MPEG-4

MPEG-4

Microsoft has been an active contributor to the development of MPEG-4 since 1994 and is one of the patent holders of the International Organization for Standardization (ISO) MPEG-4 Visual Standard. Various implementations of MPEG-4 encoders and decoders have been made available through releases of Windows Media Technologies, through the codec download feature in Windows Media Player, and in recent versions of Windows.

Early releases of Windows Media Technologies contained implementations of MPEG-4 video encoders and decoders that were completed before the ISO standard was finalized. These earlier implementations are known as versions 1, 2, and 3 of the Microsoft MPEG-4 Video Codecs. They are visible in GraphEdit as the Microsoft MPEG-4 Video Decompressor Filter (versions 1, 2, and 3), the Mpeg4 Decoder DMO (versions 1 and 2), and the Mpeg43 Decoder DMO (version 3). After the standard was completed, Microsoft shipped the ISO-compliant MPEG-4 Video Codec version 1 (encoder and decoder) and version 1.1 (decoder). This codec interoperates with devices created by several companies.

DirectShow applications can access these codecs through the WM ASF Writer and the WM ASF Reader filters. Although the decoders will be maintained for backward compatibility with legacy content, the encoders are being phased out because of licensing issues. No MPEG-4 encoder ships with Windows Media 9 Series, and it s not guaranteed that the encoders will still be present in future versions of Windows. Nevertheless, if a MPEG-4 encoder is in the system (for example, if Windows Media 7.1 was previously installed), the Windows Media 9 Series components will pick it up. To be more concrete, the encoder will show up in the Windows Media Encoder 9 Series, and it will be available to applications based on the Windows Media Format 9 Series SDK. It will also be visible in GraphEdit.

Multiple companies own patents on the ISO MPEG-4 Visual Standard, and fees are associated with the standard. Microsoft will cover any required fees for shipping MPEG-4 codecs in future Microsoft products, but other fees might apply. (For example, the content provider might need to pay a per-minute fee when streaming content.) Third-party MPEG-4 encoders might be available as DirectShow filters or DMOs, but you might still be subject to license fees for using them in your application. For additional questions, please contact MPEG LA, L.L.C., at 250 Steele Street, Suite 300, Denver, Colorado USA 80206; by telephone at [phone]; by fax at [phone]; or on the Web at http://www.mpegla.com/.

For the official Microsoft position on MPEG-4, see the white paper at http://www.microsoft.com/windows/windowsmedia/wm7/mpeg4.aspx.