Containers and id spaces

How Live's files are packed: which are gzip-compressed XML and which are binary, what lies beside them, and how the ids inside a document are numbered.

Documents

• .als (Live Set), .adg (rack preset), .adv (device preset), .alc (clip): gzip-compressed UTF-8 XML.
  • Recognized by the gzip magic 1f 8b. Plain XML (starting with <?xml) is accepted too.
  • Root element <Ableton …> (see versions.md).
• .agr (groove): often gzip XML, but many factory grooves use a legacy binary format ("103 of 219").
• Sets from before Live 8.2 are binary, magic AB 1E. livesaver reports these as unsupported.
• Live writes tab indentation, one element per line, and self-closing elements in the form <Name Value="…" />.
  • When a value contains ", Live uses single quotes: Value='say "hi"'.
  • Parsers must accept both quote styles.
• livesaver writes changed values as Value="…" with "; Live 12 reads that back.
• Compression ratio on a real 7.4 MB set: 45.2 MB XML (6.1×), 611k elements.

.amxd (Max for Live device)

Source: Ableton maxdevtools (amxd_textconv.py, freezing_utils.py).

The file is a sequence of chunks, each a 4-byte ASCII tag, a u32 LE length, then the payload:

• ampf: a 4-byte device type
  • aaaa audio effect
  • mmmm MIDI effect
  • iiii instrument
  • nagg MIDI generator
  • natt MIDI transformation
• meta: ignored.
• ciph: the device is encrypted.
• ptch: the patcher, as JSON that may be NUL-terminated.

A frozen ptch starts with mx@c:

• bytes 8–16 hold a u64 BE offset to the footer
• the footer is dlst + a u32 BE size, followed by dire entries
• each entry holds type, fnam, sz32, of32, vers, flag and mdat (HFS+ seconds; everything big-endian)
• the first entry is the device itself

Only the type code (head[:4] == "ampf", type = head[8:12]) is needed to pick the collect folder:

.asd (analysis, Live 12)

• Magic 06 49, then a u64 LE entry count, a u32 position table and 17 constant bytes.
• Then documents, each starting with AB 1E 56 78 and version 5: SampleData, AufTaktData.
• Live regenerates .asd files written by other tools. livesaver only copies them next to their sample.
• Source for the layout: abletoolz asd/FORMAT.md (GPL, used for facts only).

.alp (pack)

• Starts with pl-a plus the offset of a table of contents stored at the end of the file.
• Usually gzipped as a whole; samples are stored as name.wav.flac. Not planned.

Id spaces inside a Set

1. Chain-local Id attributes on list items: unique within their parent list. They are sparse, because Live never reuses numbers.
2. Pointee ids. One counter, LiveSet/NextPointeeId, is shared by Pointee, every *AutomationTarget / *ModulationTarget, and controller targets.
   • They must be unique and < NextPointeeId; duplicates make Live report "Pointee IDs are not unique" / "corrupt".
   • Live 9 has no NextPointeeId.
3. RelativePathElement ids (Live 10 old-format FileRefs only).
   • New ones are allocated as max + 1 over all RelativePathElement Ids in the document.
   • They are separate from the pointee ids; keep them apart (livesaver RelPathIds).
4. MIDI notes (Live 11+): MidiNoteEvent@NoteId is unique per clip, plus Notes/NoteIdGenerator/NextId.

When grafting devices between Sets:

• give the subtree fresh pointee ids and bump NextPointeeId
• strip KeyMidi bindings (they crash Live 12 on load)