SPX to FLAC Converter
Processing entirely on your device — large files may take a moment.
Convert to FLAC when you want a permanent, lossless archive of your music. If your files are still in SPX format, this page is the shortcut: SPX is Speex voice audio in an Ogg container — the codec of old VoIP recorders and Asterisk phone systems.
This converter runs entirely in your browser using WebAssembly — your files never leave your device, nothing is uploaded, and there are no watermarks, sign-ups or queues. Drop in several files at once to convert them as a batch.
How SPX compares to FLAC
| SPX | FLAC | |
|---|---|---|
| Compression | Lossy Speex (Ogg) | Lossless (~50–60% of PCM) |
| Quality | Narrowband/wideband speech | Bit-perfect |
| Compatibility | Legacy VoIP stacks | Players, Android, hi-res rigs |
| Best for | Call recordings, phone systems | Music collections and archival |
How to convert SPX to FLAC
- 1
Select your files
Drag & drop your SPX files onto the area above, or click to browse. You can add multiple files at once for batch conversion.
- 2
Convert instantly
Click "Convert to FLAC". The conversion runs entirely inside your browser using WebAssembly — no upload, no queue, no waiting.
- 3
Download results
Download each converted FLAC file individually, or grab everything at once as a ZIP archive.
About the SPX format
SPX is Speex speech audio in an Ogg container — the open voice codec of the 2000s VoIP wave, tuned for telephone-band speech at absurdly low bitrates. Asterisk PBX call recordings and old conferencing archives are where you meet it.
Speex was formally retired in favor of Opus, and players have followed. Converting SPX to MP3 (or Opus for the adventurous) rescues call archives before they become unplayable.
+ Strengths
- ✓Extremely compact for speech
- ✓Open-source lineage
! Limitations
- −Speech-only: music is unusable
- −Format officially retired
About the FLAC format
FLAC (Free Lossless Audio Codec, Xiph, 2001) compresses audio to roughly 50–60% of its PCM size and restores every bit on playback — a ZIP for music that also carries proper tags, hi-res support up to 32-bit/655 kHz on paper (24-bit/192 kHz in practice) and full open-source pedigree. It is the archive format of digital music collections.
Support followed maturity: every serious player, modern Android (system-level), most cars and streaming purists' devices handle FLAC natively. Apple resisted for years but iOS 11+ plays it, with the caveat that iTunes/Apple Music syncing still prefers ALAC. The price of losslessness is size — about five times MP3 at comparable quality.
+ Strengths
- ✓Bit-perfect lossless with real compression
- ✓Hi-res capable (24-bit/192 kHz)
- ✓Open, unpatented, tag-native
! Limitations
- −~5× the size of lossy formats
- −Apple syncing prefers ALAC
- −Overkill for casual listening
Why convert SPX to FLAC?
Converting makes sense where the strengths of FLAC meet what SPX cannot give you. Bit-perfect lossless with real compression Meanwhile Speech-only: music is unusable One pass through the converter above puts your file on the right side of that trade-off.
Frequently asked questions
Is this SPX to FLAC converter really free?
Yes — completely free, with no sign-up, no watermark and no daily conversion limits. The site is supported by advertising.
Are my files uploaded to a server?
No. The conversion runs entirely inside your browser using WebAssembly, so your files never leave your device — that is what makes it instant and private.
Does it work on Windows, Mac, iPhone and Android?
Yes. Anything with a modern browser works: Windows, macOS, Linux, Android and iOS. No software installation is required.
Is there a file size limit for SPX to FLAC?
The only limit is your device's memory, since nothing is uploaded. Files up to a few hundred megabytes work fine on a modern desktop browser; very large files simply take a little longer.
Will converting SPX to FLAC reduce audio quality?
If FLAC is lossless, the output contains everything the SPX file contains — no further loss is added. If FLAC is lossy, one recompression pass is unavoidable; the quality slider controls how much. Loss that already happened in the source file can never be undone by converting.
Are tags like title and artist preserved?
Tag handling varies between target formats and this conversion focuses on the audio itself. For archival copies where tags matter, keep the original file; the converted copy is for playback and sharing.