Mirelo raises $41M to tackle AI video’s missing sound
Mirelo raises $41M in new funding to solve a problem many creators immediately notice when using AI video tools: silence. While generative video has advanced rapidly, audio has lagged behind, leaving many clips feeling unfinished or artificial. The Berlin-based startup is building AI models that automatically add sound effects and soundtracks synced to on-screen action. The new capital comes from Index Ventures and Andreessen Horowitz, two firms betting big on the future of generative media. The round underscores how audio is emerging as the next competitive frontier in AI video. For creators, studios, and game developers, sound may determine whether AI video feels usable or forgettable. Mirelo’s backers clearly believe the company is well positioned to fill that gap.
Credit: Index VenturesWhy AI video still struggles with audio
Most AI video generators focus on visuals first, assuming sound can be added later through manual editing. That assumption breaks down for fast-moving creators who want end-to-end automation. Sound effects must match motion, timing, and mood, or the illusion collapses. Without audio, AI videos often feel flat, even if the visuals look impressive. Mirelo’s core insight is that sound is not an accessory but a structural component of storytelling. By training models to interpret what’s happening in a video, the startup aims to generate audio that feels intentional rather than generic. This approach turns sound design into a real-time, AI-driven process. For many users, it could remove one of the biggest friction points in AI video creation.
Inside Mirelo SFX and its early traction
Earlier this year, Mirelo released Mirelo SFX v1.5, an AI model designed specifically for video-to-sound effects generation. Instead of producing music alone, the model focuses on environmental and action-based sounds. Footsteps, impacts, ambient noise, and motion cues are automatically aligned with what’s happening on screen. This narrow focus helped Mirelo stand out in a crowded generative AI landscape. According to investors, the product’s clarity attracted attention from gaming and media companies exploring faster production workflows. By solving one specific problem well, Mirelo gained credibility despite being a relatively young startup. That traction helped set the stage for its unusually large seed round.
Index and a16z bet on a new AI category
The $41 million seed round, led by Index Ventures and Andreessen Horowitz, signals confidence in a new category: video-native audio AI. Investors see generative sound as a natural extension of generative visuals, especially in games and interactive media. Large tech companies have already released video-to-audio models, validating the market’s importance. But Mirelo’s backers believe specialization matters in the early stages of category creation. Rather than competing broadly, the startup is focused on outperforming generalist models on realism and sync. This strategy aligns with how previous AI infrastructure winners emerged. The size of the round also gives Mirelo time to iterate without rushing to monetize prematurely.
Competing with giants in video-to-SFX AI
Mirelo enters a space where major players like Sony, Tencent, ElevenLabs, and Kuaishou-owned Kling AI are already active. Many of these companies have deeper pockets and established distribution. Mirelo’s advantage lies in focus and speed rather than scale. While larger firms ship multipurpose models, Mirelo is optimizing for one outcome: believable sound effects tied tightly to visuals. This narrow scope allows faster experimentation and refinement. However, staying competitive will require rapid execution as rivals improve. The new funding gives Mirelo the resources to hire aggressively and close performance gaps. In AI, technical lead times can be short, making execution critical.
Scaling the team and the technology
At the time of the funding, Mirelo had a team of about 10 people. CEO and co-founder CJ Simon-Gabriel says that number could double or even triple by the end of next year. New hires will focus on research, product development, and go-to-market strategy. Expanding the team is essential to keep pace with competitors and customer demand. The company is also investing heavily in model quality and reliability. For creators, even small audio mismatches can break immersion. Mirelo’s roadmap prioritizes consistency, lower latency, and broader sound libraries. Scaling responsibly is now one of the startup’s biggest operational challenges.
APIs first, creators next
In the short term, Mirelo expects most revenue to come from API usage. Its models are already available through platforms like Fal.ai and Replicate, making them easy for developers to integrate. This approach aligns with how many AI infrastructure companies grow: developers first, creators later. At the same time, Mirelo is building its own creator-facing workspace, Mirelo Studio. The goal is to support more professional use cases over time. By owning both the API and the interface, the startup can learn directly from user behavior. That feedback loop may prove valuable as AI video workflows mature.
Addressing training data and artists’ rights
As generative AI faces scrutiny over data sourcing, Mirelo and its investors are proactively addressing the issue. According to Index Ventures, the company trained its models using public and purchased sound libraries. Mirelo is also signing revenue-sharing partnerships designed to respect artists’ rights. This approach aims to avoid the legal and ethical pitfalls that have plagued other AI startups. While tensions remain inherent in generative tools, transparency is becoming a competitive advantage. For enterprise customers, data provenance matters as much as performance. Mirelo’s stance could help it win trust in regulated or brand-sensitive environments.
Who Mirelo is really building for
Despite its ambitious vision, Mirelo is not trying to replace professional sound designers overnight. Its freemium model includes a creator plan priced at €20 per month, targeting amateurs and prosumers. These users want fast results without complex audio editing tools. For them, AI-generated sound is an enabler, not a shortcut to Hollywood-quality production. Mirelo’s tools help unmute AI videos that would otherwise go unused. Over time, the company may move upmarket, but its current focus is accessibility. This strategy mirrors how many creative platforms gain traction before expanding into professional workflows.
Why sound could decide AI video’s future
Mirelo raises $41M at a moment when AI video quality is improving faster than audiences can adapt. As visuals become easier to generate, differentiation shifts to realism and emotional impact. Sound plays a decisive role in both. As Simon-Gabriel notes, sound shapes how viewers interpret the same images. In that sense, audio is not secondary but transformative. If Mirelo succeeds, it could redefine how creators think about AI video production. For investors and users alike, the message is clear: the next phase of generative video will be heard, not just seen.
