For real-time lip-sync in Unity using Spine, Rhubarb Lip Sync is a popular choice, but it primarily generates baked animations that are then imported into Unity. This means that the lip-sync is pre-calculated and not dynamically generated in real-time. Rhubarb Lip Sync can be used to create animations in Spine that are then played back in Unity, but it does not provide real-time lip-sync capabilities directly within Unity.
As for the SALSA LipSync Suite, it is a paid asset that provides real-time lip-sync capabilities in Unity. However, its compatibility with Spine slots specifically would depend on how the asset is set up to interact with Spine animations. You may need to create a custom integration to ensure that SALSA can control Spine's mouth slots or attachments for real-time lip-sync.
If you are looking for a real-time solution, you might need to explore custom scripting or integration between Unity's audio analysis capabilities and Spine's animation system to dynamically adjust mouth shapes based on audio input.
