Add your MP4 file
Drop one or more .mp4 files onto the converter above, or browse for them. They load into browser memory only — nothing is uploaded, so there is no size-based pricing and no server queue.
MP4 to OPUS
Pulling the soundtrack out of a .mp4 video into .opus audio keeps what you can hear and drops the picture entirely. Free, private, and validated — the file never leaves your browser.
100% private for supported formats
Runs on your deviceConvert supported files
Drop MP4 files here
Batch files can each use a different output. Nothing uploads for local conversions.
Working inputs include camera RAW, browser-local audio/video, PDF, CBZ/CBR comics, office documents, ebooks, markup, 3D models, structured text, images, and archives.About converting MP4 video to Opus audio
Pulling the soundtrack out of a .mp4 video into .opus audio keeps what you can hear and drops the picture entirely. An .mp4 file is a multimedia container that bundles compressed video, audio, subtitles, and chapter data into a single stream-friendly package. It is the default delivery format for nearly every phone, camera, and video platform, which makes .mp4 the safest target when a clip has to play everywhere.
An .opus file contains audio compressed with the Opus codec, stored in an Ogg container. Opus represents the current state of the art in lossy audio, beating MP3, AAC, and Vorbis in listening tests at nearly every bitrate from whisper-thin speech settings up to transparent music encoding. For this route the practical draw is best-in-class efficiency at essentially every bitrate and royalty-free with an open reference implementation — balanced against older car stereos, AV receivers, and MP3 players have never heard of it, which is worth knowing before you commit a large batch.
Why convert MP4 to OPUS?
The usual reason to take .opus audio out of a .mp4 file is that only the sound matters — a talk, interview, song, or podcast segment. Keeping the video stream would waste storage, and a dedicated audio file is easier to trim, tag, and play. On the source side, fewer track, attachment, and chapter features than Matroska; on the target side, the payoff is best-in-class efficiency at essentially every bitrate, which is exactly what you want for compressing podcast and voice-chat audio to tiny files.
MP4 vs OPUS at a glance
| Aspect | MP4 video (.mp4) | Opus audio (.opus) |
|---|---|---|
| Format type | Container — quality depends on the codecs and settings inside | Lossy — discards detail it judges invisible to shrink files |
| How it stores data | typically carries H.264/AVC or H.265/HEVC video with AAC audio, though the box structure also accepts AV1, MP3, and timed-text tracks | the hybrid SILK/CELT design switches coding modes automatically based on content |
| Strongest at | publishing video to the web, social media, or a client who has not specified a format | compressing podcast and voice-chat audio to tiny files |
| Weak spot | fewer track, attachment, and chapter features than Matroska | older car stereos, AV receivers, and MP3 players have never heard of it |
| Metadata | iTunes-style metadata atoms (title, artist, cover art) plus XMP and per-track language tags; ID3 is not native to the container | vorbis comments in the OpusTags header, including cover art via METADATA_BLOCK_PICTURE, plus an output-gain field used for loudness normalization |
Pick OPUS as the output
Select .opus in the output menu next to each file. The menu only offers targets this engine can genuinely produce, so if OPUS is selectable, the route is real and validated.
Convert on your device
Press Convert. A WebAssembly FFmpeg build demuxes the audio track and re-encodes it locally; the video stream is simply discarded.
Verify and download
Each result is signature-checked before the download unlocks, so a failed encode can never masquerade as a valid OPUS file. Outputs keep the original filename with the .opus extension.
MP4 to OPUS questions, answered
Will converting MP4 to OPUS lose quality?
Since mp4 is container-oriented and opus is lossy-oriented, the conversion preserves the source content exactly as stored; no additional compression pass is applied beyond what .opus itself requires.
Is it private to convert MP4 files here?
Yes — the .mp4 file is processed inside your browser tab and never uploaded. A WebAssembly FFmpeg build demuxes the audio track and re-encodes it locally; the video stream is simply discarded. Close the tab and the file is gone from memory.
Where will the OPUS file work?
Chrome, Firefox, and Edge have played Opus for a decade and Android supports it natively, while Safari initially accepted the codec only inside CAF or WebM wrappers before extending support to .opus files. Legacy hardware such as older car head units remains the real gap, and conversion to MP3 or AAC bridges it.
Will the OPUS file be bigger or smaller than my MP4?
Much smaller — the video stream is usually 80–95% of a .mp4 file's weight, and it is discarded entirely. The remaining audio is re-encoded at the bitrate implied by your quality setting.
What happens to the metadata in my MP4 file?
This converter strips container metadata deliberately (the FFmpeg command runs with metadata mapping disabled) so exported files do not leak recording details. In the source, iTunes-style metadata atoms (title, artist, cover art) plus XMP and per-track language tags; ID3 is not native to the container; none of it is transmitted anywhere because the file never leaves your browser.