P

PAL

Analog composite color television standard, with a rate of 25 frames per second, and 50 fields per second. Much of Europe, Australia, and other parts of the world use PAL. See also NTSC and SECAM.

pan-scan

DVD-Video display format in which a 16 × 9 video is cropped for display in a 4 × 3 window, using parameters defined by the video author. See DVD_PREFERRED_DISPLAY_MODE.

parser filter

A filter that pulls information from a disk by using the asynchronous file reader filter, or from the Internet by using the URL moniker filter.

performance build

A build that adds performance measurement capabilities to a retail build.

periodic advise

A regular series of advise calls.

pin

A COM object created by the filter that represents a point of connection for a data stream on the filter. Pins provide interfaces to connect with other pins and transport data. Input pins accept data into the filter, and output pins provide data to other filters. An input pin typically exposes the IPin and IMemInputPin interfaces. An output pin typically exposes the IPin, IMediaSeeking, and IQualityControl interfaces. A source filter provides one output pin for each stream of data in the file. A typical transform filter, such as a compression/decompression (codec) filter, provides one input pin and one output pin.

plug-in distributor

A COM object that exposes a particular control interface and implements it by calling the enumerator of the filter graph manager, finding which filters expose the control interface and communicating directly with those filters. The developer generally doesn't implement these interfaces directly.

preroll

The queuing of data in advance of the desired playback time or position. Preroll improves the accuracy of playback and recording. For example, the initial audio data within AVI files is often loaded in advance of the first video data to help synchronize the video and audio data. DirectShow filters often preroll data so they are ready to play immediately. Prerolling is also important in video editing and device control, because VCRs typically position the tape to a given "preroll" distance from the point at which to record or playback so that the recording or playback occurs cleanly.

preroll time

Preroll time is the time prior to the start position at which nonrandom access devices should start rolling. See preroll.

presentation time

The stream time at which the packets of data that a filter receives should be presented downstream or rendered. When a filter graph runs, each filter is passed a start time according to the reference clock, and the packets of data that a filter receives will usually be time-stamped with the presentation time.

preview section

The portion of the filter graph from the capture filter's preview pin downstream to and including the video renderer.

primary surface

The area in memory containing the image being displayed on the monitor. In Microsoft DirectX®, the primary surface is represented by the primary DirectDrawSurface object.

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