Audio Converter

Get the Best Possible Opus from Your Lossless FLAC Master

Upload your FLAC file and get an Opus file ready for Discord bots, WebRTC pipelines, HTML5 web audio, and mobile streaming — encoded directly from a lossless source so the Opus encoder receives a perfect, uncompressed signal with no prior quality ceiling.

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Get the Best Possible Opus from Your Lossless FLAC Master

Free Tool

Audio Format Converter

Upload any audio file, choose an output format, and download the converted result. Supports MP3, WAV, FLAC, AAC, OGG, ALAC, WMA, Opus and M4A.

Drop your audio file here

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Serve the Best Possible Opus for HTML5 Web Audio from a Lossless Master

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Serve the Best Possible Opus for HTML5 Web Audio from a Lossless Master

Web developers who maintain FLAC masters for music, sound effects, and UI audio can convert to Opus for HTML5 delivery. Chrome, Firefox, and Edge all support Opus natively in the Web Audio API and the <audio> element. Encoding from FLAC gives the Opus encoder a perfect, uncompressed signal — a first-generation encode that outperforms any Opus converted from a prior MP3 or AAC.

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Developer at a laptop building a Discord bot with a code editor open

Prepare Opus Audio Assets for Discord Bots from Lossless Sources

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Prepare Opus Audio Assets for Discord Bots from Lossless Sources

Discord bots that play music or sound effects in voice channels deliver audio as Opus streams via the Discord Voice API. Serving Opus audio that was first encoded from a FLAC master means each listener receives the best Opus quality the codec can produce at the target bitrate. Converting from a prior MP3 or AAC produces a secondary encode with a quality ceiling already imposed by the original lossy compression.

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Person streaming music on a phone with a clean mobile player interface

Distribute Bandwidth-Efficient Opus from Your Lossless Archive

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Distribute Bandwidth-Efficient Opus from Your Lossless Archive

Mobile apps, self-hosted streaming servers, and bandwidth-limited delivery pipelines benefit significantly from Opus over MP3, AAC, or OGG Vorbis at the same bitrate. Opus at 96 kbps matches MP3 at 128 kbps perceptually. Encoding from a FLAC master ensures every byte of Opus quality is spent on the audio signal — not compensating for degradation introduced by a prior lossy encode.

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How It Works

Three steps to the best Opus from a lossless source

Upload your FLAC file

Drop your FLAC file onto the tool or click to browse. CD rips, studio masters, DAW exports, and archival recordings are all accepted.

Convert to Opus

Click "Convert". FFmpeg decodes the FLAC losslessly to PCM and encodes it as Opus — one clean encoding pass from a perfect, uncompressed source.

Download your Opus file

Download your .opus file ready for Discord bots, web audio pipelines, mobile streaming apps, or any other Opus-compatible delivery target.

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Deep Dive

FLAC to Opus: Lossless Archive to High-Efficiency Streaming Codec

FLAC is the lossless master. Opus is the modern open codec for streaming, web audio, and voice. Converting from FLAC ensures the Opus you produce is the best the codec can create at any bitrate.

Web developers, streamers, Discord bot builders, and mobile app developers converting FLAC to Opus

FLAC: The Perfect Archive, Optimized for Storage

FLAC (Free Lossless Audio Codec) stores audio with no quality loss — decoding always produces bit-for-bit identical PCM. It is the audiophile standard for archiving, DAW work, and collection management. However, FLAC files are large (25 to 35 MB per track) and are not the delivery format expected by Discord bots, WebRTC pipelines, mobile apps, or bandwidth-sensitive streaming infrastructure.

TypeLossless compression, open-source

Typical size4-minute stereo track: ~25 to 35 MB

Discord bot supportNot a native streaming format for Discord Voice API

Always keep the FLAC as the archive master. Opus is the derivative for delivery and streaming.

