aftereffects-aep-parser
This project is dedicated to reverse-engineering, parsing and exposing useful APIs for understanding Adobe After Effects AEP project files. This may be useful for a variety of reasons. For example, one might want to programmatically determine the number of compositions in a project, their resolution(s), framerate, etc. Traditionally, one would need to piggyback the ExtendScript engine running within After Effects to retrieve this information. While this procedure is fairly easy to accomplish, it is exponentially more resource expensive than static file analysis, and requires a running instance of the After Effects Scripting Engine (which can only be run on Windows and MacOS).
Quick Start
go get -u github.com/boltframe/aftereffects-aep-parserpackage main
import (
"fmt"
aep "github.com/boltframe/aftereffects-aep-parser"
)
func main() {
project, err := aep.Open("./my-project.aep")
if err != nil {
panic(err)
}
fmt.Println(project)
}Contributing
Any and all contributions are welcome! There is no official procedure for contributing yet, but please start by opening a new issue describing your findings and anticipated contribution. Thank you!
Research Procedure
After Effects Project files are currently encoded using the Resource Interchange File Format (RIFF) in a Big-Endian byte-ordering (also known as RIFX). This can be confirmed by inspecting the first four bytes of any AEP file which will contain the following ASCII characters: RIFX..... Once parsed into Chunks, you can inspect the internal representation and attempt to understand its structure.
I have found that the online tool Kaitai is extremely helpful for quickly viewing structured binary data. I use the following (possibly outdated) language definition for validating AEP files:
meta:
id: aep
endian: be
file-extension: aep
seq:
- id: magic1
contents: RIFX
- id: file_size
type: u4
- id: magic2
contents: Egg!
- id: data
type: blocks
size: file_size - 4
types:
blocks:
seq:
- id: entries
type: block
repeat: eos
block:
seq:
- id: block_type
type: u4
enum: chunk_type
- id: block_size
type: u4
- id: data
size: block_size
type:
switch-on: block_type
cases:
'chunk_type::list': list_body
'chunk_type::utf8': utf8_body
'chunk_type::cdta': cdta_body
'chunk_type::idta': idta_body
'chunk_type::cmta': utf8_body
'chunk_type::fdta': fdta_body
_: ascii_body
- id: padding
type: u1
if: (block_size % 2) != 0
list_body:
seq:
- id: identifier
type: str
encoding: ascii
size: 4
- id: entries
type: blocks
utf8_body:
seq:
- id: data
type: str
encoding: utf8
size-eos: true
ascii_body:
seq:
- id: data
type: str
encoding: ascii
size-eos: true
idta_body:
seq:
- id: unknown1
type: str
size: 18
encoding: ascii
- id: id
type: u2
fdta_body:
seq:
- id: unknown1
type: str
encoding: ascii
size: 1
cdta_body:
seq:
- id: unknown1
type: str
size: 140
encoding: ascii
- id: width
type: u2
- id: height
type: u2
- id: unknown2
type: str
size: 12
encoding: ascii
- id: frame_rate
type: u2
enums:
chunk_type:
0x4c495354: list
0x55746638: utf8
0x63647461: cdta # Composition data
0x69647461: idta # Item data
0x636d7461: cmta # Comment data
0x66647461: fdta # Folder dataBy making small changes to an After Effects project and uploading it to the Kaitai viewer, you can narrow down on how data is represented, and start to write additional language definitions and structures.