Upload audio + image → MP4 with correct duration.
Whether you're a musician sharing your latest track on Facebook, a podcaster turning episodes into shareable clips, or a content creator making lyric videos — converting an MP3 audio file into a video with a static image is one of the most searched tasks online today. This guide explains everything you need to know, including why most free converters fail and how our tool actually works correctly.
This is one of the most frustrating problems users encounter. You upload your audio, wait for the conversion, and then the downloaded MP4 shows zero duration in media players and on social media. The video appears broken. The technical reason: most browser-based converters use an API called MediaRecorder. This records a canvas stream in real-time and saves it as a WebM file — not a real MP4. WebM files created this way lack duration metadata because the recorder can't know in advance how long the video will be. Media players see this and display 0:00 or cannot seek through the video. Our tool uses a different approach (mp4-muxer + WebCodecs) which produces true MP4 files with all metadata intact, including exact duration, bit rate, and codec information.
Facebook does not allow direct audio uploads — you must use a video format. Here's the exact workflow thousands of creators use every day:
Yes, it is completely safe. Because our converter uses WebCodecs and mp4-muxer running entirely in your browser, your audio and image files are never uploaded to any server. The entire conversion process happens on your own device. We do not collect your files, do not store conversion history, and do not require any account or login. Your creative work stays private.
Unlike MediaRecorder which has to record the canvas in real-time (a 5-minute audio takes 5 minutes), our encoder processes frames as fast as your device can handle – typically 10–30 seconds for a 5-minute file. That's up to 30 times faster.
Last updated: 2026 — PinSaving Free Media Tools