SPX to M4R Converter
Processing entirely on your device — large files may take a moment.
Speex Voice Audio and iPhone Ringtone exist for different jobs: SPX is Speex voice audio in an Ogg container — the codec of old VoIP recorders and Asterisk phone systems. Converting MP3 to M4R is how you turn any song into a proper iPhone ringtone that syncs via Finder or iTunes.
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 M4R
| SPX | M4R | |
|---|---|---|
| Compression | Lossy Speex (Ogg) | Lossy AAC |
| Quality | Narrowband/wideband speech | Same as M4A |
| Compatibility | Legacy VoIP stacks | iPhone only |
| Best for | Call recordings, phone systems | iPhone ringtones |
How to convert SPX to M4R
- 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 M4R". The conversion runs entirely inside your browser using WebAssembly — no upload, no queue, no waiting.
- 3
Download results
Download each converted M4R 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 M4R format
M4R is simply iPhone ringtone packaging: an AAC audio file (same as M4A) capped at 40 seconds, named .m4r so iOS treats it as a ringtone instead of a song. GarageBand and Finder sync are the supported paths to install one; the audio itself is ordinary AAC.
Practical workflow: pick the 30–40 second chorus you want, convert to M4R, sync it to the phone, and set it in Sounds & Haptics. Nothing about the audio changes — the extension and the length limit are the entire format.
+ Strengths
- ✓The native iPhone ringtone format
- ✓Simple — it is AAC with a new name
! Limitations
- −Hard 40-second length cap
- −Installation requires sync or GarageBand
Why convert SPX to M4R?
Converting makes sense where the strengths of M4R meet what SPX cannot give you. The native iPhone ringtone format 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 M4R 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 M4R?
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.
Can I convert a whole folder of SPX files?
You can select many files at once and they are processed in a single batch. Output files land in one ZIP download when there is more than one result.
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.