-select --install