AEP chunk index

Every chunk tag that the py_aep specification identifies in After Effects projects, from A to Z. Tags are case-sensitive: tdum and tduM, mcsp and Mcsp are different chunks. A linked tag has its layout on this site; the others are described, with their layouts where known, in the py_aep specification. Tags such as FEE , Pin , seq and LOm end with a space.

Chunks A to Z

Chunk	Area	Holds
`acer`	Project	Compensate for scene-referred profiles.
`acid`	Project	A composition ID for the Essential Graphics panel (inferred).
`ACsi`	Panel state	Opaque 1,872-byte record in a composition’s `LIST:LSIf`.
`adfr`	Project	Project audio sample rate.
`AFsi`	Panel state	Opaque 1,872-byte record in the root `LIST:LSIf`.
`alas`	Footage	A file or folder path as UTF-8 JSON text.
`angl`	Paint	Angle channel of a paint stroke’s brush dynamics.
`apid`	Footage	ICC profile ID assigned to the footage.
`aRbp`	Effects	One arbitrary-data parameter value (curves, colour ranges, plug-in state).
`ARsi`	Panel state	Opaque 1,872-byte record in the render queue’s `LIST:LSIf`.
`blsi`	Layers	The layer’s alternate source (media replacement).
`blsv`	Layers	4-byte value before `blsi` in the Source Options group.
`btov`	Text	Little-endian value after an Essential Graphics text override.
`CapL`	Essential Graphics	4-byte value in a caption list.
`CcCt`	Essential Graphics	Controller count.
`CCEx`	Essential Graphics	1-byte media replacement option.
`CCId`	Essential Graphics	4-byte ID in a property reference.
`cdat`	Properties	A stream’s static value.
`CDef`	Essential Graphics	A controller’s default value.
`cdrp`	Compositions	Drop-frame timecode display.
`cdta`	Compositions	Composition settings: timing, size, background, motion blur, flags.
`CFEd`	Essential Graphics	1-byte Source Text controller option.
`CLId`	Essential Graphics	4-byte ID in a property reference.
`cmta`	Items, layers	Item or layer comment, UTF-8 followed by NUL bytes.
`comr`	Compositions	1-byte media replacement wrapper flag (AE 17 on).
`cpid`	Project	Profile ID of the working colour space.
`CprC`	Essential Graphics	Count of `LIST:CPrp` children.
`CPTm`	Essential Graphics	8-byte value in the Essential Graphics definition.
`CROI`	Essential Graphics	8-byte value in the Essential Graphics definition.
`CsCt`	Essential Graphics	String count of a localised string or caption list, little-endian.
`CSEd`	Essential Graphics	1-byte Source Text controller option.
`CSGe`	Essential Graphics	1-byte group controller option.
`CSMd`, `CSMe`, `CSMh`, `CSMp`, `CSMs`, `CSMt`, `CSMw`	Essential Graphics	Media replacement controller settings.
`CTov`	Essential Graphics	4-byte Source Text controller value.
`CTyp`	Essential Graphics	Controller type, which sets the layout of `CVal` and `CDef`.
`CVal`	Essential Graphics	A controller’s current value.
`dcui`	Footage colour	1-byte colour management flag.
`dmtr`	Paint	Diameter channel of a paint stroke’s brush dynamics.
`drop`	Footage	Drop-frame flag of the media timecode.
`dwga`	Project	Working gamma, little-endian.
`EfDC`	Effects	Number of effect definitions, little-endian.
`elab`	Effects	One byte found inside effect data.
`embp`	Footage colour	1-byte embedded-profile flag.
`empd`	Footage colour	Marks that a `Utf8` with the media’s declared colour space follows.
`engv`	Effects	Value between an effect’s `tdmn` and its `LIST:sspc`.
`epid`	Footage colour	ICC profile ID of the profile the media embeds.
