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On this site you can find some utilities for working with movie files of the Microsoft® ASF format.


ASF Direct Writer for iuVCR

This filter allows you to capture video into the ASF container using third-party codecs…

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WMV Direct

Video editor utility for ASF files that does not recompress movie content…

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Overview of the ASF format

The Advanced Systems Format (ASF) is an extensible file format designed primarily for storing and playing synchronized digital media streams and transmitting them over networks. ASF is the container format for Windows Media Audio and Windows Media Video-based content. The extension “wma” or “wmv” is used to specify an ASF file that contains content encoded with the Windows Media Audio and/or Windows Media Video codecs. For content encoded with third-party codecs the “asf” extension is generally used.

This section provides a general description of the ASF format as background information. The complete ASF specification can be found on the Microsoft Web site.

The primary goals of the ASF format are:

·         To support efficient playback from media servers, HTTP servers, and local storage devices.

·         To support scalable media types such as audio and video.

·         To permit a single multimedia composition to be presented over a wide range of bandwidths.

·         To allow authoring control over media stream relationships, especially in constrained-bandwidth scenarios.

·         To be independent of any particular multimedia composition system, computer operating system, or data communications protocol.

An ASF file can contain multiple independent or dependent streams, including multiple audio streams for multichannel audio, or multiple bit rate video streams suitable for transmission over different bandwidths. The streams can be in any compressed or uncompressed format; however, the best compression is achieved with the Microsoft Windows Media Audio and Video 9 Series codecs. In addition to the standard audio and video media stream types, an ASF file can also contain text streams, Web pages and script commands, and any other arbitrary data type. ASF supports live and on-demand multimedia content.