Add Audio to Video Tool

Merge, replace, or mix audio tracks with your videos - fast and easy!

Advertisement

Video Preview

Audio Track

Audio Settings

📹 Keep full video - Video stays at full length (00:00.000). Audio will be added starting at 00:00.000 for 00:00.000 duration.

New audio will replace the original video sound

Adjust audio loudness (100% = original)

Universal compatibility

Better quality

Ultra-fast processing with stream copy (limits some effects)

💡 Quick Guide

  • Step 1: Upload your video and audio files
  • Step 2: Set video time range (where audio will play)
  • Step 3: Set audio time range (which part to use)
  • Step 4: Full video kept, audio added at selected position
  • Tip: If audio is longer than video, it auto-trims to fit!
  • Fast mode: 10x quicker with stream copy enabled
  • Mix mode: Combines both audio tracks (takes longer)

Why Use PixDuplicate Video Audio Merger?

Seamless Audio-Video Integration

Combine video and audio files with precision timing controls to create perfectly synchronized multimedia content for any purpose

Ultra-Fast Processing

Leverage intelligent stream copy technology for dramatically faster processing when no audio effects or re-encoding is required

Advanced Audio Controls

Fine-tune audio levels with volume adjustment, apply professional fade effects, and choose between replacement or mixing modes

Complete Privacy Protection

Your media files remain entirely on your device - all processing occurs locally within your browser for maximum security

Flexible Audio Modes

Replace original audio completely or intelligently mix new audio with existing tracks for professional results

Multiple Format Support

Work with various video formats (MP4, WebM, MOV) and audio formats (MP3, WAV, AAC, OGG) with flexible output options

How The Video Audio Merger Functions

Combining your media files has never been more efficient or secure

Step 1: Upload your video and audio files

Select your source video and audio files by dragging and dropping or using the file browser. PixDuplicate supports multiple video formats (MP4, WebM, MOV, AVI) and audio formats (MP3, WAV, AAC, OGG, M4A) up to 2GB for video and 500MB for audio.

Start with our example files to immediately test the merging capabilities without any uploads!

Step 2: Configure timing and audio settings

Customize how your media will be processed:

Precise Timing: Set exact start and end points for both video and audio segments

Volume Control: Adjust audio levels from 0% to 200% for perfect balance

Audio Mode: Choose between replacing original audio or mixing with new audio

Fade Effects: Apply professional fade-in and fade-out transitions

Step 3: Select processing method and output format

Determine how your merged media will be optimized:

Ultra-Fast stream copy for compatible files (no re-encoding needed)

Balanced processing for standard encoding with effects

High-quality encoding for maximum output quality

Choose between MP4, WebM, or MOV output formats

Step 4: Process and download your merged video

Once processing is complete:

Preview your merged video with integrated audio playback

Download your file with optimized naming convention

View detailed processing statistics including method and time

Reprocess with different settings if needed

Speed Tip: Use Ultra-Fast mode when simply replacing audio without effects - process 30-minute videos in under 10 seconds!

Your Media Privacy Matters

Unlike other online video editing services, PixDuplicate processes everything locally within your browser. This ensures:

Your video and audio files never leave your device
No server uploads or cloud processing
No registration or personal information required
Completely free with no usage limitations
No watermarks on your processed videos
Works offline after initial page load

Rated 4.9/5 by Video Creators Worldwide

Join thousands of content creators who trust PixDuplicate for video-audio merging

4.9

Based on 298 reviews

Chandler Davis

"This saved my podcast production workflow! Being able to quickly replace audio in video recordings without re-encoding is absolutely incredible."

8/14/2024

Paige Stewart

"The ultra-fast mode is mind-blowing when you just need to replace audio. Processed a 30-minute video in literally 8 seconds!"

3/22/2025

Spencer Walsh

"I use this weekly for adding music to my tutorial videos. The privacy aspect is crucial for my unpublished content and client work."

11/28/2024

Morgan Fitzgerald

"The audio mixing feature works perfectly for my interview videos where I need to balance voice and background music. Professional results!"

9/17/2025

Taylor Greene

"As a video editor, I appreciate the precision timing controls. Being able to set exact start points for both video and audio is essential for my work."

5/11/2026

Casey Robbins

"Used this to fix the audio on my wedding video. The fade effects made the audio transitions seamless and incredibly professional looking."

10/3/2026

Frequently Asked Questions

What video and audio formats are supported?

PixDuplicate supports MP4, WebM, MOV, and AVI video formats, along with MP3, WAV, AAC, OGG, and M4A audio formats. You can output to MP4, WebM, or MOV formats with various quality settings to match your needs.

What's the difference between stream copy and full encoding?

Stream copy is an ultra-fast method that directly copies video and audio streams without re-encoding, which can process files in seconds. However, it only works when replacing (not mixing) audio and when no audio effects are applied. Full encoding is slower but supports all effects and mixing capabilities.

Can I mix audio instead of replacing it completely?

Yes! When your source video contains audio, you can choose to either replace it completely with your new audio file or mix both audio tracks together. Mixing allows you to combine voiceovers with background music or add sound effects while preserving original audio. Note that mixing requires full encoding.

Are there any file size or duration limitations?

You can process video files up to 2GB and audio files up to 500MB. There's no strict limit on duration, though extremely long files may take more processing time depending on your device's capabilities and the selected processing method.

How does PixDuplicate ensure my files remain private?

All processing happens locally in your browser using WebAssembly technology. Your files are never uploaded to any server or cloud service - they stay entirely on your device throughout the entire process, ensuring complete privacy and security for sensitive or proprietary content.

Why would I need to add audio to video?

Adding audio to video is essential for numerous scenarios: adding voiceovers to tutorials, replacing poor-quality original audio, adding background music to video clips, creating multimedia presentations, syncing separately recorded audio with video footage, or adding sound effects to silent videos.

Does the tool preserve video quality?

Yes! When using stream copy mode, your video quality remains completely unchanged since no re-encoding occurs. Even when full encoding is necessary for effects or mixing, we use high-quality compression settings to minimize any quality loss.

Can I adjust audio volume and add fade effects?

Absolutely! You can adjust the volume of your added audio from 0% to 200% of the original level, allowing you to make audio louder or softer as needed. You can also apply fade-in and fade-out effects with customizable durations for smooth, professional audio transitions.

What happens if my audio is longer or shorter than the video?

You have complete control over timing. Use the start and end time settings to trim both video and audio to the exact lengths you need. If audio is shorter than video, you can set it to loop, or simply have silence after the audio ends. If audio is longer, it will be trimmed to match your video duration.

Can I use this tool for commercial projects?

Yes! PixDuplicate is completely free to use for both personal and commercial projects. There are no watermarks, no attribution requirements, and no licensing restrictions. You own all rights to the videos you create using our tool.

Discord logo

Need Assistance? Join Our Discord!

If you're unsure how our website works or need help finding duplicate images or using our image compression tool, or have any suggestions for improvement, don't hesitate to join our Discord server.
Product Hunt logo

Share Your Feedback on Product Hunt!

If you have any suggestions for improving our website, or if you'd like to let us know what you think about our features, feel free to leave your feedback on Product Hunt. Your input helps us grow and serve you better!