`ewin`	Panel state	28-byte Effect Controls window record.
`ewot`	Panel state	Effect Controls outline state, one word per row.
`expr`	Properties	Expression text with a NUL, in files older than version 92.0.
`fcid`	Project	The active item.
`fdta`	Items	Root folder record, 14 bytes.
`fiac`, `fidi`, `fifl`, `fimr`, `fiop`, `fipc`, `fipl`, `fips`, `fits`, `fitt`, `fivc`, `fivi`, `fmpl`, `foac`, `fots`, `fott`, `fovc`, `fovi`, `ftts`	Panel state	Chunks of an item UI record, which runs from `fvdv` to `fifl`: tab and viewer state, view options (`fips`), viewer type name (`fitt`), tab type name (`fott`).
`flow`	Paint	Flow channel of a paint stroke’s brush dynamics.
`fnam`	Effects	Wrapper for an effect instance’s match name.
`fpms`, `fpmv`, `fpol`, `fpov`, `fpsz`	Puppet	Puppet effect mesh and outline data.
`ftgi`	Footage	Footage item times.
`fth5`	Masks	Variable-width mask feather points.
`ftwd`	Panel state	56-byte panel view record, nearly always zero.
`fvdv`	Panel state	First chunk of an item UI record.
`gdta`	Compositions	8-byte record in a guide list.
`hdrm`	Footage colour, render queue	1-byte HDR flag.
`head`	File	File version, saving application, next item ID.
`idpc`	Items	Number of `idpi` that follow, little-endian.
`idpi`	Items	ID of a composition this one depends on, little-endian.
`idta`	Items	Item header: type, ID, label, proxy and footage flags.
`iide`	Items	Item ID, little-endian copy.
`init`	Puppet	1-byte value in the Puppet ARAP group.
`ipws`	Footage colour	1-byte colour management flag.
`ldat`	Properties	The items of a typed list: keyframes, guides, vertices or render queue records.
`ldta`	Layers	Layer record.
`lhd3`	Properties	Header of a typed list.
`linl`	Footage colour	Interpret as linear light, little-endian.
`LIST`	File	A list of chunks with a four-character type.
`LIST:Als2`	Footage	A file or folder path.
`LIST:aRbs`	Effects	Values of an arbitrary-data effect parameter.
`LIST:btdk`	Text	The text documents of a Source Text property, as one raw body.
`LIST:btds`	Text	The Source Text property: a stream plus its text documents.
`LIST:btgu`	Text	Identifiers of the text documents.
`LIST:CapS`	Essential Graphics	Caption strings.
`LIST:CCtl`	Essential Graphics	One controller.
`LIST:CIF2`, `LIST:CIF3`, `LIST:CIFO`	Essential Graphics	The three copies of a composition’s Essential Graphics definition.
`LIST:CLay`	Compositions	The three custom 3D views, as hidden camera layers.
`LIST:CLRS`	Footage colour	Interpret Footage colour management settings.
`LIST:CPPl`	Project	ICC profile pool.
`LIST:CPrp`	Essential Graphics	A property reference.
`LIST:CpS2`	Essential Graphics	A localised string, one text per locale.
`LIST:CTRE`	Panel state	A copy of the project panel tree state.
`LIST:dats`	Compositions	Data-driven sources.
`LIST:DLay`	Compositions	The Default 3D view, a hidden camera layer.
`LIST:EfDf`	Effects	One effect definition.
`LIST:EfdG`	Effects	Project-level effect definitions, one per effect type used.
`LIST:Ewst`	Panel state	Effect Controls panel state of one layer.
`LIST:ExEn`	Project	Expression engine.
`LIST:FEE`	Panel state	Timeline panel state of a composition.
`LIST:Fold`	Items	The project’s root folder.
`LIST:GCky`	Shapes, layer styles	Gradient values.
`LIST:GCst`	Shapes, layer styles	A gradient property.
`LIST:Gide`	Compositions, layers	Ruler guides.
`LIST:gpuG`	Project	GPU renderer.
`LIST:Item`	Items	One folder, composition or footage item.
`LIST:Layr`	Layers	One layer.
