SPX vs VOC
A detailed comparison of Speex Audio and Creative Voice — 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 filesCreative Voice
Audio FilesVOC (Creative Voice) is an audio file format created by Creative Labs for Sound Blaster sound cards. It was a dominant PC audio format in the DOS gaming era, supporting multiple data blocks with different sample rates within a single file.
About VOC filesStrengths Comparison
SPX Strengths
- Patent-free voice codec.
- Three sample-rate modes for voice.
- Low CPU decode.
VOC Strengths
- Retro-gaming archive format.
- Supported by DOSBox and SoX.
- Block-based structure allows streaming.
Limitations
SPX Limitations
- Deprecated in favor of Opus.
- No music support.
- Rarely used in new projects.
VOC Limitations
- Legacy — no new content since mid-1990s.
- Limited sample rates (up to 44.1 kHz).
- No metadata.
Technical Specifications
| Specification | SPX | VOC |
|---|---|---|
| MIME type | audio/speex | audio/x-voc |
| Extension | .spx | .voc |
| Container | Ogg | — |
| Modes | Narrowband/Wideband/Ultra-wideband | — |
| Successor | Opus | — |
| Codecs | — | PCM 8/16-bit, ADPCM |
| Hardware origin | — | Sound Blaster Pro (1991) |
Typical File Sizes
SPX
- 1 min voice (wideband 24 kbps) ~180 KB
VOC
- DOS game sound effect 5-50 KB
- Short speech sample 30-300 KB
Ready to convert?
Convert between SPX and VOC 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.
VOC (Creative Voice) 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 VOC 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.