Add / Replace Audio in Video
Add background music or replace video audio tracks.
Trim, crop, compress, convert, rotate, extract frames, merge videos, and replace audio in one seamless flow!
Your files and data are processed locally and never leave your device.
Drop Audio File Here
Supports MP3, WAV, OGG, M4A, FLAC, AAC • 100% Client-side Processing
What is Add / Replace Audio in Video?
Add Audio to Video lets you add background music, voiceovers, or replace the existing sound in any video clip. Mix original video sound with a new audio track or replace the audio entirely with precise volume controls.
Unlike legacy online utilities that upload sensitive media and documents to remote cloud storage, Shadow Toolkit executes this entire operation directly within your browser's local runtime. Your raw data never crosses the network.
Key Capabilities
- Add background music tracks (MP3, WAV, OGG) to video clips
- Option to replace original audio or mix both audio tracks with volume sliders
- Precise start offset controls to sync music with specific video scenes
- Hardware-accelerated audio and video multiplexing
- 100% private in-browser execution
Common Use Cases
How to use Add / Replace Audio in Video
Upload Video & Audio
Select your video file and your audio soundtrack.
Mix Volume Levels
Adjust the volume balance between original video sound and new music.
Download Finished Video
Save your completed video with the new soundtrack.
Download Media Asset
Preview the rendered media in the in-browser player and click 'Download' to save the finished audio/video file locally.
Frequently Asked Questions
Yes. Toggle 'Loop Audio' to repeat the soundtrack until the video finishes.
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