MP3 vs SPX
A detailed comparison of MP3 Audio and Speex Audio — file size, quality, compatibility, and which format to choose for your workflow.
MP3 Audio
Audio FilesMP3 is the most widely recognized audio format in the world. It uses lossy compression to dramatically reduce file sizes while maintaining good perceived audio quality, making it the standard for music distribution.
About MP3 filesSpeex 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 filesStrengths Comparison
MP3 Strengths
- Universal support — every device, every player, every car stereo.
- Small file sizes with acceptable quality at 128–320 kbps.
- Completely royalty-free since April 2017.
- ID3 metadata tags support artist, album, cover art, lyrics, and more.
- Efficient decoding — runs on the most basic hardware.
SPX Strengths
- Patent-free voice codec.
- Three sample-rate modes for voice.
- Low CPU decode.
Limitations
MP3 Limitations
- Lossy — re-encoding compounds quality loss.
- Outperformed by AAC, Opus, and OGG at equivalent bitrates.
- Pre-echo artifacts on sharp percussive sounds.
- No native support for multichannel audio (only stereo).
- Bitrate capped at 320 kbps.
SPX Limitations
- Deprecated in favor of Opus.
- No music support.
- Rarely used in new projects.
Technical Specifications
| Specification | MP3 | SPX |
|---|---|---|
| MIME type | audio/mpeg | audio/speex |
| Compression | Lossy — perceptual coding based on psychoacoustic model | — |
| Sample rates | 8, 11.025, 12, 16, 22.05, 24, 32, 44.1, 48 kHz | — |
| Bitrates | 32–320 kbps (CBR) or VBR | — |
| Channels | Mono or stereo only | — |
| Metadata | ID3v1, ID3v2 | — |
| Extension | — | .spx |
| Container | — | Ogg |
| Modes | — | Narrowband/Wideband/Ultra-wideband |
| Successor | — | Opus |
Typical File Sizes
MP3
- Song at 128 kbps (4 min) 3.8 MB
- Song at 320 kbps (4 min) 9.5 MB
- Podcast (1 hour, 96 kbps) 42 MB
- Audiobook (8 hours, 64 kbps) 220 MB
SPX
- 1 min voice (wideband 24 kbps) ~180 KB
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Frequently Asked Questions
MP3 (MPEG Audio Layer III) is the most popular audio format, developed by the Fraunhofer Institute in the early 1990s. It uses lossy compression to dramatically reduce audio file sizes while maintaining acceptable quality for most listeners.
MP3 (MPEG Audio Layer III) is the most popular audio formato, developed pelo Fraunhofer Institute no early 1990s. It uses com perdas compressão to dramatically reduce audio tamanho do arquivos while maintaining acceptable quality para most listeners.
MP3 is universally supported by every music player, smartphone, car stereo, web browser, and operating system. Popular players include Spotify, iTunes, VLC, and Windows Media Player.
MP3 is universally suportado por every music player, smartphone, car stereo, web browser, e operating system. Popular players include Spotify, iTunes, VLC, e Windows Media Player.
Use MP3 when file size and compatibility matter most, such as streaming and portable devices. Use FLAC for lossless archiving of music where you want to preserve the original studio quality without any compression artifacts.
Use MP3 when tamanho do arquivo e compatibilidade matter most, como streaming e portable devices. usar FLAC para sem perdas archiving of music where you querer preserve the original studio quality sem any compressão artifacts.