FLAC to WEBA Converter

Convert FLAC to WEBA: What This Tutorial Covers

.weba is the audio-only form of WebM — the same Matroska-derived container browsers use for video, carrying an Opus stream and nothing else. It is what you want when audio has to be served by a web page, embedded in an HTML5 <audio> element, or shipped inside a web app, and you would rather not hand visitors a multi-megabyte lossless file. This walk-through covers picking a bitrate that is actually appropriate for Opus, the sample-rate change that surprises people, and the one browser that still needs checking.

FLAC is lossless and Opus is not, so this is a one-way step. Keep the FLAC as your master.

How to Convert FLAC to WEBA

1. Upload Your FLAC File: Drag and drop your .flac files onto the page or click "+ Add Files". Several files can be queued and converted in one pass with the same settings.
2. Pick Constant Bitrate, Custom Bitrate, Specific file size, or Quality Preset: Under File Compression, Constant Bitrate is the predictable option — the dropdown runs 8 kbps to 384 kbps and 96–128 kbps is the right neighbourhood for stereo music. Custom Bitrate takes a typed value, Specific file size works the rate out from a target size and the duration, and Quality Preset picks a target for you.
3. Set Audio Channel, Audio Sample Rate and Trim: Leave Audio Channel on "ORIGINAL" for stereo music, or choose MONO for voice to halve the data. Audio Sample Rate can stay on "ORIGINAL" — see the walk-through below for what Opus does with it. Trim exports a single start time and duration.
4. Convert and Download: Click Convert and download the .weba. Files are uploaded over an encrypted connection, converted on our servers, and deleted automatically a few hours later — no sign-up, no watermark.

Walk-through: Choosing a Bitrate for Opus

Opus is unusually efficient, so the bitrates people carry over from MP3 habits are far too high. RFC 6716, the IETF specification that defines the codec, notes that fullband stereo music is best served around 64–128 kbit/s at the default 20 ms frame size — not the 256 or 320 kbps you might use for MP3. Setting a much higher number mostly buys file size.

There is no Audio Codec control on this page because .weba output is always Opus; the setting that matters is the bitrate. When you set one, Opus treats it as an average target rather than a hard ceiling, so the finished file lands close to but not exactly on the arithmetic.

In our testing a 60-second 44.1 kHz stereo FLAC of 4,772,184 bytes encoded to 915,167 bytes at a 128 kbps target — 5.2× smaller, and slightly under the 960,000 bytes plain arithmetic would predict, because the encoder spends fewer bits on quiet passages.

Common Errors and How to Fix Them

• "My 44.1 kHz FLAC came out at 48 kHz" — That is correct behaviour. Opus only operates at 8, 12, 16, 24 and 48 kHz, per RFC 6716; there is no 44.1 kHz mode, so CD-rate material is resampled to 48 kHz on the way in. Every Opus encoder does this, and it is inaudible.
• "The file will not play in Safari" — Check the table below. Apple's Opus support was limited to the CAF container for years and only became full in iOS Safari 18.4. Serve an AAC fallback, or convert to FLAC to M4A if the audience is Apple-heavy.
• "My browser downloads the file instead of playing it" — Your web server is not sending a MIME type it recognises. .weba should be served as audio/webm; a default application/octet-stream makes the browser save it.
• "The file sounds fine but is bigger than expected" — A high Quality Preset can request a bitrate far above what Opus needs, since the preset scale reaches up towards the codec's 510 kbps ceiling. Set the number yourself under Constant Bitrate for web delivery.
• "An old editor or player will not open the .weba" — Desktop audio tools often recognise WebM video but not the audio-only extension. Renaming the file to .webm usually solves it, because the container is the same; otherwise pick an Ogg or MP3 target instead.

Where WEBA Plays

Opus support in the <audio> element, per caniuse:

When This Doesn't Work

If the file is going anywhere other than a browser, .weba is probably the wrong wrapper. Hardware players, car head units and DAWs generally do not know the extension even when they can decode Opus. For those, FLAC to OPUS gives you the same audio in a plain .opus file and FLAC to MP3 trades efficiency for the widest device support that exists. And if the audio has to stay lossless, no lossy codec is the answer at all — keep the FLAC and let the destination deal with it.

Frequently Asked Questions

What exactly is a .weba file?

It is a WebM container holding only an audio track. WebM is a profile of Matroska that Google defined for the web, and the .weba extension signals to servers and tooling that there is no video inside. The audio itself is Opus, defined in IETF RFC 6716 (September 2012), which supports bitrates from 6 kbit/s to 510 kbit/s and sample rates of 8, 12, 16, 24 and 48 kHz. Because it is the same container as WebM video, renaming .weba to .webm produces a perfectly valid file.

Can I choose Vorbis instead of Opus in the WEBA?

Not on this page. The WebM specification allows either Opus or Vorbis, but .weba output here is always encoded as Opus and there is no Audio Codec control to change it. That is a sensible fixed choice: Opus outperforms Vorbis at effectively every bitrate and is the codec browsers optimise for. If you specifically need a Vorbis stream for an older toolchain, FLAC to OGG produces Vorbis in an Ogg container.

Will I lose quality converting FLAC to WEBA?

Yes — this is a lossless-to-lossy transcode and the discarded data cannot be recovered later. In practice the loss is small: Opus at 96–128 kbps stereo is hard to distinguish from the source on ordinary playback gear, which is why RFC 6716 points at that range for fullband stereo music. Treat the WEBA as a delivery copy and keep the FLAC.

Why does the sample rate change to 48 kHz?

Because Opus has no 44.1 kHz mode. The codec is defined for 8, 12, 16, 24 and 48 kHz operation, so a CD-rate FLAC is resampled to 48 kHz during encoding — this happens in every Opus encoder, not just ours, and a high-quality resample at that ratio is inaudible. If preserving 44.1 kHz exactly is a requirement, you need a different codec entirely.

Do my tags survive into the WEBA?

Text tags do. Title, artist and album from the FLAC's Vorbis comments are written into the container's Matroska tag elements, so players that read WebM metadata will show them. Embedded cover art does not survive, because the audio pipeline exports the audio stream only. Browsers do not display audio tags anyway, so for web use this rarely matters.

How much smaller will the file be?

Five to ten times smaller for typical music. FLAC needs roughly 500–1,100 kbps for CD-quality stereo depending on the material, while Opus at 96–128 kbps carries the same track. Speech compresses far harder still: mono voice at 32 kbps is around 0.24 MB per minute, so an hour-long interview fits in about 14 MB.

Is WEBA better than MP3 for a website?

For quality per byte, comfortably. Opus beats MP3 at every bitrate and is dramatically better below 64 kbps, so a 96 kbps WEBA typically sounds better than a 160 kbps MP3 while being smaller. The trade is compatibility: MP3 plays literally everywhere, including in Safari without caveats and on hardware from twenty years ago. A common pattern is to serve WEBA as the primary source with an MP3 or M4A fallback in the same <audio> element.

What happens to my files after conversion?

They are uploaded over an encrypted connection, converted on our servers, and both the upload and the result are deleted automatically a few hours later. Nothing is shared or made public and no account is required. Going the other way, WEBA to FLAC will wrap the audio losslessly again, but it cannot restore anything Opus discarded — that path only makes sense if a tool you use insists on FLAC input.