Convert MP4 to OGA — Free Online Tool
Convert MP4 video files to OGA audio format, extracting the audio stream and re-encoding it to Vorbis inside an Ogg container. This is ideal for stripping video from MP4s to produce open-format, royalty-free audio files compatible with open-source media players and web applications.
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FFmpeg Command
Copy this command to run the same conversion locally with FFmpeg on your desktop. Download FFmpeg
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Settings
Note: Browser-based encoding uses approximate quality targets. For precise CRF compression, copy the FFmpeg command above and run it on your desktop.
Estimated output:
Conversion Complete!
DownloadHow It Works
During this conversion, FFmpeg discards the video stream entirely — no video data is carried into the output. The audio stream from the MP4 (typically AAC or MP3) is decoded and then re-encoded using the libvorbis encoder into Vorbis format, wrapped in an Ogg container with the .oga extension. Because AAC and Vorbis are fundamentally different codecs, a full transcode of the audio is required — this is not a simple remux. The re-encoding introduces a generation of lossy compression (if the source audio was already lossy AAC), so quality is determined by the Vorbis quality scale setting. Any subtitle tracks are dropped, and only a single audio track is carried over, since OGA does not support multiple audio tracks.
What Each Flag Does
| Flag | What it does |
|---|---|
ffmpeg
|
Invokes the FFmpeg command-line tool. In this browser-based tool, it runs via FFmpeg.wasm compiled to WebAssembly, so no file ever leaves your machine — the same binary and flags work identically when run locally on your desktop. |
-i input.mp4
|
Specifies the input file — your source MP4, which may contain H.264 or H.265 video alongside AAC, MP3, or Opus audio streams. FFmpeg reads all streams from this container before deciding what to encode into the output. |
-c:a libvorbis
|
Sets the audio codec to libvorbis, the reference encoder for the Vorbis format. This decodes the MP4's audio stream (typically AAC) and re-encodes it as Vorbis — a fully open, patent-free codec — wrapped in the Ogg container. Video streams are automatically discarded because the output format (OGA) is audio-only. |
-q:a 4
|
Sets the Vorbis encoder quality level to 4 on a scale of 0–10, which targets approximately 128 kbps variable bitrate. This is the default balance between file size and audio fidelity, suitable for most music and speech content; increase to 6–8 for higher-fidelity archiving or reduce to 2–3 for smaller voice-only files. |
output.oga
|
Defines the output filename with the .oga extension, signaling an audio-only Ogg container. FFmpeg infers from this extension that the output should use the Ogg muxer with no video stream, producing a file compatible with open-source players like VLC, Audacious, and HTML5 browsers that support the Ogg Vorbis audio type. |
Common Use Cases
- Extract a music track or soundtrack from an MP4 music video to produce a distributable Vorbis audio file for open-source or Creative Commons platforms
- Convert recorded lecture or webinar MP4 files into lightweight OGA audio for podcast publishing on platforms that accept Ogg Vorbis feeds
- Strip audio from MP4 screen recordings to create standalone audio commentary or tutorial narration files
- Prepare audio assets in open, royalty-free Vorbis format for use in HTML5 web games or browser-based applications that use the Web Audio API
- Archive audio content from MP4 home videos in an open-standard container to avoid dependence on proprietary codec licensing
- Extract interview or dialogue audio from MP4 footage for transcription workflows that accept Ogg-based audio input
Frequently Asked Questions
Yes, some quality loss is expected because both AAC (typically used in MP4) and Vorbis are lossy codecs, and converting between two lossy formats means the audio undergoes a second compression pass. The degree of loss depends on the Vorbis quality setting — the default quality level of 4 (roughly 128 kbps variable bitrate) preserves most perceptible audio detail for speech and typical music. If your source MP4 uses a very high AAC bitrate, the output Vorbis file will sound very close to the original at quality 4 or higher, but the conversion is not bit-for-bit transparent.
OGG is a generic Ogg container file extension often associated with Vorbis audio, while OGA is the formally recommended extension specifically for audio-only Ogg files (defined by the Xiph.Org Foundation). Both use the same underlying Ogg container format, so the file structure is identical — only the extension differs. Using .oga clearly signals that the file contains audio only, with no video stream, which helps media players and web servers handle the file correctly.
Common metadata fields like title, artist, album, and date are generally preserved during the conversion, as FFmpeg maps compatible tags from the MP4 container's iTunes-style metadata to Ogg's Vorbis comment tag format. However, some MP4-specific metadata fields (such as chapter artwork or iTunes podcast-specific tags) may not have direct equivalents in the Vorbis comment schema and will be dropped. It is worth inspecting the output file's tags with a tag editor if precise metadata preservation is important.
The OGA format supports only a single audio track, so FFmpeg will select the default (first) audio stream from the MP4 by default. If your MP4 contains multiple audio tracks — for example, a director's commentary track alongside the main audio — only the primary track will be included in the output. If you need a specific non-default track, you can modify the FFmpeg command to add '-map 0:a:1' (replacing '1' with the zero-indexed track number you want) before the output filename.
The quality is controlled by the '-q:a' flag, which accepts integer values from 0 to 10 for the Vorbis encoder. The default is 4 (approximately 128 kbps variable bitrate). Increasing the value — for example, '-q:a 7' or '-q:a 9' — produces higher quality and larger files, while lowering it (such as '-q:a 2') reduces file size at the cost of audio fidelity. For archiving music, values of 6–8 are commonly recommended; for voice-only content, values of 3–5 are usually sufficient.
Yes. On Linux or macOS, you can run a shell loop such as: 'for f in *.mp4; do ffmpeg -i "$f" -c:a libvorbis -q:a 4 "${f%.mp4}.oga"; done'. On Windows Command Prompt, use: 'for %f in (*.mp4) do ffmpeg -i "%f" -c:a libvorbis -q:a 4 "%~nf.oga"'. Both approaches apply the same Vorbis encoding settings to every MP4 in the current directory, which is particularly useful for large collections that exceed the browser tool's 1GB per-file limit.
Technical Notes
The Vorbis codec used in OGA output is a fully open, patent-free audio codec maintained by Xiph.Org, making OGA files free of the licensing considerations associated with AAC (the default codec in most MP4 files). The libvorbis encoder uses a variable bitrate (VBR) model controlled by the '-q:a' scale rather than a fixed bitrate, so file sizes will vary based on audio complexity — a quiet speech recording at quality 4 may be significantly smaller than a dense orchestral soundtrack at the same setting. OGA does not support video, subtitles, or multiple audio tracks, so all of these are silently dropped during conversion. Chapter metadata is technically supported by the Ogg container and FFmpeg will attempt to transfer it, though player support for Ogg chapters is inconsistent compared to MP4. The Ogg container also natively supports streaming via its page-based structure, making OGA files suitable for progressive HTTP playback in compatible web players.