PAC File Extension

Have a problem opening a .PAC file? We collect information about file formats and can explain what PAC files are. Additionally we recommend software suitable for opening or converting such files.

What is the .PAC file type?

The .pac filename extension is primarily encountered as part of the standard filename "proxy.pac" conventionally assigned to the Proxy Auto Configuration (PAC) files. Such PAC files are used to manage proxy settings and automate proxy selection by web browsers and other user agents. The PAC file is a text file with a definition of a single JavaScript function (FindProxyForURL) providing a list of domain names and/or IP addresses along with relevant proxy use instructions. To use a PAC file with a web browser, its URL must be specified manually in the browser's proxy settings or determined automatically through the Web Proxy Autodiscovery Protocol (WPAD). Besides "proxy.pac," such files may also be named "proxy.dat" or "wpad.dat."

Alternatively, the .pac extension denotes the Pyro Audio Creator Project (.pac) file type used by Pyro Audio Creator, a commercial audio editor, encoder, and CD/DVD burning/ripping tool by Cakewalk (Twelve Tone Systems, Inc.). The .pac file represents an audio project created in the program's Audio Editor module. It is a RIFF container with uncompressed 16-bit, 44 kHz WAVE audio data inside, being, in fact, a regular wave (.wav) file saved to preserve the current state of editing. By changing the extension from .pac to .wav, any such file can be played or further edited by a range of multimedia software, besides Pyro Audio Creator.

CLO 3D/Marvelous Designer (CLO 3D/MD), proprietary 2D and 3D cloth and garment design software from CLO Virtual Fashion Inc., uses the .pac extension to represent its older garment file format (.pac). Standing for 'Pattern and Cloth,' the .pac extension is assigned to garment files saved in CLO 3D/MD below version 4.00. Always saved with the avatar pose file (.pos) file and a preview icon, the .pac file contains 3D garment and 2D pattern data, while texture images are referenced externally. Such PAC files use a proprietary format and can be opened in CLO 3D/MD only. CLO 3D/MD 4.00 and later save their garment files in the newer Zipped PAC (ZPAC) format by default.

The .pac extension additionally represents the PAC (PU2000, PU2020) subtitle format developed by Screen Electronics for professional broadcast subtitling, just like its twin format RAC (.rac). Besides the subtitle content itself, the .pac (.rac) file saves its time code and position as well as preserves italicized sections. Not directly supported by most general-purpose media players, subtitles in this format (.pac/.rac) can be opened/edited or converted to other subtitle formats using professional subtitle editors like TitleVision 2003 or dedicated converter tools.

Another use of the .pac extension is related to the firmware package (.pac) file format used by a firmware flashing tool named ResearchDownload. Here, the .pac file represents a complete firmware image of an Android-based smartphone device of Chinese origin, built on one of Spreadtrum chipsets. It can be used to update or completely replace the device's firmware, although flashing a wrong .pac may brick the device. PAC files usually have very long names specifying the device model and version, firmware version, and other necessary information.

Referring to the now-obsolete Atari ST platform and its computer-aided design (CAD) program STAD, the .pac extension was used to denote STAD image files. STAD saved its 'high-resolution' (640×400 pixels) drawings as .pac files using a special bitmap format with RLE-compression and either horizontal or vertical byte lines. Such images (.pac) can be viewed in several multi-format images viewers.

As an intuitive abbreviation of 'package' or 'packet,' the .pac extension is additionally used as a generic way to denote package files. A package file is a container archive with its internal filesystem analog, acting as a wrapper for other files. The .pac extension may be used by different software in association with different file formats, quite commonly including standard archive formats like ZIP.

Software to open or convert PAC files

You can open PAC files with the following programs:
Audio Creator LE
Audio Creator LE by Cakewalk Music Software
Marvelous Designer 6 Personal
Marvelous Designer 6 Personal by CLO Virtual Fashion Inc.
Audio Creator
Audio Creator by Cakewalk Music Software
Marvelous Designer 5 Enterprise
Marvelous Designer 5 Enterprise by CLO Virtual Fashion Inc.
Marvelous Designer 3 Enterprise
Marvelous Designer 3 Enterprise by CLO Virtual Fashion Inc.

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