ACIDCAT . FILE FORMAT REFERENCE

ReCycle RX2 Anatomy

CAT/REX2 IFFsliced loop
rev 2026.07
magic CAT REX2
endian big
container own
sample 43 41 54 20

An .rx2 is a Propellerhead ReCycle loop: an IFF-style CAT group whose form type is REX2, holding big-endian chunks. ReCycle slices a drum or instrument loop into transient-aligned segments and stores the slice markers so a host can retrigger each and follow tempo. The markers hide in a nested CAT/SLCL group. Hover any field or byte to light its span and read the decode. Color marks kind (see the key).

file regions

An IFF CAT group, form type REX2, of big-endian chunks. The slice markers hide in a nested sub-group.

CAT container0x00 . 12 bytes . big-endian

The group header, drawn above: the CAT keyword, the group size, and the REX2 form type.

chunksCREI . GLOB . NAME . RECY . SD

Big-endian IFF chunks: a 4-byte id, a 4-byte size, then the body (padded to even). acidcat decodes the legible strings and reports the rest as regions.

framingid[4] + size[4] BE + body (even-padded)
CREIcreator string, e.g. a ReCycle version
GLOBglobal: tempo, bars/beats
NAMEloop name
SDsample data (the audio)
slice listnested CAT / SLCL

The transient slice markers do not sit at the top level: they live in a nested CAT group whose form is SLCL, one SLCE per slice. acidcat recurses into it to count slices; a flat top-level walk would miss them.

nestingCAT (SLCL) -> SLCE, SLCE, ...
slice countrecursed, depth-bounded against a malformed file
SLCEone transient-aligned slice marker