# Video Dual Audio Merger Mux two audio tracks into one video in copy mode. > Canonical page: https://elysiatools.com/en/tools/video-dual-audio-merger - **Category:** Media - **Keywords:** dual audio, mux, copy ## Overview Builds a dual-audio file with optional language and title metadata. ## Inputs - **Video File** (file) - **Primary Audio File** (file) - **Secondary Audio File** (file) - **Output Container** (select) - **Primary Audio Language** (text) - **Secondary Audio Language** (text) - **Primary Track Title** (text) - **Secondary Track Title** (text) ## When to use - When you want to add a secondary language track or commentary track to an existing video file. - When you need to combine separate video and audio recordings into a single multi-track file without losing quality through re-encoding. - When preparing dual-audio media files for players that support switching between multiple language tracks. ## How it works - Upload your source video file along with the primary and secondary audio files. - Select your preferred output container format, either MKV or MP4. - Specify the language codes and track titles for both audio streams to ensure proper identification in media players. - Process the files to mux the audio tracks directly into the video container using copy mode. ## Use cases - Creating dual-language movies or educational videos with switchable English and Japanese audio tracks. - Adding a director's commentary track as a secondary audio option alongside the main movie audio. - Muxing high-quality external microphone recordings and backup audio tracks into a single video file. ## Frequently asked questions ### Does this tool re-encode the video or audio? No, it uses copy mode to mux the tracks, which preserves the original quality and processes the files quickly. ### What output formats are supported? You can export the final dual-audio video as either an MKV or MP4 file. ### Can I label the audio tracks with specific languages? Yes, you can set three-letter language codes (like 'eng' or 'jpn') and custom titles for both tracks. ### Is there a file size limit for the uploads? Yes, the video and audio files must each be under 100 MB. ### Can I add more than two audio tracks? No, this tool is specifically designed to merge exactly one primary and one secondary audio track into the video. ## Related tools - [Video Audio Extract Enhanced](https://elysiatools.com/en/tools/video-audio-extract-enhanced): Extract audio from video files with advanced options - multiple formats, quality settings, and audio enhancement - [Video Stream Extractor](https://elysiatools.com/en/tools/video-stream-extractor): Extract audio and/or video streams from a video file using stream copy (no transcoding) after probing stream availability - [Video to AAC Converter](https://elysiatools.com/en/tools/video-to-aac): Extract audio from video and convert to AAC format - [Video to FLAC Converter](https://elysiatools.com/en/tools/video-to-flac): Extract audio from video and convert to FLAC (lossless) format - [Video to MP3 Converter](https://elysiatools.com/en/tools/video-to-mp3): Extract audio from video and convert to MP3 with bitrate, resampling, and channel options - [Video to Opus Converter](https://elysiatools.com/en/tools/video-to-opus): Extract audio from video and convert to Opus format - [Video to WAV Converter](https://elysiatools.com/en/tools/video-to-wav): Extract audio from video and convert to WAV (PCM) with optional resampling and channel selection - [Media Metadata to JSON](https://elysiatools.com/en/tools/media-metadata-to-json): Extract audio/video metadata as JSON with ffprobe. ## 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 - [Copyright-Free FLAC Audio Samples](https://elysiatools.com/en/samples/flac-samples): Lossless FLAC audio samples for testing and development, mirrored from MP3 set with nature sounds and meditation music - [Copyright-Free MP3 Audio Samples](https://elysiatools.com/en/samples/mp3-samples): Collection of royalty-free audio samples for testing and development purposes including nature sounds, meditation music, and ambient audio ## 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. - [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. - [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.