StartSequenceCapture (DVR version only)
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Description

Starts acquiring a sequence of frames into the memory. Use StopSequenceCapture to end the sequence capture process.


Syntax


[VB]
objActiveUSB.StartSequenceCapture Frames [, Timelapse = 0 ]

[C/C++]
HRESULT StartSequenceCapture( long Frames, float Timelapse);



Data Types [VB]

Frames : Long
Timelapse : Single (optional)

Parameters
[C/C++]

Frames [in]  
The number of frames to capture.  
Frames>0 - sequence capture will stop automatically after the specified number of frames is reached, unless StopSequenceCapture is called before that.  
Frames<0 - loop recording mode; when the specified number of frames is reached, the capture will continue in a loop until StopSequenceCapture is called.  
Timelapse [in]  
The interval between consecutive frame acquisitions in seconds. If zero or not specified, the sequence will be captured at the current frame rate.  


Return Values


S_OK  
Success  
E_FAIL  
Failure.  
E_INVALIDARG  
Invalid file name.  


Example


This VB example demonstrates how to capture the video loop into the system memory at the current frame rate. The maximum sequence size is set to 1000 frames:

Private Sub
StartButton_Click()
ActiveUSB1.StartSequenceCapture -1000

End Sub


Private Sub
StopButton_Click()
ActiveUSB1.StopSequenceCapture

End Sub



Remarks

It is recommended to use CreateSequence for memory allocation before calling StartSequenceCapture. If CreateSequence was not called or did not allocate enough memory, StartSequenceCapture will have to reserve the necessary amount of memory itself, which will introduce a delay between the function call and actual start of the sequence capture.

During the sequence capture the FrameRecorded event will be fired per each frame recorded into the memory.

In the loop recording mode (Frames < 0) after the frame limit is reached, ActiveUSB will maintain the specified number of recorded frames in the memory by removing a frame from the head of the sequence and adding the latest frame to its tail. Thus, in the example above, at any given moment the sequence will contain the most recent 1000 frames.

To reduce the memory consumption, ActiveUSB records frames in a sequence in the original raw image format. When the sequence is played back, its frames are converted to a regular monochrome or RGB format on the fly. See PlayVideo for more details.

If Timelapse is not specified, the sequence will be recorded at the maximum frame rate defined by the camera settings and system throughput.