Codec Central - NetShow



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NetShow

The current release of NetShow is 2.1. NetShow 3.0 is currently in limited beta and offers a dramatic step forward in quality and functionality, including the addition of technology gained through Microsoft's acquisition of VXtreme. The information in Codec Central is specific to NetShow 3.0.

Microsoft's NetShow architecture is aimed at providing the best multimedia delivery over networks, from 14.4 modems to high-speed LANs. There is an impressive range of audio and video codecs built into NetShow 3.0. Combined with a powerful media server, this is a powerful solution for networked media.

Technically, the term "NetShow" refers to the client installation and the server software. Netshow clients are built on top of the DirectShow architecture. Because of this, NetShow has access to its own codecs, and also those for DirectShow, Video for Windows (ACM/VCM), and QuickTime.

Netshow media on WWW pages may be viewed via ActiveX components (for Internet Explorer), plug-ins (for Netscape Navigator), or stand-alone viewers.

NetShow servers support "true streaming" (in their case, called "intelligent streaming"): the ability to guarantee continuous delivery of media even if the networks' performance degenerates. If this happens, NetShow will automatically use send less video data (thus reducing the quality). If the amount of available bandwidth decreases more, NetShow will degrade video quality further, until only the audio is left. Microsoft says that their implementation provides the most graceful handling of this situation.

The latest free downloads, as well as more information, are available at Microsoft's NetShow site.

Note: The codecs listed below are included in the NetShow client install. Other DirectShow codecs will also work, but may not be available for all platforms, or may not be optimal for networked use.

NetShow Video Codecs

Codec (Primary Use)	Pros	Cons	Availability
MPEG-4	Optimized for very good quality at low data rates	Often requires higher data rates than H.263	Standard client (2.0, 3.0)
Vivo V263 (H.263)	Optimized for good quality at very low data rates	Not well suited to high data rates; quality may be lower than MPEG-4	Full client (3.0)
VDOnet VDOwave	Optimized for good quality at low data rates	Not well suited to high data rates; quality may be lower than MPEG-4	Full client (2.0, 3.0)
ClearVideo 1.3	Good quality on relatively low-motion video, and at higher data rates	Requires high-end system for proper playback; not optimal for high motion or low data rates	Decoder in Full client (2.0, 3.0) Encoder available from Iterated Systems
Duck TrueMotion RT	Excellent image quality at very high data rates, typically for private intranets	Not appropriate for most public Internet connections	Full client (2.0, 3.0)
Indeo 3.2	Supports playback on low-end machines	requires high data rates low image quality Not included in 3.0 client install	Was in 2.0, no longer in 3.0
Indeo Video Interactive 4.1	Excellent image quality (similar to MPEG)	requires high data rates Not included in 3.0 client install	Was in 2.0, no longer in 3.0

NetShow Audio Codecs

Codec (Primary Use)	Pros	Cons	Availability
MPEG layer III audio music (8-128kbps)	High quality reproduction of music, especially intrumental/orchestral	Not as well-suited to voices or vocal music at lower datarates	Standard client (3.0)
Voxware MetaSound general (8-48kbps)	High quality voice, music, etc. Flexible across range of material & data rates	Requires higher datarates than MetaVoice	Standard client (2.0, 3.0)
Voxware MetaVoice voice (2.4Kbps, 8khz)	Decent voice quality at extremely low bitrates	Not appropriate for music; requires fairly "clean" speech to work well	Standard client (2.0, 3.0)
Voxware RT29 voice (2.9Kbps, 8khz)	Decent voice quality at extremely low bitrates	Not appropriate for music; requires fairly "clean" speech to work well	Standard client (3.0)
Lernout & Hauspie CELP voice (4.8Kbps, 8khz)	Decent voice quality at low bitrates	-	Full client (2.0, 3.0)
Vivo V723 (G.723) voice (6.4Kbps, 8khz)	Standards-based	Not as highly optimized as some proprietary codecs	Decoder in Full client (2.0, 3.0) Encoder available from Vivo
Vivo Siren general (16Kbps, 16khz)	-	-	Decoder in Standard client (2.0, 3.0) Encoder available from Vivo