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[The feature associated with this page, DirectShow, is a legacy feature. It has been superseded by MediaPlayer, IMFMediaEngine, and Audio/Video Capture in Media Foundation. Those features have been optimized for Windows 10 and Windows 11. Microsoft strongly recommends that new code use MediaPlayer, IMFMediaEngine and Audio/Video Capture in Media Foundation instead of DirectShow, when possible. Microsoft suggests that existing code that uses the legacy APIs be rewritten to use the new APIs if possible.]
The GetDecoderLevel method retrieves the closed-captioned decoder level.
Syntax
HRESULT GetDecoderLevel(
  AM_LINE21_CCLEVEL *lpLevel
);
Parameters
lpLevel
Pointer to a variable that receives a member of the AM_LINE21_CCLEVEL enumeration. The returned value is always AM_L21_CCLEVEL_TC2 (TeleCaption II).
Return value
Returns an HRESULT value. Possible values include the following.
| Return code | Description | 
|---|---|
  | 
Invalid argument | 
  | 
Success | 
Remarks
TeleCaption I and TeleCaption II are standards for closed caption decoders. The Line 21 Decoder filter supports TeleCaption II, which is backward compatible with TeleCaption I.
Requirements
| Requirement | Value | 
|---|---|
| Minimum supported client | Windows 2000 Professional [desktop apps only] | 
| Minimum supported server | Windows 2000 Server [desktop apps only] | 
| Target Platform | Windows | 
| Header | il21dec.h | 
| Library | Strmiids.lib |