# Video Smart Mux

Combine video with external audio using copy mode.

> Canonical page: https://elysiatools.com/en/tools/video-smart-mux

- **Category:** Media

- **Keywords:** video, mux, audio, copy

## Overview

Muxes one video stream and one audio stream into a single file.

## Inputs

- **Video File** (file)
- **Audio File** (file)
- **Output Container** (select)

## When to use

- When you have a high-quality video track and a separate high-fidelity audio track that need to be merged without losing quality.
- When you want to replace the existing audio track of a video file with a newly recorded or translated voiceover.
- When you need to quickly combine video and audio streams into a specific container format like MKV, MP4, or MOV without waiting for time-consuming re-encoding.

## How it works

- Upload your primary video file containing the video stream you want to keep.
- Upload the external audio file containing the audio track you want to merge.
- Select your preferred output container format (MKV, MP4, or MOV).
- Run the tool to mux the streams together instantly using copy mode, generating a single combined file.

## Use cases

- Merging a clean screen recording video with a separately recorded studio microphone audio track.
- Adding localized audio dubbing tracks to an existing video file.
- Combining raw camera footage with external field recorder audio files.

## Frequently asked questions

### Does this tool re-encode my video or audio?

No, the tool uses copy mode to mux the streams directly, preserving original quality without re-encoding.

### What output formats are supported?

You can choose to output your merged file as an MKV, MP4, or MOV container.

### Can I upload files larger than 100MB?

No, the maximum file size limit for both the video and audio inputs is 100MB.

### Will the original audio in the video file be kept?

The tool replaces the audio stream of the video file with the newly uploaded external audio file.

### Why is the muxing process so fast?

It is fast because it copies the data packets directly instead of decoding and re-encoding the media streams.

## Related tools

- [Duplicate Audio Library Finder](https://elysiatools.com/en/tools/audio-duplicate-library-finder): Find exact and near-duplicate audio across uploaded files or a ZIP, including copies saved with different codecs.
- [Stream Passthrough Trimmer](https://elysiatools.com/en/tools/stream-passthrough-trimmer): Stream-copy trimming.
- [Video Audio Replace](https://elysiatools.com/en/tools/video-audio-replace): Replace the audio track in a video file with a new audio file while keeping the original video
- [Video Audio Volume](https://elysiatools.com/en/tools/video-audio-volume): Adjust the audio volume in a video file by increasing, decreasing, or normalizing sound levels
- [Video SRT Softmux](https://elysiatools.com/en/tools/video-srt-softmux): Add selectable SRT subtitles without burning them in.
- [Video Reverse](https://elysiatools.com/en/tools/video-reverse): Reverse video playback (play backwards) with optional audio reversal
- [Extract Center Channel](https://elysiatools.com/en/tools/audio-center-channel-extract): Extract the center channel from a surround audio file or video audio track
- [Audio Spectrogram Generator](https://elysiatools.com/en/tools/audio-spectrogram-generator): Generate a spectrogram image from an audio file or a video audio track

## Samples

- [WebRTC Real-Time Communication Samples](https://elysiatools.com/en/samples/webrtc-samples): Comprehensive WebRTC samples for peer-to-peer audio/video communication, data channels, screen sharing, and signaling server implementation
- [Bevy Game Engine Samples](https://elysiatools.com/en/samples/bevy-samples): Bevy Rust game engine examples with ECS, 2D/3D graphics, audio, and game mechanics implementations
- [Godot Engine Samples](https://elysiatools.com/en/samples/godot): Godot Engine examples including 2D/3D games, GDScript, C#, and engine features
- [Arduino Development](https://elysiatools.com/en/samples/arduino): Comprehensive Arduino development examples including microcontroller programming, sensor and actuator control, robotics projects, and real-time system design

## Related content

- [Stream Copy, Remux, and Media Packaging Tools](https://elysiatools.com/en/hubs/stream-copy-remux-and-media-packaging): Compare probe, remux, trim, mux, soft-subtitle, cover-art, and batch rewrap tools in one hub for low-CPU media packaging workflows.
- [Audio Encoding and Format Conversion Tools](https://elysiatools.com/en/hubs/audio-convert): Compare audio format conversion, bitrate changes, sample-rate conversion, codec swaps, and export tools in one hub for delivery and archive workflows.
- [Audio Editing and Cleanup Tools](https://elysiatools.com/en/hubs/audio-utility): Compare audio trimming, silence removal, fades, mixing, and denoise tools in one hub for podcast, voiceover, and music cleanup workflows.
- [Video-to-Audio and Animation Conversion Tools](https://elysiatools.com/en/hubs/video-convert): Compare tools that turn video into audio, extract video streams, and convert between short-form video and animated image formats in one hub.