DFF vs SPX
A detailed comparison of DSD Interchange File and Speex Audio — file size, quality, compatibility, and which format to choose for your workflow.
DSD Interchange File
Audio FilesDFF (DSDIFF - DSD Interchange File Format) is the original file format for DSD audio data, developed by Philips. Unlike DSF, it uses a chunked IFF structure and is the native format for many professional DSD recording systems.
About DFF 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
DFF Strengths
- SACD-native format.
- Supported by high-end DACs.
- Bit-exact DSD preservation.
SPX Strengths
- Patent-free voice codec.
- Three sample-rate modes for voice.
- Low CPU decode.
Limitations
DFF Limitations
- No metadata support.
- Huge files (2-6 GB album).
- Niche audiophile market.
- Specialized decoder hardware needed.
SPX Limitations
- Deprecated in favor of Opus.
- No music support.
- Rarely used in new projects.
Technical Specifications
| Specification | DFF | SPX |
|---|---|---|
| MIME type | audio/x-dff | audio/speex |
| Extension | .dff | .spx |
| Sample rate | 2.8224 MHz (DSD64), 5.6448 (DSD128) | — |
| Creator | Philips | — |
| Sibling | .dsf | — |
| Container | — | Ogg |
| Modes | — | Narrowband/Wideband/Ultra-wideband |
| Successor | — | Opus |
Typical File Sizes
DFF
- Full SACD album (DSD64) 2-4 GB
- DSD128 album 4-8 GB
SPX
- 1 min voice (wideband 24 kbps) ~180 KB
Ready to convert?
Convert between DFF and SPX online, free, and without installing anything. Encrypted upload, automatic deletion after 2 hours.
Frequently Asked Questions
DFF (DSD Interchange File) 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.
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.
VLC, foobar2000, and the default media players on Windows and macOS handle DFF 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 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.
Upload the DFF 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.
DFF 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.