Opus: The Best Open Codec for Streaming, Voice, and Web

Opus (IETF RFC 6716) is an open, patent-free codec engineered for low-latency, high-quality audio at low bitrates. It outperforms MP3, AAC, and OGG Vorbis at equivalent bitrates. Opus is the native codec for Discord voice, WebRTC, and the Web Audio API. It is supported natively in Chrome, Firefox, and Edge, and plays in VLC, mpv, and every modern media player.

TypeLossy, open-source (Xiph.Org / IETF RFC 6716)

Typical size4-minute stereo at 128 kbps: ~3.8 MB (vs ~30 MB for FLAC)

Browser supportChrome, Firefox, Edge, Opera natively

Opus at 96 kbps is perceptually comparable to MP3 at 128 kbps, and Opus at 128 kbps is widely considered transparent for music.

Why FLAC Is the Best Source for Opus Encoding

The quality of any Opus file depends on the signal fed to the encoder. A FLAC source provides perfect, uncompressed PCM — the full original audio. The Opus encoder working from FLAC produces the best result at any bitrate with no prior quality ceiling. Encoding Opus from an existing MP3 or AAC passes already-degraded audio through a second lossy encoder, compounding the quality loss.

FLAC -> OpusOne encoding pass from perfect PCM: best achievable quality

MP3 -> OpusSecond lossy pass: quality ceiling set by prior MP3 encoding

AAC -> OpusSecond lossy pass: compounding degradation from both codecs

Always encode delivery formats from lossless masters whenever possible.

When Opus Is the Right Destination from FLAC

Opus is the right destination when the audio will be delivered over a network where bandwidth efficiency matters, served via HTML5 web audio on Chrome or Firefox, used in a Discord bot or WebRTC application, or streamed on a self-hosted server like Navidrome or Jellyfin. For maximum device compatibility including car stereos and legacy hardware, MP3 still has broader reach. For Apple platforms, AAC in M4A is the standard.

Use Opus forDiscord bots, WebRTC, HTML5 Chrome/Firefox/Edge, self-hosted streaming, mobile apps

Use MP3 forCar stereos, universal device sharing, legacy players, podcast platforms

Use AAC/M4A foriPhone, Apple Music, Apple Podcasts, Safari

Our converter uses FFmpeg to decode FLAC losslessly and encode as Opus, extracting the best quality the codec can deliver from a perfect source.

Benefits

Why Convert FLAC to Opus

🎯

Best Possible Opus Quality

Encoding from a lossless FLAC source means the Opus encoder receives a perfect signal — no quality ceiling from any prior lossy codec.

📶

Smaller Files Than MP3 at Equal Quality

Opus at 96 kbps matches MP3 at 128 kbps perceptually. Delivering the same quality with 25% less bandwidth is a meaningful advantage for streaming and mobile.

🌐

Native in Browsers and Discord

Chrome, Firefox, and Edge support Opus in HTML5 audio and the Web Audio API natively. Discord Voice streams Opus. No plugin required.

⚡

Fast Conversion

Most FLAC files convert to Opus in under 30 seconds on dedicated FFmpeg servers.

Who Uses It

Who Converts FLAC to Opus

Web developers serving audio assets, Discord bot builders, mobile app developers, self-hosted streaming server operators, and musicians who need a bandwidth-efficient delivery format from their lossless masters.

Web developers, Discord bot builders, mobile app developers, and streaming server operators

Web Developers Serving Opus via HTML5 Audio

Web developers who maintain FLAC masters for music, ambient audio, or sound effects can convert to Opus for delivery via the HTML5 <audio> element or the Web Audio API. Chrome, Firefox, and Edge all support Opus natively. Encoding from the FLAC master ensures the delivered Opus is a first-generation encode with no prior lossy degradation.

Browser supportChrome, Firefox, Edge, Opera natively; Safari requires a fallback

Discord Bot Developers Serving Audio in Voice Channels

Discord bots built with discord.js, discord.py, or equivalent libraries deliver audio to voice channels as Opus streams. Bot developers who maintain FLAC sound libraries can convert to Opus for direct playback. Encoding from FLAC provides the highest quality Opus stream the codec can produce at the target bitrate.

