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The quality, frame rate, and frame size of your NetShow™ content is largely
determined by the codec, or compressor/decompressor technology you select when
creating content. NetShow's codec independence means that you can choose from
a variety of codecs and use the ones that best suit your tastes and your content.
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Content Creation Authoring Guide.
Codecs (compressors/decompressors) are drivers that convert from one format type to another. Typically, a codec converts between a compressed format and an uncompressed format. By using codecs for compressing audio and video data into smaller packages, network and multimedia applications provide richer and fuller content and don't consume as much hard disk space or network bandwidth as non-compressed methods.
Codec independence is one of the key benefits of Microsoft NetShow. Most other similar technologies use a proprietary codec (for example, one that can only be used by that one application; other codecs cannot be applied). Microsoft NetShow offers the content author and end user a well-rounded suite of bundled and stand-alone-third-party codecs for voice, music, images, and video, at a variety of bit rates. This gives you more options, more flexible, higher-quality content, and — since the codecs can be upgraded independent of NetShow,— faster innovation.
The average user doesn't even have to know what a codec is to use NetShow content; they just click on NetShow content and it plays. For the developer of NetShow content, however, there are some things about codecs they should learn.
Audio codec is shown at the top, and video codec at the bottom of each cell.
Please refer to the list of
codecs that ship with NetShow 2.0 for a more complete list, and to the
Content Creation Authoring
Guide for a detailed discussion on the topic. This chart provides baseline,
or lowest common denominator information. NetShow can be greatly optimized for
your particular content, and you should look at this as a starting point and
adjust variables such as which codec you choose, the frame rate, and audio/video
quality depending on your initial results and configuration.
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Type of Content |
Modem Speed (28.8 Kbps) |
ISDN Speed (56 Kbps) |
Intranet Speeds (110 Kbps) |
| Audio Only |
MPEG Layer-3 Format: 20 Kbps, 11,025 Hz, Mono |
MPEG Layer-3 Format: 48 Kbps, 22,050 Hz, Mono |
MPEG Layer-3 Format: 48 Kbps, 22,050 Hz, Mono |
| Illustrated Audio - Audio is Voice |
MPEG Layer-3 Format: 8 Kbps, 11,025 Hz, Mono Loss Tolerant JPEG Images |
MPEG Layer-3 Format: 16 Kbps, 11,025 Hz, Mono Loss Tolerant JPEG Images |
MPEG Layer-3 Format: 48 Kbps, 22,050 Hz, Mono Loss Tolerant JPEG Images |
| Illustrated Audio - Audio is Music |
MPEG Layer-3 Format: 8 Kbps, 11,025 Hz, Mono Loss Tolerant JPEG Images |
MPEG Layer-3 Format: 16 Kbps, 11,025 Hz, Mono Loss Tolerant JPEG Images |
MPEG Layer-3 Format: 48 Kbps, 22,050 Hz, Mono Loss Tolerant JPEG Images |
Voice and Video Advanced Codec Information
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MPEG Layer-3 Format: 8 Kbps, 11,025 Hz, Mono MPEG-4 Video High Speed Compressor Advanced: Image size: QCIF (176 x 144) Frame rate: 5 - 10 fps |
MPEG Layer-3 Format: 8 Kbps, 11,025 Hz, Mono MPEG-4 Video High Speed Compressor Advanced: Image size: QCIF (176 x 144) Frame rate: 10 - 15 fps |
MPEG Layer-3 Format: 8 Kbps, 11,025 Hz, Mono MPEG-4 Video High Speed Compressor Advanced: Image size: QCIF (176 x 144) Frame rate: 15 fps |
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Music and VideoAdvanced Codec Information
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MPEG Layer-3 Format: 8 Kbps, 11,025 Hz, Mono MPEG-4 Video High Speed Compressor Advanced: Image size: QCIF (176 x 144) Frame rate: 5 - 10 fps |
MPEG Layer-3 Format: 16 Kbps, 11,025 Hz, Mono MPEG-4 Video High Speed Compressor Advanced: Image size: QCIF (176 x 144) Frame Rate: 10 - 15 fps |
MPEG Layer-3 Format: 20 Kbps/11,025 Hz Mono - 48 Kbps/11,025 Hz Mono MPEG-4 Video High Speed Compressor Advanced: Image size: QCIF (176 x 144) Frame Rate: 15 fps |
There are many codecs to choose from when creating NetShow content. We chose these codecs as a quick guideline for the following reasons:
How Content Developers Get Codecs
NetShow uses codecs that conform to the ACM/VCM standards for compression technology. That means that when a system comes with a set of ACM/VCM codecs, NetShow can take advantage of them from any application that supports them. For example, even though Adobe Premiere doesn't explicitly support NetShow, it does allow a content developer to create AVI files that use the same codecs that NetShow uses. Therefore, the content developer can use their favorite NetShow tools to use the codecs that are already installed on the system.
