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Microsoft Windows Logo Program System and Device Requirements  —  164

All MPEG-2 decoders can accept an MPEG-2 Elementary Stream. The DVD decoder must correctly handle subpicture properties and other functions. The minidriver for the subpicture decoder must be able to:

Set the subpicture properties.

Turn the subpicture compositing on and off.

Set the highlight rect parameters.

See B11.1.4.4; B11.1.1.3

B11.1.4.3 Device installation requirements
B11.1.4.4 MPEG and video component requirements

General Notes:

Examples of video sources are NTSC at 720 × 480 × 29.97 frames per second (fps) and PAL at 720 × 576 × 25 fps, both at MPEG 4:2:2. These resolution and frame rates are the standard definition. Other resolution and frame rate combinations may be subject to the same requirements, depending on the source, but only if the source resolution does not exceed the overall pixel rate of the above example (approximately 10.5 megapixels per second).

Video sources with higher pixel rates may cause system performance to degrade. Either dropped frames or reduced image quality, or a combination of both, become acceptable in that case. In the case of time-shifted playback, a slight relaxation is also acceptable. Combined reduction in image quality and frame rate should be commensurate with the excess in input data rate. For example, if the input data rate exceeds the standard definition pixel rate by a factor of four, acceptable performance could allow dropping half of all frames and image quality that is equivalent to having been high-quality scaled by a factor of two horizontally.

Notice that deinterlacing results in twice the display data rate when compared to the source data rate. However, de-interlacing by itself must never be the cause for frame rate or image quality reduction. Only increases in source resolution beyond this standard definition produce a relaxing of the video quality requirements.

The following solutions are exceptions to the basic video quality requirement:

Solutions serviced by nonisochronous video sources (Internet)

Video functions for monitoring purposes only and not for recreational viewing, such as monitor video windows (outputs) of video editing solutions.

B11.  On desktop system, TV-style MPEG-2 video stream playback consumes appropriate bandwidth.

For desktop system, TV-style MPEG-2 video stream playback consumes no more than an additional 45 percent of processor cycles.

B11. All MPEG-2 decoders can accept an MPEG-2 elementary stream.

DirectShow provides the selection and demultiplexing of MPEG transport streams and program streams. Stream filtering in hardware can be used to aid this process. DirectShow feeds the appropriate video stream, such as Elementary Stream, to the MPEG decoder. The decoder must be able to take MPEG in that form. Packetized Elementary Stream (PES) format support is also required without reliance on any packet sequence numbering. Decoders must not rely on packet sequence numbering to support applications where packet sequence numbers cannot be created. For example, audio and video might come from separate sources, such as video from disc being synchronized to

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