Sustainability of Digital Formats
Planning for Library of Congress Collections
Sustainability of Digital Formats
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| Introduction | Sustainability Factors | Content Categories | Format Descriptions | Contact | |
| Full name | Macromedia Flash SWF File Format, Version 8 |
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| Description |
Binary file format that Delivers vector graphics (especially animations) and other data types, including "bitmapped" video, over the Internet to the Flash Player. A more complete format description for Flash is offered for SWF_7, version 7 of the specification. In 2005, Adobe purchased Macromedia and a branding changeover began. The documentation for the Flash (SWF) format, version 8, was disseminated from the Adobe Web site but still carried the Macromedia brand on the cover sheet. The October 2005 issue of Macworld magazine reports that the Flash Professional 8 application offers a new video codec called VP6 from a company named On2. |
| Production phase | Used for final-state, end-user delivery. |
| Relationship to other formats | |
| Has earlier version | Macromedia Flash (SWF) Versions 3, 4, 5, and 6, not documented here. |
| Has earlier version | SWF_7, Macromedia Flash SWF File Format, Version 7 |
| Has later version | SWF, versions 9, 10. Not yet documented. |
| May contain | Sorenson encoded video.1 |
| May contain | Screen Video Bitstream Format (ScreenVideo), not documented here. |
| May contain | Raw PCM sampled audio content, not documented here. |
| May contain | ADPCM, (Adaptive Delta Pulse Code Modulation) audio content |
| May contain | MP3_ENC, Audio content |
| May contain | Nellymoser Asao (speech compression) audio content, not documented here. |
| Used by | QuickTime, File Format |
| Other | FLA, Macromedia Flash FLA Project File Format. Explanatory note: SWF files are typically derived from ("save as") a FLA file. |
| LC experience or existing holdings | See SWF_7 |
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| LC preference | See SWF_7 |
| Disclosure | Fully documented. Developed by Macromedia, Inc., now owned by Adobe Systems. |
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| Documentation | The Macromedia Flash (SWF) and Flash Video (FLV) File Format Specification, Version 8, n.d. (copyright notice 2005). Available online in February 2007, but not in March 2009. Specification for SWF version 9 includes details for versions 6, 7, and 8. Specification for SWF version 10 includes definition of action models for previous SWF versions starting with version 3. |
| Adoption | See SWF_7 |
| Licensing and patents | Adobe offered the specification and the right to build tools to produce SWF files via a free license. The license limited creation of software to play SWF files. However, in May 2008, it removed remaining restrictions on use of the specifications. See FAQ from Adobe's Open Screen Project. |
| Transparency | Not transparent; proprietary binary format. |
| Self-documentation | See SWF_7. |
| External dependencies | None. |
| Technical protection considerations | None known to the compilers of this document. |
| Moving Image | |
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| Normal rendering | Good support |
| Clarity (high image resolution) | See SWF_7. |
| Functionality beyond normal rendering | See SWF_7. |
| Sound | |
| Normal rendering | Good support |
| Fidelity (high audio resolution) | See SWF_7. |
| Multiple channels | See SWF_7. |
| Support for user-defined sounds, samples, and patches | See SWF_7 |
| Functionality beyond normal rendering | See SWF_7. |
| Tag | Value | Note |
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| Filename extension | swf |
From the Flash SWF Specification (version 7), p. 9. The Wikipedia article on Adobe Flash (consulted February 2007) includes a list of file types (with extensions) associated with the Flash family. |
| Internet Media Type | application/x-shockwave-flash |
From the Flash SWF Specification, version 7, p. 9. |
| Internet Media Type | application/x-shockwave-flash2-preview application/futuresplash image/vnd.rn-realflash |
Selected from The File Extension Source |
| Magic numbers | Hex: 46 57 53 ASCII: FWS |
For uncompressed files; from the Flash SWF Specification, version 8, p. 267. The next byte in the file provides the version number; for example, Hex 07 (0x07) for version 7. |
| Magic numbers | Hex: 43 57 53 ASCII: CWS |
For compressed files; from the Flash SWF Specification, version 8, p. 267. The next byte in the file provides the version number; for example, Hex 07 (0x07) for version 7. |
| General | See SWF_7. |
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| History | See SWF_7. |
1Flash documentation for version 8 does not state a number for "their" version of Sorenson but describes the codec as a variant of ITU-T (International Telecommunications Union-Telecommunication Standardization Sector) recommendation H.263 (MPEG-4_V). In early 2006, one of Sorenson's compression applications to produce content for Flash offered the Sorenson_3 codec, described by experts as a variant of ITU-T H.264 (MPEG-4_AVC). By late 2006, Sorenson offered new compression applications with other outputs.
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