Block diagram
SWF files are used by Adobe Flash (AKA Shockwave Flash, Macromedia Flash) to encode rich interactive multimedia content and are, essentially, a container for special bytecode instructions to play back that content. In early 2000s, it was dominant rich multimedia web format (.swf files were integrated into web pages and played back with a browser plugin), but its usage largely declined in 2010s, as HTML5 and performant browser-native solutions (i.e. JavaScript engines and graphical approaches, such as WebGL) emerged.
There are a lot of versions of SWF (~36), format is somewhat documented by Adobe.
This page hosts a formal specification of Adobe Flash (AKA Shockwave Flash, Macromedia Flash) using Kaitai Struct. This specification can be automatically translated into a variety of programming languages to get a parsing library.
meta:
id: swf
title: Adobe Flash (AKA Shockwave Flash, Macromedia Flash)
file-extension: swf
xref:
justsolve: SWF
pronom: fmt/507
# - fmt/{505..507} # Adobe Flash {8..10}
# - fmt/{757..776} # Adobe Flash {11..30}
loc:
- fdd000130 # SWF 7
- fdd000248 # SWF 8
mime: application/x-shockwave-flash
wikidata: Q594447
tags:
- executable
- media
license: CC0-1.0
endian: le
# imports:
# - abc_bytecode
doc: |
SWF files are used by Adobe Flash (AKA Shockwave Flash, Macromedia
Flash) to encode rich interactive multimedia content and are,
essentially, a container for special bytecode instructions to play
back that content. In early 2000s, it was dominant rich multimedia
web format (.swf files were integrated into web pages and played
back with a browser plugin), but its usage largely declined in
2010s, as HTML5 and performant browser-native solutions
(i.e. JavaScript engines and graphical approaches, such as WebGL)
emerged.
There are a lot of versions of SWF (~36), format is somewhat
documented by Adobe.
doc-ref: https://open-flash.github.io/mirrors/swf-spec-19.pdf
seq:
- id: compression
-orig-id: Signature
type: u1
enum: compressions
- id: signature
-orig-id: Signature
contents: "WS"
- id: version
-orig-id: Version
type: u1
- id: len_file
-orig-id: FileLength
type: u4
- id: plain_body
size-eos: true
type: swf_body
if: compression == compressions::none
- id: zlib_body
size-eos: true
process: zlib
type: swf_body
if: compression == compressions::zlib
types:
swf_body:
seq:
- id: rect
type: rect
- id: frame_rate
type: u2
- id: frame_count
type: u2
- id: file_attributes_tag
type: tag
if: _root.version >= 8
- id: tags
type: tag
repeat: eos
rect:
seq:
- id: b1
type: u1
- id: skip
size: num_bytes
instances:
num_bits:
value: b1 >> 3
num_bytes:
value: ((num_bits * 4 - 3) + 7) / 8
rgb:
seq:
- id: r
type: u1
- id: g
type: u1
- id: b
type: u1
tag:
seq:
- id: record_header
type: record_header
- id: tag_body
size: record_header.len
type:
switch-on: record_header.tag_type
cases:
'tag_type::define_sound': define_sound_body
'tag_type::do_abc': do_abc_body
'tag_type::script_limits': script_limits_body
'tag_type::symbol_class': symbol_class_body
'tag_type::set_background_color': rgb
'tag_type::export_assets': symbol_class_body
define_sound_body:
seq:
- id: id
-orig-id: SoundId
type: u2
- id: format
-orig-id: SoundFormat
type: b4
- id: sampling_rate
-orig-id: SoundRate
type: b2
enum: sampling_rates
doc: Sound sampling rate, as per enum. Ignored for Nellymoser and Speex codecs.
- id: bits_per_sample
-orig-id: SoundSize
type: b1
enum: bps
- id: num_channels
-orig-id: SoundType
type: b1
enum: channels
- id: num_samples
type: u4
enums:
sampling_rates:
0: rate_5_5_khz
1: rate_11_khz
2: rate_22_khz
3: rate_44_khz
bps:
0: sound_8_bit
1: sound_16_bit
channels:
0: mono
1: stereo
do_abc_body:
seq:
- id: flags
type: u4
- id: name
type: strz
encoding: ASCII
- id: abcdata
size-eos: true
#type: abc_bytecode
script_limits_body:
seq:
- id: max_recursion_depth
type: u2
- id: script_timeout_seconds
type: u2
symbol_class_body:
seq:
- id: num_symbols
type: u2
- id: symbols
type: symbol
repeat: expr
repeat-expr: num_symbols
types:
symbol:
seq:
- id: tag
type: u2
- id: name
type: strz
encoding: ASCII
record_header:
seq:
- id: tag_code_and_length
type: u2
- id: big_len
type: s4
if: small_len == 0x3f
instances:
tag_type:
value: 'tag_code_and_length >> 6'
enum: tag_type
small_len:
value: 'tag_code_and_length & 0b111111'
len:
value: 'small_len == 0x3f ? big_len : small_len'
enums:
compressions:
0x46: none # F
0x43: zlib # C
0x5a: lzma # Z
tag_type:
0: end_of_file
4: place_object
5: remove_object
9: set_background_color
14: define_sound
26: place_object2
28: remove_object2
43: frame_label
56: export_assets
65: script_limits
69: file_attributes
70: place_object3
76: symbol_class
77: metadata
78: define_scaling_grid
82: do_abc
86: define_scene_and_frame_label_data