Convert Free Lossless Audio Codec (.flac) to WebM Video (.webm) online for free. Fast, secure audio conversion with no watermarks or registration.
Upload your .flac file by dragging it into the upload area or clicking to browse.
Choose your output settings. The default settings work great for most files.
Click Convert and download your .webm file when it's ready.
WebM is Google's open media container built for the web, based on Matroska. It supports VP8/VP9 video with Vorbis or Opus audio. Converting FLAC to WebM encodes the audio as Opus (preferred) or Vorbis inside a WebM container. WebM is natively supported by Chrome, Firefox, Edge, and Opera, making it a strong choice for web audio delivery. Opus in WebM is particularly powerful — the Opus codec handles everything from 6 kbps voice to 510 kbps high-fidelity stereo music.
WebM with Opus audio is the most efficient open-format option for web delivery. Opus at 128 kbps matches AAC at 256 kbps in listening tests, making it the most bandwidth-efficient choice for streaming and progressive download. Google's web products (YouTube, Google Drive, Google Meet) all use WebM/Opus internally. For web developers who want patent-free audio without sacrificing quality, WebM is the ideal target.
FFmpeg decodes FLAC to PCM and encodes using libopus inside a WebM (Matroska) container. Opus supports sample rates from 8 to 48 kHz with automatic internal resampling. It handles mono, stereo, and multichannel (up to 255 channels for ambisonics). Opus uses a hybrid approach: SILK (speech) for low frequencies and CELT (music) for high frequencies, switching dynamically based on content. The WebM container provides CRC-protected pages and efficient seeking.
Opus at 128 kbps is transparent for most listeners — it consistently wins blind listening tests against AAC and Vorbis at equivalent bitrates. At 96 kbps, Opus still sounds very good for music. At 64 kbps, it outperforms every competing codec for speech. Since FLAC is lossless, the Opus encoding represents a single generation of highly efficient lossy compression.
| Device | FLAC | WebM |
|---|---|---|
| Windows PC | Partial | Partial |
| macOS | Partial | Partial |
| iPhone/iPad | Partial | Partial |
| Android | Native | Native |
| Linux | Partial | Native |
| Web Browser | No |
Resolution: N/A
Bitrate: 320 kbps
OGG Vorbis preferred
Resolution: N/A
Bitrate: 256 kbps
AAC format required
Resolution: N/A
Bitrate: 128 kbps
Lossless FLAC/WAV for best quality
Resolution: N/A
Bitrate: 128 kbps
MP3 mono for spoken word
FLAC to WebM with Opus audio is the gold standard for efficient, open-format web audio delivery. It combines the best lossy codec (Opus) with the most web-friendly open container (WebM).
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| Native |
| Ominaisuus | FLAC | WebM |
|---|---|---|
| Koko nimi | Free Lossless Audio Codec | WebM Video |
| Tiedostopääte | .flac | .webm |
| Paras käyttökohde | Lossless compression | Web optimized |