Convert FLAC to WEBA — Free Online Tool
Convert FLAC lossless audio to WEBA format using the Opus codec, producing compact, web-optimized audio files ideal for browser playback and streaming. This conversion re-encodes the lossless FLAC audio into lossy Opus at 128k bitrate, balancing excellent sound quality with dramatically smaller file sizes.
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FFmpeg Command
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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 from the original recording is preserved exactly. During conversion, FFmpeg decodes the FLAC audio to raw PCM, then re-encodes it using the libopus encoder into a WebM-based WEBA container. Opus is a modern lossy codec that uses perceptual encoding to discard audio information the human ear is unlikely to notice, achieving much smaller file sizes than FLAC. Because WEBA is an audio-only container (a WebM file with only an audio track), the -vn flag ensures no spurious video stream is written. The result is a single Opus audio stream inside a WebM container with the .weba extension, which browsers like Chrome and Firefox can play natively without any plugin.
What Each Flag Does
| Flag | What it does |
|---|---|
ffmpeg
|
Invokes the FFmpeg media processing tool, which handles the decoding of the FLAC input and re-encoding to Opus/WEBA output entirely within your browser via FFmpeg.wasm. |
-i input.flac
|
Specifies the input FLAC file. FFmpeg reads and fully decodes the lossless FLAC audio stream to raw PCM before passing it to the Opus encoder. |
-c:a libopus
|
Selects the libopus encoder for the audio stream, which produces an Opus-encoded audio track — the standard and preferred codec for WEBA containers, offering excellent quality at low bitrates compared to older codecs like Vorbis. |
-b:a 128k
|
Sets the Opus audio bitrate to 128 kilobits per second, which delivers transparent or near-transparent quality for most music and voice content from a lossless FLAC source while keeping the output file roughly 6–8 times smaller than the original. |
-vn
|
Explicitly disables any video output stream, ensuring the WEBA file contains only the Opus audio track. This guards against any edge case where FFmpeg might attempt to write an empty or null video stream into the WebM container. |
output.weba
|
Defines the output file with the .weba extension, which tells FFmpeg to write a WebM container (audio-only variant) and signals to browsers and media players that the file contains audio without a video track. |
Common Use Cases
- Preparing a high-quality FLAC music archive for a web-based music player or streaming app where bandwidth efficiency matters more than bit-perfect reproduction
- Converting a FLAC podcast master recording to WEBA/Opus for delivery through a web application, taking advantage of Opus's low-latency design for real-time-style playback
- Reducing the file size of large FLAC audiobook files before embedding them in a Progressive Web App (PWA) or web-based e-reader that supports native WebM audio
- Transcoding FLAC stems or samples for use in a browser-based digital audio workstation (DAW) or web audio production tool that only accepts Opus/WebM input
- Creating web-deliverable versions of lossless FLAC sound effects or game audio assets for an HTML5 game where fast loading and broad Chromium-based browser support are priorities
- Archiving space-saving Opus copies of a large FLAC collection specifically for offline playback in Chromebook or Android environments where Opus/WebM has first-class support
Frequently Asked Questions
At the default 128k bitrate, Opus delivers audio quality that most listeners find indistinguishable from lossless in casual listening, especially for music, speech, and podcasts. However, because Opus is a lossy codec, the conversion is irreversible — once you discard the audio data that Opus omits, you cannot recover it. If you need to preserve the original lossless quality, always keep your source FLAC files and only distribute the WEBA version.
The reduction is substantial. A FLAC file encoded at compression level 5 might average 700–1000 kbps for CD-quality stereo audio, while the Opus output at 128k is roughly 6–8 times smaller. For a 60-minute album, this could mean shrinking from around 400–500 MB (FLAC) down to roughly 55–70 MB (WEBA/Opus 128k), making it far more practical for web delivery and streaming.
Basic metadata tags such as title, artist, album, and track number are carried over by FFmpeg into the Opus stream inside the WebM container. However, FLAC-specific metadata features like cue sheets and ReplayGain tags may not map cleanly to the WEBA/Opus container, and not all media players read WebM Opus tags equally well. It is worth verifying your tags with a tool like MediaInfo or a browser console after conversion.
Both .weba and .webm are WebM containers at the binary level — the difference is purely a naming convention. The .weba extension signals that the file contains audio only (no video), which helps browsers and media players identify and handle it correctly as an audio file. Some servers and platforms may require the correct MIME type (audio/webm) to be set, especially if you are serving WEBA files for web playback.
Chrome, Firefox, Edge, and Opera support Opus in WebM containers natively, as do Android devices and Chromebooks. Safari added WebM/Opus support in Safari 16 (macOS Ventura and iOS 16), so coverage is now broad. Notably, older Apple devices and some embedded or automotive audio systems may still lack support, in which case FLAC or AAC in an MP4 container would be a safer choice for universal compatibility.
Replace the 128k value in the -b:a 128k flag with your preferred bitrate. For near-transparent quality from a FLAC source, 192k or 256k Opus is excellent and still far smaller than the original FLAC. For voice-only content like podcasts or audiobooks, 64k or 96k is usually sufficient and produces very small files. For example: ffmpeg -i input.flac -c:a libopus -b:a 192k -vn output.weba
Technical Notes
FLAC to WEBA is a lossy transcoding operation — the audio must be fully decoded from its lossless representation and re-encoded with Opus's perceptual model, so this is not a simple remux. The Opus codec (RFC 6716) is particularly well-suited for this source material because it performs exceptionally across a wide range of content types, from music to speech, and it natively supports sample rates up to 48 kHz. FFmpeg will resample FLAC files recorded at 44.1 kHz (CD standard) or other rates to 48 kHz for Opus encoding, which is standard behavior and does not audibly degrade quality. Bit depths above 16-bit (e.g., 24-bit FLAC masters) are also downsampled during encoding, as Opus targets perceptual fidelity rather than bit-perfect reproduction. FLAC's replay gain and cue sheet metadata have no direct equivalents in the WebM container specification, so those fields will be silently dropped. The -vn flag is included as a safeguard to prevent any unexpected or empty video stream from being written to the output — while FLAC itself carries no video, it is good practice to explicitly suppress video output when targeting an audio-only container like WEBA.