Generate or decompile Adobe Flash SWF files using an XML dialect. Inspect and modify the XML by hand, or by using a built in XSLT processor.
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swfmill Build Status

swfmill is a tool to process Adobe Flash (SWF) files. It can convert SWF from and to an XML dialect called “swfml”, which is closely modeled after the SWF file format.

It also provides a libxslt-based XSL transformation engine that supports an extension (“swft”) that helps with generating IDs for SWF objects and can import an SWF as XML using an XPath function (swft:document()).

As a simple application of such functionality, swfmill can pack together a bunch of media files (jpeg and png images, other SWF movies, TrueType fonts) into an SWF as “library objects” for your attachMovie() pleasure.


swfmill is alpha-quality software. It might well not work as it should. Please report your experiences if that seems to be the case, send in (if possible small) SWFs or patches.

You can report bugs or contribute patches via GitHub at


swfmill requires, and the binary releases contain code from:

  • libxml2, © 1998–2003 Daniel Veillard.
  • libxslt/exslt, © 1998-2003 Daniel Veillard.
  • zlib, © 1995-2004 Jean-loup Gailly and Mark Adler.
  • freetype, © 1996-2000, 2002, 2004 David Turner, Robert Wilhelm, and Werner Lemberg.
  • libpng, © 2004 Glenn Randers-Pehrson.

To build, xsltproc is required in addition to the usual GCC build environment.

Some of the test cases require MTASC, and will be skipped if it is not found.

My references to the SWF format were:

Compiling and Installing

On Linux, use the “GNU-standard”

./configure && make && make install

On Windows, if you have use for a tool like this, you know better than me where to put swfmill.exe.


see swfmill -h for general usage options.

convert an SWF (foo.swf) to XML:

swfmill swf2xml foo.swf bar.xml

convert such XML to SWF:

swfmill xml2swf bar.xml meep.swf

Simple swfml Dialect

For library generation, and probably other fun SWF construction, swfmill supports a simplified XML dialect. to create a library swf that includes some assets, construct an XML file that looks like this:

<?xml version="1.0" encoding="iso-8859-1"?>
<movie width="320" height="240" framerate="12">
  <background color="#ffffff"/>
      <clip id="jpg" import="library/testjpg.jpg"/>
      <clip id="png" import="library/testpng.png"/>
      <clip id="swf" import="library/shape.swf"/>
    <font id="vera" import="library/vera.ttf"

and run swfmill:

swfmill simple <the-xml-above.xml> output.swf

output.swf should now contain the specified assets (the JPG, PNGs, other SWF and font) specified.

The file paths in the simple XML are relative to where you start swfmill.

Any <clip import=".."/> that is placed within a tag will be exported for attachMovie with the ID attribute as the linkage ID. For the above example, you can attach library/testjpg.jpg with

_root.attachMovie("jpg", "foo", 1);

The font is also available by its ID, and will contain only the characters specified in its glyph attribute. Make sure you specify the correct encoding in the XML declaration for characters outside the ASCII range.

Shared Libraries

swfmill supports both generation and use of shared libaries. To generate a shared libary, simply put your assets in a <library/> tag just as for attachMovie (see above).

To use a shared library, the library swf has to be available both locally and under its “public” URL. Assuming you have put your library on, and the SWF is also in the library/ subdirectory of where you run swfmill, put this in your definition XML:

<import file="library/library.swf"

That should import all symbols that are exported in library.swf, so they should be available under their name with attachMovie(). Note: this only works with proper assets, not with fonts. If you know how to use a font from a shared library, please tell me.


Copyright © 2005–2007 Daniel Turing. Copyright © 2005–2017 swfmill contributors (see AUTHORS).

swfmill is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License version 2, as published by the Free Software Foundation. See COPYING for details.

Getting Involved

Updates and stuff will be available at the swfmill homepage.

There is a mailing list for swfmill hosted by

The source code of swfmill is hosted on GitHub.

Report bugs or submit patches via GitHub.