Keep One Audio Track in a Video
Pick a video with multiple audio tracks, choose the one to keep by index, and the extra tracks are stripped losslessly in your browser — nothing is uploaded.
About this tool
Some videos ship with more than one audio track — an original-language mix and a dub, a commentary track, a described-audio track, or a clean stereo alongside a 5.1 mix. Most players let you switch between them, but the extra tracks travel with the file forever, bloating its size and confusing apps that pick the wrong one by default.
This tool keeps exactly one audio track and drops the rest. You choose the
track by its 0-based index — 0 is the first audio track, 1 the second,
and so on — and the video plus the chosen audio are copied straight through
(-c copy), so there's no re-encode: the picture and the kept audio stay
byte-for-byte identical and the export is near-instant. Everything happens in
your browser with ffmpeg compiled to WebAssembly; the file never leaves your
device.
Worked example. Say you have movie.mkv with two audio tracks — track 0
is the foreign-language original and track 1 is the English dub. Set Audio
track to keep to 1, leave subtitles off, and you get a video that plays the
English dub everywhere, with the original-language track removed. Not sure which
index is which? Open the file in VLC (Audio → Audio Track) or run
ffprobe yourfile.mp4 — the audio streams are listed in order, and the first one
shown is index 0.
Works with MP4, MKV, MOV and WebM. Files up to 25 MB are supported in the
browser; larger files are better handled by the gizza CLI. If you pick a track
index the video doesn't have (for example 1 on a file with a single audio
track), the export fails with a clear "matches no streams" error rather than
producing a silent file.
FAQ
How do I find out which audio track number I want?
Audio tracks are numbered from 0 in the order they appear in the file. The
quickest way to see them is ffprobe yourvideo.mp4, which lists each stream —
the first Audio: line is index 0, the next is 1, and so on. In VLC, the
Audio → Audio Track menu lists them top to bottom in the same order. Pick the
position (starting at 0) of the one you want to keep.
Does this re-encode the video or lose quality?
No. Both the video and the audio track you keep are stream-copied (-c copy),
so nothing is re-compressed — the output is byte-for-byte identical in quality to
the source, just without the extra audio tracks. That also makes the export very
fast, since there's no encoding step.
What happens to subtitles and other tracks?
By default only the video and your one chosen audio track are kept; subtitle, chapter and data tracks are dropped. Tick Also keep subtitle tracks to copy any embedded subtitles through as well. Subtitle copying is skipped without error when the file has none.
Can I keep two audio tracks at once?
No — this tool keeps exactly one audio track by design (that's how it shrinks a multi-track file down to a single, unambiguous audio stream). If you need to keep a different single track, just run it again with a different index.
Is my video uploaded anywhere?
No. The whole thing runs locally in your browser using ffmpeg compiled to WebAssembly. Your video is never sent to a server, so it stays private and there's no upload wait — only the size of your own file matters.
Developer & Automation Access
Run it from the terminal
Same engine as this page, headless — via the gizza CLI:
gizza tool video-audio-track-selector 'url=https://example.com/input' 'track=0' 'keep_subtitles=true'New to the CLI? Get gizza →
Open it by URL
Pre-fill and auto-run this tool with query parameters — the names match the API/CLI:
https://gizza.ai/tools/video-audio-track-selector/?url=https://example.com/input&track=0&keep_subtitles=trueMachine-readable descriptor: tool.json — title + parameters JSON Schema for agents.