Datastead TVideoGrabber SDK

Detects if a video signal is present.

Declaration
function IsVideoSignalDetected (DetectConnexantBlueScreen: Boolean; DetectCustomRGB: Boolean; CustomR, CustomG, CustomB: LongInt; UseAsMaxValues: Boolean): Boolean;

bool __fastcall IsVideoSignalDetected (bool DetectConnexantBlueScreen, bool DetectCustomRGB, int CustomR, int CustomG, int CustomB, bool UseAsMaxValues)

Function IsVideoSignalDetected (DetectConnexantBlueScreen as Boolean; DetectCustomRGB as Boolean, CustomR as Long, CustomG as Long, CustomB as Long, UseAsMaxValues as Boolean) as Boolean

Description

Used to detect if a video signal is present.

It returns:
- true if a video signal is detected,
- false if a blue screen or dark screen is detected (see below).

This function can act in 2 ways, depending of the DetectConnexantBlueScreen and DetectCustomRGB parameters (that can be combined):

DetectConnexantBlueScreen is enabled:
The "classical blue screen" of video capture boards including Connexant video chips, that corresponds to "no video signal" is detected (in this case the function will return false)

DetectCustomRGB is enabled:
The CustomR, CustomG and CustomB parameters specify the values of the colors used to detect if a video signal is present, according to the UseAsMaxValues parameter:
UseAsMaxValues is disabled:
The video signal will be reported as "not detected" if all the pixels tested on the video frames have the exact RGB values specified in CustomR, CustomG and CustomB.
UseAsMaxValues is enabled:
The video signal will be reported as "not detected" if all the pixels tested on the video frames have a lower value than the CustomR, CustomG and CustomB values specified.

E.g:

Connexant (BT8x8) cards:
IsVideoSignalDetected (true, false, 0, 0, 0, false) returns false when the blue screen of Conexant BT8x8 based cards is detected.

Techwell cards:
IsVideoSignalDetected (false, true, 16, 16, 16, false) returns false when the black screen of Techwell cards is detected.

Conexant as well as Techwell cards
IsVideoSignalDetected (true, true, 16, 16, 16, false) returns false when either the Conexant's blue screen or the Techwell's black screen is detected.

True black video
IsVideoSignalDetected (false, true, 0, 0, 0, false) returns false on a really black video (all RGB values = 0)

Detection of a dark ambient light
IsVideoSignalDetected (false, true, 30, 30, 30, true) returns false on a dark or black video (all RGB values below 30)