`LIST:list`	Properties	A typed list: `lhd3` and `ldat`.
`LIST:LItm`	Render queue	Comments and output modules of the render queue items.
`LIST:LOm`	Render queue	The output modules of one render queue item.
`LIST:LRdr`	Render queue	The render queue.
`LIST:LSIf`	Panel state	Wrapper for one 1,872-byte panel record.
`LIST:mnfo`	Footage	Media timecode information.
`LIST:mrky`	Markers	Marker values.
`LIST:mrst`	Markers	The `ADBE Marker` property of a layer or composition.
`LIST:Nmrd`	Markers	One marker.
`LIST:om-s`	Masks, shapes	A Bezier path property.
`LIST:omks`	Masks, shapes	The path values of a `LIST:om-s`.
`LIST:otky`	Properties	Orientation values, one per keyframe.
`LIST:otst`	Properties	The body of `ADBE Orientation`.
`LIST:OvdG`	Essential Graphics	Older override container, AE 15 only.
`LIST:OvG2`	Essential Graphics	Override group of a layer’s Essential Properties.
`LIST:parT`	Effects	Parameter definitions of an effect.
`LIST:Pefl`	Project	Effects used in the project, one match name each.
`LIST:Pin`	Footage	One footage source: file, solid or placeholder.
`LIST:pnts`	Paint	Brush dynamics of one paint stroke.
`LIST:PRin`	Compositions	The 3D renderer and its options.
`LIST:PTRE`	Panel state	Project panel tree state (inferred).
`LIST:SecL`	Compositions	A hidden layer named Markers that holds the composition markers.
`LIST:Sfdr`	Items	A folder’s contents.
`LIST:sfnm`	Project	The Solids folder’s name and ID.
`LIST:shap`	Masks, shapes	One Bezier path value.
`LIST:SLay`	Compositions	The six orthographic 3D views, as hidden camera layers.
`LIST:sspc`	Effects	One effect instance (not the footage chunk `sspc`).
`LIST:StVc`	Footage	A list of strings: the frame files of an image sequence.
`LIST:tdbs`	Properties	A property stream.
`LIST:tdgp`	Properties	A property group.
`lnrb`	Project	Present when colours are blended with 1.0 gamma.
`lnrp`	Project	Present when the working space is linearised.
`mcsp`	Footage colour	Marks that the embedded colour space’s envelope follows.
`Mcsp`	Footage colour	Marks that the media colour space’s envelope follows.
`mdla`	Layers	256 bytes on 3D model layers, not understood.
`mdld`	Footage	Geometry of a 3D model footage item, little-endian doubles.
`mdls`	Footage	Settings of a 3D model footage item.
`mdlv`	Layers	8-byte little-endian value on 3D model layers.
`menv`	Puppet	Ends the Puppet mesh group, with `PEvr`, `PEsz` and `PEdt`.
`mkif`	Masks	Mask settings: inverted, locked, motion blur, feather falloff, mode, ID.
`mrid`	Project	Item ID of the Media Replacement Comps folder, little-endian.
`mtif`	Tracker	Motion tracker information.
`mtov`	Layers	Little-endian value of a 3D model material.
`mtpd`	Tracker	Options of the tracking plug-in (inferred).
`mtpr`	Tracker	20-byte tracker record.
`nhed`	File	Compact copy of project settings.
`NmHd`	Markers	Marker header.
`nnhd`	File	Project settings: time display, frame counting, colour depth.
`numS`	Compositions	4-byte count in `LIST:dats`.
`oacc`	Project	Count of `ocid` chunks that follow.
`ocid`	Project	A composition ID of the Essential Graphics panel list (inferred).
`ocsp`	Footage colour	Marks that the assigned colour space’s envelope follows.
`olsz`	Puppet	4-byte value in the Puppet ARAP group.
`omtn`	Masks, shapes	Per-vertex RotoBezier tensions.
`opct`	Paint	Opacity channel of a paint stroke’s brush dynamics.
`opti`	Footage	The importer’s own record for the source; its layout depends on the importer.
