# Inputs

| Message                 | Description                                                                                   | Arguments |
| ----------------------- | --------------------------------------------------------------------------------------------- | --------- |
| `/mixeffect/usk/inputs` | Sets the fill and key sources for the selected Upstream Keyer in the selected Mix Effect Bus. | Multiple  |

| Argument    | Type    | Description                                          |
| ----------- | ------- | ---------------------------------------------------- |
| Fill Source | Integer | Video Source ID for the fill source.                 |
| Key Source  | Integer | Video Source ID for the key source.                  |
| USK         | Integer | One-based index of the Upstream Keyer. Default is 1. |
| M/E         | Integer | One-based index of the Mix Effect Bus. Default is 1. |