Analog Television

Microsoft DirectShow 9.0

Analog Television

Analog television differs from other video capture scenarios in several ways:

• The tuner card tunes to an analog signal, which is then digitized.
• Audio is carried in the analog signal. How the audio reaches the sound card varies depending on the hardware.
• The signal may contain additional data in the vertical blanking interval (VBI), such as closed captions (CC), World Standard Teletext (WST), and extended data services (XDS).

The following diagram shows a typical filter graph for television preview:

• The TV Tuner filter controls tuning.
• The TV Audio filter controls the audio decoding.
• If the tuner card has more than one physical input, the Analog Video Crossbar filter enables the application to select which input is decoded and rendered.
• The WDM Video Capture filter delivers the digitized video stream.

The Capture Graph Builder automatically inserts any filters that are required upstream from the capture filter.

This section contains the following topics:

• Analog Television Tuning
• Analog Television Audio
• Closed Captions and Teletext

See Also

• Video Capture