When you install the 
NetShow Tools,
it automatically installs many codecs. Please refer to the list of
codecs that ship with
NetShow 2.0 for a more complete list of these codecs.
When considering which codecs to create content with, it's important to fully understand that when you create content with a particular codec or codecs, in order to be able to play back that content the users will also have to have those codecs installed. Therefore, you must know how your customers will get the codecs necessary to play back content.
How to Create Content That Your Users Will Be Able to Play
You have several options.
Use Only Codecs that are Core Client Install
The most conservative approach is to develop content using codecs that ship in all delivery mechanisms. For NetShow, that means using codecs that ship in the Core Client Install. The codecs shipped in the Core Client Install also ship with the Full Client Install, Internet Explorer 4.0, and the NetShow Tools. These codecs are: MPEG Layer 3, MPEG-4, G.723.1, H.263, and Lernout & Hauspie. Lernout & Hauspie will not be made available crossplatform. Using only codecs that are in the Core Client Install is recommended.
Use Codecs that are in the Full Client Install, but not in the Core Client Install.
This approach works well if you plan to include a link on the HTML page on which the
NetShow content resides, or a page preceding the NetShow content
that sends them to
http://www.microsoft.com/netshow/download/player.htm to
install the Full Client. The advantage of this approach is that that page contains links
to the players for Windows NT 3.51, Windows 3.x, Macintosh, and Unix clients as
well, so it will allow your customers more options to choose from. It also makes
the NetShow player work from any browser (unlike using codebase, which
works from Internet Explorer clients only).
It's important to note that the end user will not necessarily know what codec they need. All content providers using VDOnet, Voxware, or Duck codecs must provide a link to install the full player or use the IFRAME code we supply below to make sure that they have the right codecs for the content.
Use Codecs that Aren't in Either Install Automatically but are Compatible with NetShow.
If a codec manufacturer comes out with an ACM/VCM-compliant codec that suits your content well, you can go ahead and use it even if it doesn't ship in any of the existing client installs. You can use the codebase listed in the "How Users Can Get the NetShow Client and Its Codecs" table below. The disadvantage of this approach is that codebase works on Internet Explorer clients only. Alternatively, you can consult the codec manufacturer for instructions on how to link to a specific page on their Web site that provides the user with an installation of their codec.
How Users Can Get the NetShow Client and Its Codecs
| Install | How | Comments |
| Full Client |
Link to
http://www.microsoft.com/netshow/download/player.htm
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1.6 Mb in size. Includes NetShow Player plus many codecs. This links to a page, not to the executable. This is important because that page will offer downloads for other platforms (Windows 3.x, Macintosh, and Unix) |
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Core Client Use Codebase to Get Individual Codecs |
<OBJECT ID="NSPlay" WIDTH=160 HEIGHT=128 CLASSID="CLSID:2179C5D3-EBFF-11CF-B6FD-00AA00B4E220" |
800 Kb in size. Includes NetShow Player plus a limited set of codecs. Keep in mind that using codebase is the only way to install the Core Client, and will work for Internet Explorer clients only. For cross-platform clients like Windows 3.x, Macintosh, and Unix clients you will want to offer a link to the Full Client Install page as described above. |
Note: Codebase is used in an HTML page to check to see if the user's computer already has an application installed, and if it is the current version. If they do already have the current version installed, it will just go on to play the content. If they do not have it installed, or if it is not the current version, it will automatically go to the specified Web site and start the installation. The advantage of using this approach is that the client doesn't have to leave your site in order to get the programs installed.
NetShow and Its Loss Tolerant JPEG Codec
NetShow Version 1.0 and higher support JPEG (Joint Photographic Experts Group) images. In addition, NetShow contains a loss-tolerant (LT) JPEG image format.
Loss of data during transmission is common on the Internet. The NetShow LT JPEG codec allows JPEG images encoded using NetShow tools to be rendered on the client system even when significant packet loss has occurred during transmission. The NetShow JPEG codecs are non-VCM codecs. The NetShow LT JPEG format is currently available only through the NetShow ASF Editor and the NetShow Player.
For more advanced information about codecs, see List of Codecs That Ship With NetShow 2.0 and
Advanced Codec Information.
For up to date information on NetShow codec issues, see
http://www.microsoft.com/netshow/codecs.htm.
If you are developing an ACM or VCM codec or
other compression technology and are interested
in building a NetShow-based solution, please
e-mail
us.
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