Sustainability of Digital Formats: Planning for Library of Congress Collections

Pro Tools session files, identified in later versions by the file extensions PTX, PTF and PTS, are essentially metadata manifests of all elements and assets associated with a specific session in the Pro Tools proprietary music production software, developed and maintained by Avid Technology, Inc.. (Avid also supports the Sibelius music notation application.) Session files importantly do not contain audio data itself but instead include maps or references to audio files, MIDI data, track configurations, as well as edit and mix information used to create the specific session, as described in Pro Tools Reference Guide Version 2024.6 (p. 8). Note that Pro Tools distinguishes between "sessions" which are used for individual recording and mixing workflows and stored on a local hard drive or other media and "projects" which are designed for collaboration and stored online in Avid cloud space and cached locally. Interestingly, Avid notes that "we designed and architected this new Project format to not only simplify collaboration, but to lay the groundwork for new workflows we have planned for the future—both locally and in the cloud. Sessions aren't going away, but we see a big opportunity to offer new and extensible workflows in the future with Projects." ProToolsProduction in Understanding The Session File Structure says that "this [session] file should be regarded as the brain behind the session. Despite being deceptively small in size, this single file has a lot of work on its hands, every region placement, automation breakpoint, track height, track name… You get the idea, is stored within this file." Pro Tools can only open one session file at a time but more than one session files is permitted in a project to "create multiple versions of a session or back up your editing and mixing work".

According to Avid Knowledge Base: Pro Tools Session Compatibility and Interchange (dated November 19, 2024), the file extension for session files changed over time with specific versions: Pro Tools 10+ released in 2011 (.ptx); Pro Tools 7 released in 2005 (.ptf); and, Pro Tools 6 released in 2003 and earlier versions (.pts). Tyler Thorsted goes into more detail in his Pro Tools Sessions post about earlier file extensions and versions: "For versions 1 and 2 of Pro Tools, there was no official extension for the session files, but starting with version 3, you might often find the extension PT3, then PT4, and PT5. With version 4, there was also a version P24 extension used when Pro Tools version 4 made the leap to 24bit."

FYI that Pro Tools Session Template files use the extension ptxt but these are distinct from session files. Session template files contain session settings that the user wants to replicate for other sessions. FileInfo.com notes that "the PTXT format was introduced in version 10 of Pro Tools when it replaced the old .PTT Template format."

No information about the structure of proprietary Pro Tools session files is publicly available. Comments welcome. Examples of PTX files are available as part of sample session packages from Voyage Audio among others. Examples of 2003 PTS files are available from DiSKotech | Pro Tools Templates and MIDI files (link via Internet Archive).

The Pro Tools application supports a variety of file formats that can be included as mapped assets in session files, as listed in Avid Knowledge Base: Pro Tools Audio File Type and Session Support (dated March 24, 2023). Files with native import and export support include: WAVE Audio File Format with LPCM audio, WAVE RF64 (not separately described but see summary in WAVE Audio File Format), Dolby Atmos, AIFF File Format with LPCM Audio, MXF Operational Pattern Atom (OP-Atom) and MXF with LPCM audio. Other files types can be imported but will be converted to the current session or project file format on import while a few others can only be exported.

Pro Tools is an industry standard and highly adopted digital audio workstation with both Mac OS and Windows platforms (although note some known issues from December 2024 with macOS Sonoma and Sequoia). Access is via tiered subscription options with expanded features at higher levels. According to Why Pro Tools Music Creators Go Further (Avid 2022), "Artists, producers, and engineers such as Pharrell, Alicia Keys, Jack Antonoff (Taylor Swift, Lana Del Rey), Benny Blanco (Justin Bieber, Kanye West), Andrew Scheps (Adele, Metallica), and countless others have crafted a whole generation of hits—all from within Pro Tools." The website Production Expert reports that "as of December 31, 2022, Avid, the maker of Pro Tools, had more than 500,000 paid cloud-enabled software subscriptions...In an earnings call to investors, the software and hardware company reported that paid Cloud-enabled software subscriptions increased by approximately 23,100 during the quarter to approximately 506,000 as of December 31, 2022, an increase of 23.2% year-over-year."

Avid Technology, Inc. hosts an active Avid Pro Audio Community forum. It also offers Pro Tools certifications via coursework.

Unknown since no public documentation about format structure. Comments welcome.

Accessibility Features

Session files have no specific features to support accessibility. At a high level, because they provide metadata in the form of mapping to assets and documenting changes, they provide information about the contents of the session but these are not translated for screen readers. See also supported file types in Relationships. Comments welcome.

For versions 1 and 2 of Pro Tools, there was no official extension for the session files, but starting with version 3, you might often find the extension PT3, then PT4, and PT5. With version 4, there was also a version P24 extension used when Pro Tools version 4 made the leap to 24bit.