What is the SES file format?
A .ses file is a multitrack session project file created by Adobe Audition and its predecessor, Cool Edit Pro (Syntrillium Software). It does not contain any recorded audio - instead it acts as a recipe, storing references to external audio files (typically WAV files or MP3s) along with the arrangement of those clips across tracks, volume and pan envelopes, effects-rack settings, bus routing, and mix automation data.
The format originated with Cool Edit Pro in the late 1990s and was carried into Adobe Audition 1.0 through 3.0 after Adobe acquired Syntrillium in 2003. A .ses file opens with the four-byte ASCII signature COOL at byte offset 0, a nod to its Cool Edit Pro lineage. The format is binary, little-endian, and proprietary - no public specification exists.
Because .ses stores only arrangement metadata, files are typically just a few kilobytes to a few hundred kilobytes. If the referenced source audio files are moved or deleted, the session opens with broken links; the clips must remain accessible at their original paths.
Adobe Audition 3.0 (2007) was the last release to use the binary .ses format. Starting with Audition CS5.5 (2011), Adobe replaced it with the XML-based .sesx format. Legacy .ses sessions can still be opened in older Audition versions. Cool Edit Pro also generated companion .cel single-track waveform files and .pk peak cache files alongside each .ses session.
Security & safety
RISK: LOWA .ses session is a passive project file with no executable code, so it is low-risk to open. The real-world snag is integrity, not security: because the session only references external audio, moving or deleting the source files (or the Cool Edit .pk peak files) leaves the session with missing/offline clips. Keep the .ses together with its audio. Avoid sketchy 'SES viewer/converter' sites - there's no legitimate standalone .ses viewer; you need Adobe Audition to render it.
Format details
in a nutshellPrograms that open SES files
Windows2 apps
Adobe Audition
Paid The native app. File > Open imports the .ses session (older binary .ses needs a version that still imports it; current Audition then re-saves as .sesx). 
Adobe Audition 3.0 (legacy)
Paid The last version built around the binary .ses format - best fidelity for opening an old Cool Edit/Audition session if you can run it. Technical details
deep spec| File structure | Binary, proprietary; no published specification |
| Magic bytes | "COOL" (4 bytes, ASCII) at byte offset 0 |
| Byte order | Little-endian |
| Audio storage | None - references external audio files on disk; does not embed audio data |
| Typical file size | A few KB to a few hundred KB (arrangement metadata only) |
| Session sample rate | Stored per-session (e.g., 44.1 kHz, 48 kHz, 96 kHz); actual audio lives in referenced files |
| Track contents | Clip positions, volume/pan envelopes, effects-rack settings, bus routing, and mix automation |
| Companion files | .pk peak-cache files and .cel single-track waveform files generated alongside each session |
| Supported platform | Windows only |
| MIME type | application/octet-stream (no registered MIME type; audio/x-adobe-audition-session used informally) |
| Developer lineage | Syntrillium Software (Cool Edit Pro, late 1990s) → Adobe Systems (after 2003 acquisition) |
| Last native version | Adobe Audition 3.0 (2007) |
| Successor format | .sesx - XML-based multitrack session introduced in Adobe Audition CS5.5 (2011) |
| Broken-link behavior | Session opens with missing-clip errors if referenced audio files are moved or deleted |
| Released | Cool Edit Pro (late 1990s); carried into Adobe Audition 1.0-3.0 after Adobe acquired Syntrillium in 2003 |
| Latest version | Adobe Audition 3.0 (2007) - the last version using the binary .ses; Audition CS5.5+ uses the XML .sesx instead |
| Specification | helpx.adobe.com |
SES conversions
Community Q&A
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