Encoding Feature Requirements

The following table provides information about the Windows Media Encoder features that have specific Windows Media Player, operating system, or codec requirements.

Encoder Feature	Player Version	Operating System	Codecs
Interlaced output video	Windows Media Player 9 Series	Windows XP	Windows Media Video 9
Nonsquare pixel output	Windows Media Player 9 Series
Multiple-resolution MBR content	Windows Media Player 9 Series
MBR audio	Windows Media Player 9 Series
DRM support	Windows Media Player 6.4 and later
Multichannel audio	Windows Media Player 9 Series	Windows XP	Windows Media Audio 9 Professional or Windows Media Audio 9 Lossless
High-resolution audio (24-bit,96 kHz)1	Windows Media Player 9 Series	Windows XP	Windows Media Audio 9 Professional
Dynamic range control	Windows Media Player 9 Series	Windows XP Professional	Windows Media Audio 9
CBR encoding (one-or two-pass)	Windows Media Player 6.4 or later		See the following table
Quality-based VBR	Windows Media Player 7.1 or later		See the following table
Bit rate-based VBR	Windows Media Player 7.1 or later		See the following table
Peak bit rate-based VBR	Windows Media Player 7.1 or later		See the following table

¹ Earlier players or operating systems will render 16-bit, 48-kHz content

Understanding the Buffer

“Buffering” is a dirty word in the streaming media business. While buffering is a necessary evil in streaming, it is often confused with the concept of delay.

Buffering refers to the time during which Windows Media Player receives and stores data(“filling the buffer”), but before it can start rendering the content. The Fast Start and Fast Cache features of Windows Media Services greatly improve the end-user experience by minimizing the time it takes to fill the Player buffer.

“Delay” refers to amount of time it takes for a frame to be captured, encoded, and then rendered on the Player. Current technology does not allow you to stream content in real time with less than a 2-second delay. But there are a few adjustments you can make to the encoder, server, and Player to reduce the amount of delay by a few seconds end-to-end.

• On the server running Windows Media Services, select the appropriate broadcast publishing point, click the Properties tab, click Networking, right-click Enable buffering, and then click Disable.

• In Windows Media Player, click the Tools menu, and then click Options. Click the Performance tab, click Buffer, and then type the number of seconds to use for buffering.

• In Windows Media Encoder, click Properties, click the Compression tab, and then click Edit. Click the tab containing the bit rate for which you will adjust the buffer, such as 282 Kbps. In Buffer size, type the number of seconds to use for buffering. This number indicates the amount of time content will be stored before encoding begins. It also represents the amount of time that the Player will lag behind the encoder during a broadcast.

  Note that these adjustments could lower playback quality and performance.

Note that content encoded with the Windows Media Audio and Video 9 codecs (except for the Windows Media Audio 9 codec) is not supported in Windows Media Player version 6.4. For Windows Media Player version 7.1 and Windows Media Player for Windows XP, content encoded with any of the codecs requires users to download the codec before playback. Content encoded using VBR encoding with the Windows Media Audio 9 codec may have glitches or silence during playback in Windows Media Player version 6.4. For Windows Media Player version 7.1 and Windows Media Player for Windows XP, content encoded with the Windows Media Audio 9 codec does not require a user to download the codec.

The following table lists the supported encoding methods for the codecs that are included with the encoder.

Codec	One-pass CBR	Two-pass CBR	Quality-based VBR	Bit rate-based VBR	Peak bit rate-based VBR
Windows Media Audio 9 Professional	Yes	Yes	Yes	Yes	Yes
Windows Media Audio 9 Lossless	No	No	Yes	No	No
Windows Media Audio 9	Yes	Yes	Yes1	Yes1	Yes1
Windows Media Audio 9 Voice	Yes	No	No	No	No
Windows Media Video 9	Yes	Yes	Yes	Yes	Yes
Windows Media Video 8.1	Yes	Yes	Yes	Yes	Yes
Windows Media Video 7	Yes	Yes	Yes	Yes	Yes
Windows Media Video 9 Screen	Yes	No	Yes	No	No

¹ Some glitches or silence may occur during playback in Windows Media Player version 6.4.