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Direct Access Archive, or DAA, is a proprietary file format developed by PowerISO Computing for disk image files. The format supports features such as compression, password protection, and splitting to multiple volumes. Because of its proprietary nature, popular disk image mounting programs such as Alcohol 120% and Daemon Tools currently do not support the mounting of DAA images.

Currently there is no published information about the format. Among mainstream applications, it can be opened or converted with PowerISO and MagicISO. Various free open source packages are also available to convert DAA to ISO images.

File Structure

Although lacking official documentation, DAA image files seem to be zlib-compressed ISO images without any added functionality in comparison to ISO. It thus offers no advantage to a zipped ISO image and can be considered a case of vendor lock-in.^[1]

Converting into a Standard Format

PowerISO provides free command-line tools for Linux and Mac OS X which allow you to extract DAA files or convert them into ISO format, however the tools haven't been updated to support the newest version of the DAA format. The PowerISO Windows trial version only supports converting images from DAA files up to 300MB[1], less than half of the capacity of a standard CD.

Daa2iso is an open source command line application has been developed to convert DAA files to ISO files. The program comes with a Windows binary and source code which compiles under Unix-like operating systems when linked to the zlib compression library. A brief tutorial for using the program is available here.

There is a .DAA to .ISO converter for MacOS X available under the GNU license at http://www.twilightedge.com/mac/daaconverter/

Graphical versions of daa2iso have also been made available for Windows and Mac OS X (see external links below).

Features

Due to using freely available compression algorithms, DAA includes the following features that are absent in ISO (but can be obtained by manually compressing ISO files):

• Allows for compression saving space and making it easier to download
• Can be password protected
• Can be split into multiple smaller files

External links

• PowerISO Website
• PowerISO downloads for Windows Linux and Mac OS X
• AcetoneISO is a free CD/DVD management application for Linux that can convert DAA to ISO (with the help of the external 'poweriso' binary)
• daa2iso application for Windows (source code included, and may be compiled for *nix / MacOSX without modification)
  • DAA Converter for Mac OS X, graphical Mac interface for daa2iso

References