SPX vs W64
A detailed comparison of Speex Audio and Sony Wave64 — file size, quality, compatibility, and which format to choose for your workflow.
Speex Audio
Audio FilesSpeex is an open-source audio compression format specifically designed for speech encoding. It uses Code-Excited Linear Prediction (CELP) and supports narrowband, wideband, and ultra-wideband modes for different speech quality requirements.
About SPX filesSony Wave64
Audio FilesWave64 (W64) is an extension of the WAV format developed by Sony that breaks the 4 GB file size limit of standard WAV by using 64-bit chunk sizes. It is used in professional audio production for very long or multi-channel recordings.
About W64 filesStrengths Comparison
SPX Strengths
- Patent-free voice codec.
- Three sample-rate modes for voice.
- Low CPU decode.
W64 Strengths
- Unlimited file size (64-bit chunks).
- Professional DAW compatibility.
- Bit-exact lossless.
Limitations
SPX Limitations
- Deprecated in favor of Opus.
- No music support.
- Rarely used in new projects.
W64 Limitations
- Less universal than WAV.
- Niche — only matters for very large sessions.
- Competes with RF64.
Technical Specifications
| Specification | SPX | W64 |
|---|---|---|
| MIME type | audio/speex | audio/x-w64 |
| Extension | .spx | .w64 |
| Container | Ogg | — |
| Modes | Narrowband/Wideband/Ultra-wideband | — |
| Successor | Opus | — |
| Max size | — | 2^64 bytes |
| Relative | — | RF64 (EBU 64-bit WAV) |
Typical File Sizes
SPX
- 1 min voice (wideband 24 kbps) ~180 KB
W64
- 1-hour 24-bit 48 kHz mono ~620 MB
- 48-hour field recording ~30 GB
Ready to convert?
Convert between SPX and W64 online, free, and without installing anything. Encrypted upload, automatic deletion after 2 hours.
Frequently Asked Questions
SPX (Speex Audio) is an audio file format used to store sound recordings — music, voice, podcasts, sound effects. The format defines how the audio samples are compressed (or stored raw), what bitrates are supported, and how metadata such as title, artist, album, and cover art is embedded. It is part of the audio files family.
W64 (Sony Wave64) is an audio file format used to store sound recordings — music, voice, podcasts, sound effects. The format defines how the audio samples are compressed (or stored raw), what bitrates are supported, and how metadata such as title, artist, album, and cover art is embedded. It is part of the audio files family.
VLC, foobar2000, and the default media players on Windows and macOS handle SPX natively. On mobile, iOS Music and Android media apps vary in their support — popular formats work everywhere; niche ones may need a dedicated app. If playback fails on a device, converting to MP3 or AAC usually solves it.
VLC, foobar2000, and the default media players on Windows and macOS handle W64 natively. On mobile, iOS Music and Android media apps vary in their support — popular formats work everywhere; niche ones may need a dedicated app. If playback fails on a device, converting to MP3 or AAC usually solves it.
Upload the SPX to KaijuConverter and pick MP3, WAV, FLAC, AAC, OGG, or any other target. Our FFmpeg pipeline decodes the audio and re-encodes to the target format at sensible default bitrates (VBR ~190 kbps for music, 96 kbps for speech). Metadata and cover art travel with the audio where both formats support them.
SPX can be lossy or lossless depending on the specific variant. Lossy variants (smaller files) discard some audio detail during compression in ways tuned to be inaudible; lossless variants preserve every sample exactly but produce larger files. For distribution, lossy at high bitrate is standard; for archival, lossless wins.