Windows 7 Media Platform

Media Foundation and DirectShow® provide the basis for media support in Windows. Media Foundation was introduced in Windows Vista as the replacement for DirectShow. In Windows 7, Media Foundation has been enhanced to provide better format support, including MPEG-4, as well as support for video capture devices and hardware codecs.

Format Support
In Windows 7, Media Foundation provides extensive format support that includes codecs for H.264 video, MJPEG, and MP3; new sources for MP4, 3GP, MPEG2-TS, and AVI; and new file sinks for MP4, 3GP, and MP3. In addition, a new DirectShow wrapper source provides a bridge between DirectShow and Media Foundation. With it, a Media Foundation application can play older media formats that lack native Media Foundation support.

Hardware Devices
Media Foundation now supports the following types of hardware devices in the audio/video pipeline:
• UVC 1.1 video capture devices, such as webcams
• Audio capture devices
• Hardware encoders and decoders
• Hardware video processors, such as color-space converters

Hardware codecs can perform very fast video transcoding. For example, suppose you want to transfer a Windows Media Video (WMV) file to a cell phone that supports only 3GP files. With a hardware encoder, the file can be transcoded "as needed," immediately before transferring it to the device. Hardware codecs also provide a more secure environment for implementing content protection schemes, so that premium content can be viewed on the PC. Hardware devices are represented in Media Foundation by a proxy object, and are used in the pipeline just like software-based components.

Simplified Programming Model
In Windows Vista, Media Foundation exposed a relatively low-level set of APIs. These APIs are flexible, but may not be appropriate for performing tasks. Windows 7 adds new high-level APIs that make it simpler to write media applications in C++. These new high-level APIs include:
• MFPlay. These APIs are designed for audio and video playback. They support the typical playback operations (stop, pause, play, seek, rate control, audio volume, and so forth), while hiding the details of the lowlevel APIs (the session and topology layers).

• Source Reader. You can use these APIs to pull raw or decoded data from a media file, without knowing anything about the underlying format. For example, you can get a thumbnail bitmap from a video file or get live video frames from a webcam.

• Sink Writer. You can use these APIs to author media files by passing in uncompressed or encoded data. For example, you can re-encode or remix a video file.

• Transcode. The Transcode APIs target the most common audio and video encoding scenarios.

Platform Improvements
Windows 7 includes numerous enhancements to the underlying Media Foundation platform APIs. Advanced applications can use these APIs directly; other applications will get the benefits indirectly. These benefits include:

• Improvements in the video pipeline to reduce power consumption and video memory usage.

• New DVXA video processing APIs, which use a more flexible compositing model and are better suited for HD video formats.

• Improvements to the way in which plug-ins (sources and decoders) are
enumerated and managed.

Source of Information : Guia Windows 7 Developer Guide


Subscribe to Developer Techno ?
Enter your email address:

Delivered by FeedBurner