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ICaptionServiceDescriptor Interface

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Microsoft DirectShow 9.0

ICaptionServiceDescriptor Interface

This topic applies to Update Rollup 2 for Microsoft Windows XP Media Center Edition 2005 and later.

The ICaptionServiceDescriptor interface enables the client to get caption service descriptors from a Program and System Information Protocol (PSIP) table in an ATSC stream. The content advisor descriptor may be present in the event information table (EIT). For more information, refer to ATSC Standard A/65B, Program and System Information Protocol for Terrestrial Broadcast and Cable (Revision B).

In addition to the methods inherited from IUnknown, the ICaptionServiceDescriptor interface exposes the following methods.

Method Description
GetCaptionServiceNumber Returns the Service Number for a specified caption service.
GetCCType Queries whether a caption service contains Digital Television Closed Captioning (DTVCC) or line-21 closed captioning.
GetEasyReader Queries whether a caption service contains "Easy Reader" captions.
GetLanguageCode Returns the language code for a specified caption service.
GetNumberOfServices Returns the number of caption services.
GetWideAspectRatio Queries whether a caption service is formatted for wide-screen displays.

Remarks

To obtain a pointer to this interface, do the following:

  1. Call IAtscPsipParser::GetEIT to get the IATSC_EIT interface.
  2. Call IATSC_EIT::GetRecordDescriptorByTag and pass in the caption service descriptor tag (0x86). If the descriptor is present, the method returns an IGenericDescriptor pointer.
  3. Query the returned IGenericDescriptor pointer for the ICaptionServiceDescriptor interface.

Requirements

Header: Include atscpsipparser.h.

See Also