What is the SEQ file format?
A .seq file in the Sony PlayStation format is a binary music sequence used in PS1 (PSX) game development. Created by Sony Computer Entertainment, it drives the PlayStation's SPU (Sound Processing Unit), controlling in-game music playback and audio cues.
The file opens with a four-byte pSEQ magic signature, followed by a version word, PPQ (pulses per quarter note) resolution, an initial tempo expressed in microseconds per beat, and time-signature bytes. Track data is structured closely after MIDI Format 0: variable-length delta-time values interleaved with standard MIDI status bytes. Loop points are encoded via NRPN messages - CC#99 value 20 marks loop start, value 30 marks loop end, and CC#06 sets the repeat count (127 = infinite loop).
A .seq file carries no audio samples; it works in tandem with a companion .vab instrument bank that holds the patches loaded into the SPU. A multi-track variant called .sep uses the pSEP magic and bundles several sequences together.
The format is PS1-specific and was not carried forward to PlayStation 2. It remains widely studied by the game preservation and modding community. The open-source command-line tool seq2mid (loveemu, GitHub) converts .seq files to standard MIDI for playback or editing in modern software.
Security & safety
RISK: LOWBinary audio data or MIDI sequence; no executable code. Safe to handle.
Format details
in a nutshell- PowerTracks Pro Audio Project File - PG Music's PowerTracks Pro Audio uses .seq as its native project format (MIDI + audio + VST instances); unrelated to Sony PS1 SEQ. Still actively maintained as of 2026.
- DNA/Protein Sequence Text File - Some bioinformatics tools (Chromas, DNAbaser) export plain-text DNA sequences as .seq files; simple text format, no standard header.
- Atari / CMS Sequencer formats - Several legacy Atari and early DOS MIDI sequencers used .seq for their proprietary project files; all defunct.
Programs that open SEQ files
Windows4 apps
DuckStation (PS1 emulator)
Open-source Play PS1 games containing .seq audio; not a standalone SEQ player - requires full game context.
seq2mid (command-line tool)
Open-source Convert PS1 SEQ → standard MIDI (.mid); run: seq2mid input.seq output.mid 
Linux1 app
Technical details
deep spec| Magic bytes | pSEQ (hex: 70 53 45 51) at offset 0 |
| Byte order | Little-endian |
| Encoding | Binary |
| Container | Custom Sony binary container |
| Typical file size | 1 KB - 200 KB |
| PPQ resolution | Variable; stored as 2-byte field in header |
| Tempo encoding | Microseconds per beat, stored as 3-byte value in header |
| Loop mechanism | NRPN CC#99 (value 20 = start, 30 = end); CC#06 sets count (127 = infinite) |
| Multi-track variant | .sep format (pSEP magic); bundles multiple sequences |
| Companion file | .vab instrument bank supplying SPU sample patches |
| Platform | Sony PlayStation (PS1/PSX); not used on PS2 |
| MIDI relationship | Structurally similar to SMF Format 0 with PS1-specific NRPN extensions |
| Released | 1994 (Sony PlayStation / PS1) |
| Latest version | SEQ v1 (format stable; no versioned revisions documented) |
| Specification | problemkaputt.de |
SEQ conversions
Community Q&A
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