CCrossbar Class
The CCrossbar class controls video crossbars. The crossbar filter is modeled after a general switching matrix, with n inputs and m outputs. Any of the input signals can be routed to one or more of the outputs.
This class creates a single object that encapsulates all connected crossbars. CCrossbar enumerates all unique inputs that can be reached from a given starting pin and automatically routes audio when a video source is selected.
CCrossbar supports an arbitrarily complex graph of crossbar filters. These filters can be layered and can contain dead inputs and outputs. CCrossbar can enumerate all the possible inputs and select a single input for recording and viewing.
Given a starting input pin (typically the analog video input to the capture filter), this class recursively traces upstream searching for all viable inputs. An input is considered viable if it is a video pin and is either unconnected or is connected to a filter that does not support the IAMCrossbar interface.
CCrossbar Constructs a CCrossbar object. GetInputCount Retrieves the number of unique video inputs that can be selected. GetInputIndex Retrieves the currently selected input. GetInputName Retrieves a human-readable string describing the type of each input. GetInputType Retrieves the computer-readable physical type of each input. SetInputIndex Selects a particular input.
CCrossbar::CCrossbar
Constructs a CCrossbar object.
Syntax
CCrossbar(
IPin *pPin);
Parameters
- pPin
- Pointer to starting input pin.
Return Value
No return value.
CCrossbar::GetInputCount
Retrieves the number of unique video inputs that can be selected.
Syntax
HRESULT GetInputCount(
LONG *pCount);
Parameters
- pCount
- Pointer to the number of video inputs.
Return Value
Returns S_OK.
CCrossbar::GetInputIndex
Retrieves the currently selected input.
Syntax
HRESULT GetInputIndex(
LONG *Index);
Parameters
- Index
- Pointer to current routing index.
Return Value
Returns S_OK.
CCrossbar::GetInputName
Retrieves a human-readable string describing the type of each input.
Syntax
HRESULT GetInputName(
LONG Index,
TCHAR *pName,
LONG NameSize);
Parameters
- Index
- Current routing index.
- pName
- Pointer to the buffer that will receive the text version of the current routing input. It cannot be equal to NULL before the method call or the operation will fail. For example, if the current routing input is of type PhysConn_Video_Tuner, the function will return the string "Video Tuner" in this parameter. For more information, see Remarks.
- NameSize
- Size of the buffer that will receive the text version of the current routing input. Note that the buffer pointed to by pName must be large enough to include a terminating null character.
Return Value
If the buffer is large enough to copy the string name, the method returns S_OK; otherwise, the method returns E_FAIL.
Remarks
The following table shows what the pName parameter returns, depending on the current routing type.
Physical type pName PhysConn_Video_Tuner Video Tuner PhysConn_Video_Composite Video Composite PhysConn_Video_SVideo Video SVideo PhysConn_Video_RGB Video RGB PhysConn_Video_YRYBY Video YRYBY PhysConn_Video_SerialDigital Video SerialDigital PhysConn_Video_ParallelDigital Video ParallelDigital PhysConn_Video_SCSI Video SCSI PhysConn_Video_AUX Video AUX PhysConn_Video_1394 Video 1394 PhysConn_Video_USB Video USB PhysConn_Video_VideoDecoder Video Decoder PhysConn_Video_VideoEncoder Video Encoder PhysConn_Audio_Tuner Audio Tuner PhysConn_Audio_Line Audio Line PhysConn_Audio_Mic Audio Mic PhysConn_Audio_AESDigital Audio AESDigital PhysConn_Audio_SPDIFDigital Audio SPDIFDigital PhysConn_Audio_SCSI Audio SCSI PhysConn_Audio_AUX Audio AUX PhysConn_Audio_1394 Audio 1394 PhysConn_Audio_USB Audio USB PhysConn_Audio_AudioDecoder Audio Decoder
CCrossbar::GetInputType
Retrieves the computer-readable physical type of each input.
Syntax
HRESULT GetInputType(
LONG Index,
LONG *PhysicalType);
Parameters
- Index
- Current routing index.
- PhysicalType
- Pointer to the physical type of pin (video). Returns a member of the PhysicalConnectorType enumerated data type.
Return Value
Returns E_FAIL if the Index parameter is out of bounds; otherwise, returns S_OK.
CCrossbar::SetInputIndex
Selects a particular input.
Syntax
HRESULT SetInputIndex(
LONG Index);
Parameters
- Index
- Routing index to be set.
Return Value
Returns S_OK if successful; otherwise, returns E_FAIL.
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