`otda`	Properties	One orientation value: X, Y, Z angles.
`otln`	Panel state	Timeline outline state, one word per row.
`pard`	Effects	One effect parameter definition, the SDK’s `PF_ParamDef`.
`parn`	Effects	Number of parameters in `LIST:parT`.
`pcms`	Project	Marks that the colour management settings JSON follows.
`pdnm`	Effects	Wrapper for a parameter name, or popup items separated by `\|`.
`pdvc`	Project	Marks that the display colour space follows.
`PEdt`, `PEsz`, `PEvr`	Puppet	Puppet mesh group data: two 4-byte values, then opaque data (`PEdt`).
`pgui`	Effects	A 16-byte GUID.
`pjef`	Project	One effect match name in `LIST:Pefl`.
`pnta`	Paint	Paint stroke type.
`pprf`	Project	One ICC profile of the pool.
`ppSn`	Panel state	8-byte double in `LIST:FEE`.
`prda`	Compositions	Options of the 3D renderer: 12, 16, 20 or 52 bytes.
`prgb`	Footage colour	1-byte colour management flag.
`prin`	Compositions	104-byte renderer record.
`PwCs`	Project	Marks that the working colour space follows.
`qtlg`	Project	Legacy QuickTime gamma flag.
`RCom`	Render queue	Comment of a render queue item.
`Rhed`	Render queue	Render queue header.
`rndn`	Paint	Roundness channel of a paint stroke’s brush dynamics.
`Roou`	Render queue	Output format and video and audio settings of an output module.
`Ropt`	Render queue	Options of the output format, in the format’s own layout.
`Rout`	Render queue	One entry per Render Queue panel row (inferred).
`sdat`	Effects	An effect’s sequence data, kept by the plug-in.
`seq`	Panel state	Timeline view settings.
`sfdt`	Items	Folder flag word.
`sfid`	Project	Item ID of the Solids folder, little-endian.
`shph`	Masks, shapes	Path header: flags and the bounding box the points are normalised to.
`Smax`, `Smin`	Essential Graphics	A slider controller’s maximum and minimum, doubles.
`sspc`	Footage	Cached properties of a footage source, with Interpret Footage settings.
`strt`	Footage	The media’s start timecode, little-endian.
`StVS`	Footage	String count of `LIST:StVc`, little-endian.
`svap`	File	The saving application’s build word.
`tdb4`	Properties	Stream metadata.
`tdli`	Properties	Mask reference of an effect path parameter.
`tdmn`	Properties	Match name of the next child.
`tdpi`, `tdps`	Properties	Layer reference of an effect parameter, and its companion.
`tdsb`	Properties	Group or stream flags.
`tdsn`	Properties	Wrapper for a display name.
`tdum`, `tduM`	Properties	A stream’s minimum and maximum.
`tmds`	Paint	When each vertex of a stroke was drawn.
`tpds`	Tracker	4-byte value in the trackers group.
`tpsp`	Paint	9-byte records of a paint stroke.
`tver`	Tracker	First chunk of the motion trackers data in the layer’s `ADBE MTrackers` group.
`Utf8`	File	A UTF-8 string, the whole body.
`vfdn`	Text	Wrapper for a variable font axis name (AE 2026).
`wsnm`	Project	Name of the workspace in use when saved, UTF-16LE.
`wsns`	Project	Byte length of the workspace name.

Not yet on this site

The field layouts of the footage source records (LIST:Pin, sspc, opti and its per-importer variants), footage colour management, masks and shapes, paint, markers, effects and their parameter definitions, text documents, the render queue, Essential Graphics and panel state are in the py_aep specification but not yet reproduced here. The text documents in LIST:btdk are a single COS body. Much of the panel state is opaque even there.

.AEP File Format – Chunk index

Chunks A to Z

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