SPX vs WAV
A detailed comparison of Speex Audio and WAV Audio — 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 filesWAV Audio
Audio FilesWAV is an uncompressed audio format that preserves full audio fidelity. Files are large but provide lossless, CD-quality sound. It is the standard working format in audio production and editing.
About WAV filesStrengths Comparison
SPX Strengths
- Patent-free voice codec.
- Three sample-rate modes for voice.
- Low CPU decode.
WAV Strengths
- Bit-perfect, uncompressed audio — the professional studio standard.
- Universally supported for playback, editing, and analysis.
- No re-encoding penalty — edit and save repeatedly with zero quality loss.
- Simple internal structure — easy to parse programmatically.
- Supports up to 32-bit float and 384 kHz sample rates.
Limitations
SPX Limitations
- Deprecated in favor of Opus.
- No music support.
- Rarely used in new projects.
WAV Limitations
- Enormous file sizes — 10 MB per minute for CD-quality stereo.
- 4 GB size limit for standard WAV (RF64/W64 variants extend it but break compatibility).
- No native support for cover art or rich metadata.
- Impractical for casual listening or bandwidth-constrained delivery.
Technical Specifications
| Specification | SPX | WAV |
|---|---|---|
| MIME type | audio/speex | audio/wav |
| Extension | .spx | — |
| Container | Ogg | RIFF |
| Modes | Narrowband/Wideband/Ultra-wideband | — |
| Successor | Opus | — |
| Typical codec | — | PCM (uncompressed) |
| Bit depth | — | 8, 16, 24, 32 bit integer or float |
| Sample rate | — | Up to 384 kHz |
| Max size | — | 4 GB (standard WAV), unlimited (RF64 / W64) |
Typical File Sizes
SPX
- 1 min voice (wideband 24 kbps) ~180 KB
WAV
- Song (4 min, CD quality) 40 MB
- Voice memo (1 min, 16-bit 44.1 kHz) 10 MB
- Studio master (1 min, 24-bit 96 kHz) 33 MB
- Field recording (1 hour, 24-bit 48 kHz) 1 GB
Ready to convert?
Convert between SPX and WAV 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.
WAV (Waveform Audio File Format) is an uncompressed audio format co-developed by Microsoft and IBM in 1991. It stores raw PCM audio data, providing studio-quality sound at the cost of large file sizes.
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.
WAV files play on virtually every media player and operating system including VLC, Windows Media Player, iTunes, Audacity, and all DAWs (Digital Audio Workstations) like Pro Tools and Logic Pro.
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.