IAMWstDecoder interface (iwstdec.h)
[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 It has been superseded by MediaPlayer, IMFMediaEngine, and Audio/Video Capture in Media Foundation.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 IAMWstDecoder interface sets and retrieves information about World Standard Teletext (WST). The WST Decoder filter implements this interface.
Inheritance
The IAMWstDecoder interface inherits from the IUnknown interface. IAMWstDecoder also has these types of members:
Methods
The IAMWstDecoder interface has these methods.
| IAMWstDecoder::GetAnswerMode Downstream filters use the GetAnswerMode method to retrieve the current answer mode. |
| IAMWstDecoder::GetBackgroundColor Downstream filters use the GetBackgroundColor method to retrieve the current physical color used in color keying the background for overlay mixing. |
| IAMWstDecoder::GetCurrentPage Downstream filters use the GetCurrentPage method to retrieve the current WST page. |
| IAMWstDecoder::GetCurrentService Applications use the GetCurrentService method to retrieve the current WST service. |
| IAMWstDecoder::GetDecoderLevel Applications use the GetDecoderLevel method to retrieve the WST decoder level. This method is not implemented and always returns AM_WST_LEVEL_1_5. |
| IAMWstDecoder::GetDrawBackgroundMode Downstream filters use the GetDrawBackgroundMode method to determine whether the caption text background is opaque or transparent. |
| IAMWstDecoder::GetHoldPage Downstream filters use the GetHoldPage method to determine whether the current WST page is held. When the WST decoder holds a page, any updates from the TV stream are turned off. It is though the page was paused in real time. |
| IAMWstDecoder::GetOutputFormat Downstream filters use the GetOutputFormat method to retrieve the size, bit depth, and other parameters of the output video. |
| IAMWstDecoder::GetRedrawAlways Downstream filters use the GetRedrawAlways method to retrieve a value that indicates whether the whole output bitmap is redrawn for each sample. |
| IAMWstDecoder::GetServiceState Applications use the GetServiceState method to retrieve the current service state. |
| IAMWstDecoder::SetAnswerMode Downstream filters use the SetAnswerMode method to assign the current answer mode. |
| IAMWstDecoder::SetBackgroundColor Downstream filters use the SetBackgroundColor method to assign the physical color to be used in color keying the background for overlay mixing. |
| IAMWstDecoder::SetCurrentPage Downstream filters use the SetCurrentPage method to assign the current page. |
| IAMWstDecoder::SetDrawBackgroundMode Downstream filters use the SetDrawBackgroundMode method to assign whether the caption text background is to be opaque or transparent. |
| IAMWstDecoder::SetHoldPage Downstream filters use the SetHoldPage method to tell the WST decoder to hold the current WST page. When the WST decoder holds a page, any updates from the TV stream are turned off. It is as though the page was paused in real time. |
| IAMWstDecoder::SetOutputFormat Downstream filters use the SetOutputFormat method to define an output video format. |
| IAMWstDecoder::SetRedrawAlways Downstream filters use the SetRedrawAlways method to determine whether the whole output bitmap should be redrawn for each sample. |
| IAMWstDecoder::SetServiceState Applications use the SetServiceState method to assign the service state. |
Requirements
| Requirement | Value |
|---|---|
| Minimum supported client | Windows XP [desktop apps only] |
| Minimum supported server | Windows Server 2003 [desktop apps only] |
| Target Platform | Windows |
| Header | iwstdec.h |