# Add Audio to Video Free: Replace or Mix Music in MP4 - [Home](/) - - - [Tools](/tools/) - - - Add Audio to Video # Add Audio to Video: Replace or Add Background Music Put a song, a voiceover or the sound from another clip on any video. Swap out the original soundtrack or mix the two at the volumes you choose, then download an MP4. Your files are processed in this browser tab and never uploaded. ## 1. Video Drop a video here, or click to choose MP4 - MOV - MKV - WebM - up to 2 GB Choose file ## 2. Audio to add Drop an audio file (or a video with the sound you want) MP3 - M4A - WAV - FLAC - OGG - up to 2 GB Choose file Your video and audio never leave your device. If your browser has no AAC encoder of its own (Firefox and most Linux browsers), one is downloaded from dragbin.com the first time the audio needs converting. Only add music you have the right to use, especially if you plan to publish the video. AAC encoding (in browsers without a built-in AAC encoder) by [FFmpeg's libavcodec](https://ffmpeg.org/) ([LGPL-2.1-or-later](https://ffmpeg.org/legal.html)), loaded as a separate file only when needed. Free to UseNo hidden chargesNo Software InstallationRuns in your browserNo Sign UpStart instantly ## Keep every version Store the original footage and each soundtrack version in DragBin, encrypted on your device before it's uploaded. DragBin protects files with [client side](/client-side-encryption/), [quantum resistant encryption](/post-quantum-encryption/) (ML-KEM + AES-256) keeping sensitive data private with a [zero knowledge](/zero-knowledge-encryption/) security architecture. - Get 5GB quantum resistant storage forever - Unlimited sharing, unlimited bandwidth and unlimited file size uploads - Integrated Global CDN and preview media in 4k/8k [Try DragBin Today](https://dragbin.com) ## How to Add Music to a Video Two files in, one video out. Change the settings and run it again as often as you like. Step 1 Choose your video, then the audio to add: an MP3, M4A, WAV, FLAC or OGG file, or another video whose sound you want. Step 2 Pick Replace or Mix, set when the new audio starts and what happens if it's shorter than the video. Step 3 Press Add audio, watch the preview, and download the MP4. ## Why Add Audio Here? Changing a soundtrack shouldn't cost you picture quality or an upload. ### Picture Left Untouched The video stream is copied as it is, never re-encoded, so every frame matches your original. ### Fast Plain Replace Replacing the sound with an MP3 or AAC file copies both streams straight into the new file, so it finishes in seconds. ### Mix, Loop and Fade Keep the original voices under new music, loop a short track to fill a long video, start it later, or fade it out at the end. ## Private by Design Home videos, client edits and unreleased tracks stay on your device. ### No Uploads Both files are read and combined inside this browser tab. Neither is sent to a server. ### Works on Phones Too Runs in current Chrome, Edge, Firefox and Safari. A plain replace with MP3 or AAC audio even works in older Safari. ### Any Common Video MP4, MOV, MKV and WebM videos all come back as an MP4 that plays almost everywhere. ## Try DragBin Today Pair private, in-browser file tools with zero-knowledge, quantum-resistant cloud storage. 5GB free, forever. [Claim 5GB free storage (opens in new tab)](https://app.dragbin.com/signup) ## Frequently Asked Questions ### Does adding audio lower the video quality? No. The picture is copied into the new file exactly as it is, without re-encoding. Only the sound changes. If you simply replace the soundtrack with an MP3 or AAC (.m4a) file, that audio is copied untouched as well. ### Are my files uploaded? No. The video and the audio are read and combined inside your browser tab and never sent to a server. The only download is an AAC encoder from dragbin.com, and only when your browser lacks its own and the audio needs converting. ### What's the difference between Replace and Mix? Replace removes the video's original sound and keeps only the new audio. Mix keeps the original sound and plays the new audio on top, with a volume slider for each (0 to 150%). Mixing decodes both soundtracks, so it takes longer than a plain replace and gently limits peaks so the result doesn't clip. ### What happens if the music is shorter or longer than the video? Longer music is cut where the video ends. If it's shorter, you choose: keep the full video with silence (or only the original sound) after the music ends, loop the music to fill the video, or end the video where the music ends. You can also add a 2-second fade-out so the music doesn't stop abruptly. ### Which files can I use, and what do I get back? Videos can be MP4, MOV, MKV or WebM; the audio can be MP3, M4A/AAC, WAV, FLAC, OGG/Opus, or another video whose sound you want. You always get an MP4 named with "-with-audio" added. AVI, WMV and Apple Lossless (ALAC) files can't be read in the browser. ### Is there a length limit, and does it work on my phone? A plain replace has no length limit beyond the file size (2 GB on a computer, 500 MB on a phone or tablet). Mixing, looping, delaying or fading holds the soundtrack in memory, so those are limited to 20 minutes of video on a computer and 5 minutes on a phone. Converting audio needs Chrome, Edge, Firefox or Safari 26; a plain replace with MP3 or AAC audio also works in older Safari. More free tools ## Keep going with the DragBin toolbox [ ### Remove Audio from Video Just want silence? Strip the sound from a video without re-encoding it. ](/tools/mute-video/)[ ### MP4 to MP3 Pull the soundtrack out of a video and save it as an MP3. ](/tools/mp4-to-mp3/)[ ### Merge Audio Files Join several songs or clips into one track before adding it to your video. ](/tools/merge-audio/) --- Canonical: https://www.dragbin.com/tools/add-audio-to-video