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3.7.5.100 Vr

LabTalk Object Type:

The vr object reads a video file and imports frame (or frames) of video to matrix object/matrixbook.

Methods:

Method	Description
*vr.Open(fname)*	Open a video with the specified file name (include the complete file path) Return value: 0: successful. Other values: failure and the value is the standard error code.
*vr.SeekFrame(frameOffset, nOrigin)*	Move the pointer associated with the video to a new location that is framesOffset frames from nOrigin. nOrigin values: -1: the first frame of the video 0: default value. The current frame 1: the last frame of the video
*vr.SeekTime(msecOffset, nOrigin)*	Move the pointer associated with the video to a frame that locates msecOffset milliseconds after nOrigin. nOrigin values -1: the beginning of the video 0: default value. The current time 1: the end of the video
*vr.ReadFrame([dataset])*	Import a frame to the specified dataset. If the dataset is not given then the active one is used.
*vr.ReadFrame(MBookName, layerIndex, objectIndex)*	Import a frame to the specified matrix object [MBookName]LayerIndex!"ojectIndex".
*vr.ReadFrames(MBookName, frameCount, skipFrames)*	Import frameCount frames to the first matrixsheet of MBookName, skipping every skipFrames frames. Each frame is imported into a matrix object.
vr.Close( )	Close the video. Return value: 0: successful. 1: failure.

Properties:

All Vr properties are read-only.

Property	Access	Description
Vr.FourCC	Read only numeric	A number corresponding to the video's four character code.
Vr.FourCC$	Read only string	Four character code used to identify the video codec.
Vr.Format	Read only numeric	OpenCV format code. See below Channel properties for extracted info: Channels: number of channels per frame ChannelBits: bits per channel ChannelInt: channel data integer values ChannelSigned: channel data signed values Note: the format and channel properties are based on the lastly read frame.
Vr.Channels	Read only numeric	Number of channels per frame
Vr.ChannelBits	Read only numeric	Bits per channel
Vr.ChannelInt	Read only numeric	Channel data integer values
Vr.ChannelSigned	Read only numeric	Channel data signed values
Vr.FPS	Read only numeric	Frames per second
Vr.FrameCount	Read only numeric	Number of frames in the video file
Vr.Width	Read only numeric	Video width in pixels
Vr.Height	Read only numeric	Video height in pixels
Vr.PosFrames	Read only numeric	Current position in frame
Vr.PosMSec	Read only numeric	Current position in millisecond

Examples:

This script shows how to import 1 out of every 15 frames into the active matrixbook, each frame to a matrix object.

string vfilename$ = "C:\test.mp4";
int StepSize = 15; // skip every 15 frames

int err = vr.Open(%(vfilename$));// Open the video file.
if( 0 == err )
{
	int TotalFrames = vr.FrameCount/StepSize;
 
	// Read from beginning to the end of the file into matrix.
	vr.ReadFrames(%h, TotalFrames, StepSize);
	vr.Close();// Close the video file.
};

There is also a full example of how to import 100 frames from a video into a new matrixbook.