Convert FLAC to OGG — Free Online Tool
Convert FLAC lossless audio to OGG Vorbis using your browser — no uploads required. This tool transcodes your FLAC files into the open OGG container with a Vorbis audio stream, delivering excellent perceptual quality at significantly reduced file sizes.
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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
FLAC stores audio as a lossless compressed PCM stream, meaning every sample is preserved bit-for-bit from the original recording. When converting to OGG Vorbis, FFmpeg fully decodes the FLAC stream back to raw PCM audio, then re-encodes it using the libvorbis encoder at the specified variable bitrate quality level (defaulting to -q:a 4, which targets roughly 128–160 kbps). This is a lossy transcode: psychoacoustic modeling is applied to discard audio information deemed inaudible, so the resulting OGG file will be perceptually similar but not mathematically identical to the source. The output is wrapped in an OGG container, which natively supports Vorbis streams, chapter markers, and metadata tags.
What Each Flag Does
| Flag | What it does |
|---|---|
ffmpeg
|
Invokes the FFmpeg binary — the open-source multimedia processing engine that handles decoding the FLAC input, running the Vorbis encoder, and writing the OGG output. In this browser-based tool, FFmpeg runs locally via WebAssembly (FFmpeg.wasm) with no server involvement. |
-i input.flac
|
Specifies the input file as a FLAC audio file. FFmpeg reads and fully decodes the lossless FLAC stream into raw PCM audio samples, which are then fed into the Vorbis encoder for re-encoding. |
-c:a libvorbis
|
Selects the libvorbis encoder to produce a Vorbis audio stream, which is the primary and most compatible lossy audio codec used inside OGG containers. This is what distinguishes a standard OGG file from an OGG FLAC or OGG Opus file. |
-q:a 4
|
Sets the Vorbis variable bitrate quality to level 4 on a scale of 0–10, targeting approximately 128–160 kbps. This is the default balance between file size and perceptual audio quality — sufficient for music and voice at substantially smaller sizes than the FLAC source. |
output.ogg
|
Defines the output filename with the .ogg extension. FFmpeg uses this extension to automatically select the OGG container format, which wraps the encoded Vorbis audio stream along with any copied metadata tags. |
Common Use Cases
- Preparing a high-quality FLAC music archive for playback on Android devices or media players that support OGG Vorbis but have limited storage space
- Uploading background music or ambient soundscapes to a web-based game or interactive application that streams OGG Vorbis for broad browser compatibility
- Reducing the file size of a lossless FLAC podcast master before distributing episodes to listeners, while retaining perceptually transparent audio quality
- Converting FLAC rips of vinyl records into OGG files for use in open-source music players like Rhythmbox, Audacious, or VLC on Linux desktops
- Packaging audio assets for a Godot or other open-source game engine project, which natively imports OGG Vorbis files without additional plugins
- Shrinking a large FLAC audiobook collection for sideloading onto a portable device with limited internal storage while keeping dialogue clarity
Frequently Asked Questions
Yes — this conversion is lossy. FLAC is a lossless format preserving every audio sample, while Vorbis uses psychoacoustic compression to discard inaudible information. At the default quality level (-q:a 4, targeting ~128–160 kbps), most listeners cannot distinguish the result from the original in a blind test. However, once you convert to Vorbis you cannot recover the original lossless data, so keep your FLAC files if archival fidelity matters.
Replace the value after -q:a in the command. The Vorbis quality scale runs from 0 (lowest, ~64 kbps) to 10 (highest, ~500 kbps), with 4 as the default (~128–160 kbps). For example, use -q:a 6 for roughly 192 kbps or -q:a 8 for near-transparent ~256 kbps output. Higher values increase file size while improving audio fidelity; for music where you want to stay open-source but maximize quality, -q:a 7 or 8 is a common choice.
FFmpeg copies compatible metadata tags from the FLAC file's Vorbis Comment block into the OGG container's own Vorbis Comment metadata by default. Standard tags like TITLE, ARTIST, ALBUM, TRACKNUMBER, and DATE transfer cleanly. However, embedded cover art stored in a FLAC PICTURE block may not transfer automatically and could require the additional flag -map_metadata 0 or explicit mapping to ensure it is included in the output.
FLAC files, even though compressed, still contain the complete audio waveform and are typically 3–5× larger than a lossy equivalent. The Vorbis encoder at -q:a 4 targets roughly 128–160 kbps, whereas a typical CD-quality FLAC might be encoded at an effective 700–1000+ kbps equivalent. The size reduction you see — often 60–80% — comes entirely from the lossy compression step, not from any change in sample rate or channel count.
Native iOS and macOS support for OGG Vorbis is limited — Apple's built-in frameworks do not recognize the format, so OGG files will not play in the Files app, Music, or most default iOS players. Third-party apps like VLC for iOS or Vox can play OGG Vorbis. If Apple device compatibility is a priority, consider converting to AAC in an M4A container instead, which has native Apple support.
The command as displayed processes a single file. To batch convert in a Unix shell, you can use a loop: for f in *.flac; do ffmpeg -i "$f" -c:a libvorbis -q:a 4 "${f%.flac}.ogg"; done. On Windows Command Prompt, use: for %f in (*.flac) do ffmpeg -i "%f" -c:a libvorbis -q:a 4 "%~nf.ogg". Both approaches apply the same Vorbis encoding settings to every FLAC file in the current directory.
Technical Notes
The OGG container supports multiple audio codecs — libvorbis (lossy), libopus (lossy), and FLAC (lossless) — but this tool uses libvorbis as the default since it is the canonical and most widely supported OGG audio codec. Vorbis uses variable bitrate (VBR) encoding controlled by the -q:a parameter rather than a fixed bitrate, which means the actual file size varies depending on the complexity of the audio content. FLAC source files that contain multi-channel audio (e.g., 5.1 surround) should transcode correctly since libvorbis supports up to 8 channels, though compatibility with surround OGG playback varies by player. ReplayGain tags stored in the FLAC file may not automatically transfer to the OGG output, and if this is important for consistent playback volume across a music library, the tags should be recalculated after conversion using a tool like loudgain. Cue sheet data embedded in the FLAC source is not preserved in the OGG output. Since this conversion involves full decode and re-encode, processing time scales with file duration and is notably longer than a simple container remux.