Microsoft DirectX 8.0

Line 21 Decoder Filter

The Line 21 Decoder filter accepts line21 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 line21 data provider, e.g., a DVD video decoder that has a line21 data output pin, or the CC Decoder WDM filter (via KsProxy) that provides line21 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.)

The following diagram shows a typical DVD filter graph using the Line 21 Decoder.

DVD Filter Graph Using Line21 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
Category CLSID_LegacyAmFilterCategory