Runway | Mirelo SFX 2.0 Adds Video-Guided Sound to MCP
Runway added Mirelo SFX 2.0 to MCP on October 15, 2026. An agent can take a clip and a description of the desired sound, then return a separate audio track for the edit. For creators finishing generated or silent footage, it offers a way to develop sound around the picture already chosen.
Build sound around the action in the clip
Mirelo's video-guided approach uses the footage to generate effects aligned with visible action, including footsteps, impacts and environmental sound. Text guidance can describe the intended character of the audio. In a production brief, this makes the distinction between the visible event and the desired listening experience particularly useful.
A shoe touching a surface needs a different sound depending on whether the scene should feel close, distant, delicate or heavy. Describe that intention before evaluating a take. The image establishes the event, but the editor still decides how prominent it should become within the sequence and what the viewer needs to notice.
Review synchronization before adding the music
Play the returned track against the clip without the final music first. Listen for the timing of important contacts, changes in movement and transitions between spaces. A well-chosen effect should feel connected to the action without needing to be unusually loud. Note the exact moment when a cue needs to move or change.
For a sequence of several clips, listen across the cuts as well as within each shot. Background ambience should support a coherent space when that is the creative intention. Compare the sound perspective with the picture: a distant subject and an intimate effect may communicate a different scene from the one the editor intended.
Keep the generated track available for mixing
A separate effects track gives the editor material to balance with dialogue, narration and music. Use that separation to judge whether the cue supports the main message. An opening impact might need emphasis, while a continuous background texture may work best when it is barely noticeable beneath the voice.
Test the mix on ordinary playback as well as headphones. Short social videos often need the important action to remain understandable on a small speaker. Make the final choice in the complete sequence, where competing sounds and the pace of the edit can change how a promising effect is perceived.
Check the connected account before a larger sound pass
The Runway integration is available on paid plans. MCP work uses the connected account's Runway credits, so confirm the available model and current cost in the working environment before assigning more clips. Keep the approved picture version with the selected sound so later changes can be checked against the same reference.
Begin with one representative shot that contains a clear action and a quieter background. That provides a useful comparison for both timing and restraint. Once a take is accepted, decide whether another clip needs the same sound character or a deliberate contrast before building the rest of the sequence.
Daisuki's Take: What This Means for Designers
We see this as a way to bring sound design into the same creative conversation as the footage. The picture gives the task a concrete reference.
We would listen for timing first, then for tone and prominence in the mix. A convincing effect can still be the wrong choice if it distracts from the message.
For editors, the separate track is useful material rather than a finished mix by default. Keep the final audiovisual decision in the context of the whole sequence.
Sources and Recommended Links
- Mirelo SFX 2.0 - October 15, 2026 | Runway Official Changelog
- Video-to-audio vs text-to-SFX | Mirelo Official Product Guide
- Runway MCP | Runway Official Product Page
