AC3 → Opus

Yes, and it is worth planning around. Both formats are lossy, so the Opus encoder is working from audio that has already been through one psychoacoustic pass, and its own decisions compound the first set. At 192 kbps or above the result is still transparent for most listening. If you have a lossless master anywhere, encoding the Opus from that instead avoids the double pass entirely. AC-3 is lossy multichannel audio, normally 5.1 at 384 or 448 kbps, with metadata for dialogue normalisation and downmixing. Opus scales from 6 kbps mono speech to 510 kbps stereo music in the same bitstream and switches modes automatically.

Yes, and it is a genuine gain over AC3, which has nowhere dependable to store any of it. Opus carries title, artist, album, year, track number and embedded cover art in the container itself, so a music library files it correctly without a manual pass. Opus is the best-sounding lossy codec at low bitrates by a clear margin, and it powers WhatsApp voice notes, Discord and WebRTC.

Often not. AC3 is decoded by essentially everything, including car head units and elderly players; Opus needs software that knows the codec, which standalone hardware frequently does not have. If the destination is a car stereo or a portable player, that is a strong argument for staying on AC3. Opus is almost never supported by standalone hardware — assume software playback only, and expect car stereos to ignore it.

If AC3 is lossy and Opus is lossless (e.g. MP3 → WAV), the Opus is no better than the AC3 — you cannot recover information already discarded. If AC3 is lossless and Opus is lossy, the Opus codec recompresses; at 192 kbps the result is transparent for most content.

Several files in one job need a paid plan. Free use is one file per conversion, one conversion an hour. On a paid plan you can add several files to one job, then download each result on its own or all of them in one ZIP.

By default yes — 48 kHz AC3 stays 48 kHz in Opus. If you need to downsample for compatibility (96 kHz → 44.1 kHz for CD burning), the sample-rate option applies high-quality resampling in the same encode pass.

Not in this step. The converter has no loudness setting and leaves the level as it is. To even out the volume, run the finished Opus through a Normalize tool on this site.

MP3 plays almost everywhere. AAC plays on Apple devices, most Android phones and Sonos. FLAC plays on Sonos and Android but not on older iPods, and WAV plays on nearly everything but makes large files. There are no device presets on this page, so choose the target format your player supports.

Yes. Uploaded AC3 files are processed on our own conversion servers, no person reviews them, and they are never shared. The upload and the converted Opus are both deleted automatically about 24 hours after the conversion, which leaves time to download the result. See /privacy/ for the full policy.