Microsoft DirectX 8.1 (C++)

Line 21 Decoder Filter

The Line 21 Decoder filter is used in filter graphs running on Microsoft® Windows® 9.x and Windows 2000 platforms. On Microsoft Windows XP Home Edition and Windows XP Professional, the Line 21 Decoder 2 filter is used whenever the Video Mixing Renderer is in the graph.

This filter accepts line 21 data in either the standard byte pair format or, in the case of DVD, as a packet for the whole group of pictures (GOP). For every GOP in the DVD video stream, there can be a user data packet that has that particular GOP's header information and line 21 data.

On the input pin the filter connects to any line 21 data provider, e.g., a DVD video decoder that has a line 21 data output pin, or the CC Decoder WDM filter (via KsProxy) that provides line 21 data from the VBI stream coming into a TVTuner/video capture card.

The filter decodes the line 21 data into bitmaps and passes them to the downstream filter, either to a secondary pin on the Overlay Mixer or to the Video Renderer. (The Overlay Mixer's primary pin always takes the main video stream.)

See DVD Filter Graph Configuration for a diagram that shows a typical DVD filter graph using the Line 21 Decoder.

Filter Interfaces IAMLine21Decoder
Input Pin Media Types Major Type: MEDIATYPE_AUXLine21Data
Subtype:
  • MEDIASUBTYPE_Line21_BytePair [standard line 21]
  • MEDIASUBTYPE_Line21_GOPPacket [DVD line 21]

    Format Type: FORMAT_VideoInfo or none.

Input Pin Interfaces None.
Output Pin Media Types Major type: MEDIATYPE_Video
Subtype:
  • MEDIASUBTYPE_RGB8
  • MEDIASUBTYPE_RGB555
  • MEDIASUBTYPE_RGB565
  • MEDIASUBTYPE_RGB24
  • MEDIASUBTYPE_RGB32

    Format Type: FORMAT_VideoInfo

Output Pin Interfaces None.
Filter CLSID CLSID_Line21Decoder
Property Page CLSID None
Executable qdvd.dll
Merit MERIT_NORMAL
Filter Category CLSID_LegacyAmFilterCategory