# Playout Development & Testing

## Testing with virtual audio devices

It is possible to do testing with purely virtual audio devices. This comes in handy if testing on hosts without any
audio hardware is required. There are different options for virtual audio devices that can be enabled through the `.env`
file of `aura-playout`. Setting them to `1` enables them, commenting them out or setting them to `0` disabled them.

##### AURA_ENGINE_VIRTUAL_OUTPUT
If enabled creates a pipewire null-audio-sink `virtual_line_out_0` which is automatically linked to `engine-cores` output.

##### AURA_ENGINE_VIRTUAL_OUTPUT_LINK_AURA_RECORDER
If enabled links the `virtual_line_out_0` to `engine-recorder` allowing purely virtual block recordings.
This requires `engine-recorder` to use jack as source_format in `engine-recorder.yaml`.
In addition pipewire needs to be enable for `engine-recorder` by using the pipewire docker-compose overwrite:

```bash
COMPOSE_FILE=docker-compose.yml:docker-compose.pipewire.yml
```

#### AURA_ENGINE_VIRTUAL_INPUTS
If enabled 5 virtual line-in pipewire null-audio-sinks `virtual_line_in_0,1,2,3,4` are created and linked to `engine-core`s line-in channels.
It is then possible to play audio to these line-in channels using `pw-play --target virtual_line_in_0,1,2,3,4` or similar commands.

#### AURA_ENGINE_VIRTUAL_INPUTS_PLAY_TEST_AUDIO
If enabled test audio is played in a loop on each virtual line in. The audio is a voice saying "This is line-in X".