Librariesdiscord.js with @discordjs/voice, discord.py with wavelink or similar

Self-Hosted Streaming Server Operators

Operators of Navidrome, Jellyfin, Airsonic, or Funkwhale servers who maintain FLAC libraries can convert to Opus for transcoded streaming to mobile clients. Opus at 96 to 128 kbps provides transparent quality for mobile listeners at a fraction of the bandwidth that FLAC streaming requires.

Compatible serversNavidrome, Jellyfin, Airsonic, Funkwhale, Ampache

Mobile App Developers Building Audio Features

Mobile app developers building music players, meditation apps, language learning tools, or audio guides need a format that balances quality and download size for users on cellular connections. Opus at 64 to 128 kbps produces excellent quality at file sizes 8 to 10 times smaller than FLAC, with no perceptible quality loss for most listeners.

WebRTC and VoIP Audio Engineers

Opus is the mandatory codec for WebRTC in Chrome, Firefox, and Edge. Developers building browser-based voice or audio communication tools who need to pre-encode or cache audio clips can convert FLAC masters to Opus for use in WebRTC media streams or as injected audio in a pipeline.

SpecificationOpus is mandatory in WebRTC (RFC 7874) for voice and audio

Audiophiles Building a Compressed Library for Mobile Listening

Music enthusiasts who maintain a large FLAC archive but want a lightweight copy for a phone or portable player with limited storage can convert to Opus. A 100 GB FLAC library converts to roughly 10 to 15 GB at 128 kbps Opus with no perceptible quality loss for most tracks.

Space savingOpus at 128 kbps is typically 8 to 10x smaller than FLAC

Converts using FFmpeg on dedicated servers.

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Related Tools

Frequently Asked Questions

Why is converting FLAC to Opus better than converting MP3 to Opus?

Converting an existing MP3 to Opus runs already-compressed audio through a second lossy encoder — Opus receives a degraded signal and can only work within that quality ceiling. Converting FLAC to Opus gives the Opus encoder a perfect, uncompressed PCM signal — the full original recording. The resulting Opus is the best quality the codec can produce at the target bitrate, with no prior lossy degradation.

What bitrate should I use when converting FLAC to Opus?

For music, 128 kbps is widely considered transparent by most listeners. 96 kbps provides excellent quality at a smaller file size and is a strong choice for streaming or mobile delivery. 64 kbps works well for voice, podcasts, and spoken word where file size matters most. Because the source is lossless FLAC, every bitrate will produce the best Opus the codec can deliver at that setting.

Does Opus work in all browsers?

Chrome, Firefox, and Edge support Opus natively in HTML5 audio and the Web Audio API without any plugin. Safari on macOS and iOS does not support Opus in <audio> natively. For web projects requiring full cross-browser support including Safari, serve an MP3 or AAC fallback alongside the Opus, or use a JavaScript decoder such as opus-media-recorder.

Can I use the Opus file directly in a Discord bot?

Yes. Discord voice channels transmit audio as Opus streams. Discord bot libraries including @discordjs/voice (Node.js) and wavelink (Python) can play .opus files directly or use FFmpeg to stream from them. Encoding from a FLAC master gives your bot the best achievable audio quality at any target bitrate.

Is Opus supported on iPhone and Android?

Android supports Opus natively in the MediaPlayer API from Android 5.0 (Lollipop) onward. iOS supports Opus in AVFoundation from iOS 11 onward, though browser-based playback in Safari still requires a fallback. For maximum mobile compatibility, MP3 or AAC in M4A remain safer choices for consumer-facing apps.

Is there a file size limit?

The upload limit is 100 MB per file. Most FLAC audio tracks are well within this limit.

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Upload your lossless master above and get the best possible Opus in seconds.