http://blog.csdn.net/zhaobisha/archive/2008/08/01/2752622.aspx
我们已经跨入了对高清数字媒体时代。未来的数字高清将无处不在。但是他非常需要健壮的保护，而这是当前的数字媒体平台所不具备的。Media Fundation就是为了这个而存在。
让我们审视高清数字，这个平台需要很有弹性，便于从小故障下恢复。需要考虑大量的不同品质的video 和audio.Media Foundation就是为了这个而存在。比如，支持下一代的HD技术：
1：DirectX 视频加速(DXVA) 2.0提供了比DXVA1.0更高效率的视频加速，更稳定，最新的视频解码能力，和扩展的硬件视频加速。在DXVA2.0下，windows可以直接处理某些高清内容，并容易错误恢复。
2：Color-space能得以保存在整个视频处理流程中，所以中途可以无转换损失，用户可以享受到高逼真的画质。这个也能减少CPU等消耗。
3：增强的视频渲染器（enchanced video render EVR)增强了视频处理和时钟等。
让我们研究一下文件保护，在用户购买了一部电影之后，他可以把电影传到他的某个设备上（一些设备支持直接在播放的时候录制），这个过程中会有多种保护模式，购买后的使用保护，播放时防录制保护，复制保护，如果某一个保护没有正确完成，就会使整套保护没有了意义。所以这需要有一个无缝的平台去相互协作。Media Foundation就是为了这个而存在。
最后，让我们来总览一下DirectShow. DirectShow的API对这些数字高清媒体的应用程序确实是非常通用的，万能的，但是，DirectShow作为一个10多年的老技术而言已经力不从心了。比如：
1：流程是静态static的，所以实现动态的Graph和Major format change是非常困难的。
2：DirectShow filter的线程模型是非常复杂的，要完全理解并永不出错是太困难了。
3：DirectShow filter只能用于DirectShow。
4：DirectShow不支持文件保护。
作为DirectShow的接替者，Media Foundation出现了，他不会马上替代DirectShow,作为第一步，他将在vista上慢慢展露他的影响。
但是目前为止，Media Foundation只能在媒体保护（Proteced media process)）方面大施手脚,还未向DirectShow进行足够的扩展和替代。
Appendix: Feature Comparisons
The following table compares the features of Media Foundation with those of DirectShow.
Feature
group Feature Media
Foundation DirectShow
Basic functionality Audio and video rendering Yes Yes
Event notification Yes Yes
Device enumeration No Yes
Component enumeration Yes Yes
Synchronization to reference clock Yes Yes
Seeking Yes Yes
Improved stress resilience Yes No
Content protection Component validation Yes No
Content protection policy negotiation Yes No
Interoperability between content protection technologies Yes No
Protection against kernel-mode and user-mode threats Yes No
Component revocation and renewal Yes No
Video output protection management Yes Yes
Media tasks Audio capture No Yes
Video capture No Yes
Video editing No Yes
DVD playback and navigation No Yes
MPEG-2 support No Yes
ASF support No Yes
TV technologies No Yes
Stream buffer engine No Yes
Encoder API No Yes
Video renderer Substream mixing using per-pixel or planar alpha blending Yes Yes
Customizable video composition No Yes
Support for custom presenters Yes Yes
Windowless rendering Yes Yes
Multimonitor support Yes Yes
DXVA Yes Yes
DirectDraw exclusive mode Yes Yes
Backward compatibility with existing applications Yes Yes
Accurate frame stepping Yes Yes
Alpha blending of image data Yes Yes
Glitch resilience Yes No
Enhanced video fidelity Yes No
Enhanced content protection robustness Yes No
Standalone use Yes No
Standalone mixing component Yes No
Transforms (MFT or DMO) Synchronous data processing Yes Yes
Simple programming model Yes Yes
Standalone use Yes Yes
Multiple inputs and multiple outputs Yes Yes
Dynamic number of streams Yes No
Access to sample-level metadata Yes No
In-place processing Yes Yes
Dynamic format changes Yes No
Quality adjustment Yes No
Rate change Yes No
The following table compares the features of Media Foundation with those of the Windows Media Format SDK.
Feature
group Feature Media
Foundation Format SDK
ASF file features Audio and video streams Yes Yes
Image streams No Yes
Arbitrary streams (text, file, Web, custom data) No Yes
Script commands No Yes
Data unit extensions Yes Yes
SMPTE time code support No Yes
Mutual exclusion Yes Yes
Stream prioritization Yes Yes
Bandwidth sharing No Yes
Indexes Yes Yes
Markers Yes Yes
Multiple bit rate stream Yes Yes
Multiple language support Yes Yes
Codec features CBR encoding Yes Yes
VBR encoding Yes Yes
Two-pass encoding Yes Yes
High-resolution audio support Yes Yes
Low delay audio Yes Yes
S/PDIF audio output Yes Yes
Video image Yes Yes
Device conformance template Yes Yes
Video complexity settings Yes Yes
Frame interpolation Yes Yes
DirectX Video Acceleration Yes Yes
File writing Video resizing Yes Yes
Color space conversion Yes Yes
Audio resampling Yes Yes
ASF file sink Yes Yes
Network sinks No Yes
Push sinks No Yes
Watermarking support No Yes
Input formats, input settings, and data unit extensions Yes Yes
WMA smart recompression No Yes
Multichannel audio Yes Yes
File reading User-allocated sample support No Yes
Synchronous reading No Yes
Output format enumeration Yes Yes
Multichannel audio Yes Yes
MP3 support Yes Yes
Network sources Yes Yes
Metadata ID3 support No Yes
Custom metadata Yes Yes
Digital rights management Live DRM No Yes
DRM Individualization Yes Yes
Back up and restore DRM licenses Yes Yes
View DRM attributes in the Metadata Editor Yes Yes
Output protection levels Yes Yes
License revocation Yes Yes
Windows Media DRM for Network Devices Yes Yes
Secure Audio Path No Yes
Playlist burning Yes Yes
Third-party transcription support Yes No
Local license issuance Yes No
Enhanced Windows Media DRM renewability Yes No