Mirelo, a Berlin-based AI startup, has raised $41 million in a seed round led by Index Ventures and Andreessen Horowitz to tackle a key gap in AI-generated video: the lack of synchronized audio. The company specializes in adding realistic sound effects and music to AI-created videos, a feature that has been largely missing from most current tools. Mirelo’s latest product, Mirelo SFX v1.5, uses AI to analyze video content and generate matching sound effects in real time. The model interprets visual cues—like footsteps, door slams, or car engines—and automatically pairs them with appropriate audio, creating a more immersive experience. The release of this tool caught the attention of investors betting on the next wave of generative AI innovation, particularly in gaming and creative content. Despite being in stealth mode until recently and operating with limited resources, Mirelo has already faced competition from major players. Companies like Sony, Tencent, Kuaishou’s Kling AI, and ElevenLabs have launched similar video-to-SFX models. However, Mirelo differentiates itself through its focused approach and technical precision. CEO and co-founder CJ Simon-Gabriel says the startup is building a competitive moat by concentrating on high-quality, context-aware audio generation—a space with less research and fewer established players than AI image or text generation. To scale its operations, Mirelo plans to more than double its current team of 10 employees by the end of next year. The new funding will support hiring in research and development, product development, and go-to-market strategy. The company has already made its models publicly available on platforms like Fal.ai and Replicate, with API usage expected to be a primary revenue driver in the near term. Mirelo is also developing Mirelo Studio, a creator workspace designed to support professional workflows. While still in early stages, the platform aims to become a full-featured environment for video creators who want to add audio without needing advanced technical skills. The startup is mindful of the ongoing debate around training data in generative AI. Index Ventures’ Georgia Stevenson noted that Mirelo uses a combination of public and licensed sound libraries and has established revenue-sharing agreements with artists and rights holders. This approach aims to respect intellectual property while building sustainable models. Mirelo’s pricing targets amateur creators and prosumers, offering a freemium model with a recommended plan at €20 per month ($23.50). Simon-Gabriel emphasizes that audio is not just an add-on—it’s essential. “George Lucas said sound is 50% of the movie-going experience. It’s not an overstatement. You can take exactly the same images, and the sound will shape a completely different ambience,” he said. With both founders being AI researchers and musicians, Mirelo also has plans to expand into AI music generation. But for now, sound effects remain the primary focus, driven by strong market demand and less crowded competition. The company’s total funding now stands at $44 million, including a previous pre-seed round led by Atlantic. Mirelo has also attracted high-profile angel investors, including Mistral’s CEO Arthur Mensch, Hugging Face’s Thomas Wolf, and Fal.ai’s Burkay Gur, adding credibility and potential partnerships. While other AI video tools, like Google’s Gemini with DeepMind’s Veo 3.1, are beginning to integrate audio, Simon-Gabriel sees this as validation. “Now, suddenly, people realize, ‘Oh, maybe we should add sound.’ But of course, you should. It’s like silent movies versus talkies—there’s a huge difference.”