# Record digital video

Background

Digital video requires a lot of storage capacity and always needs to be compressed before it can be stored on a disk medium. In order to compress a video recording you need an encoder, usually a plug-in board, which converts the video signal into a media file on disk at a fraction of the original size. The input signal can either be analog or digital.

Prerequisites

▪If you have analog cameras: EthoVision XT works with the Picolo Alert encoder board. You can use this board not only for live tracking, but also for recording video. See Install analog cameras

▪If you have digital cameras:

▪Install GigE cameras

▪Install USB 3.0 cameras

Another possibility is to use the Noldus MediaRecorder software to make digital video files and track from these videos in EthoVision XT (offline tracking).

Procedure

1.Create a new experiment or open an existing one.

2.In the Experiment Settings, select the camera(s). See Video source

3.In the Arena Settings, calibrate and draw the arena.

4.In the Acquisition screen, on the right-hand pane select Save video only, track later. With this option you record the live image to a video file without tracking. Select this option especially if your computer is not fast enough to do tracking and recording at the same time. For other options, see Acquire Data in this Help.

5.To start recording, click the Start trial button.

tip Save this experiment as a template (File > Save As). You can then re-use the same settings in a new experiment when you Create a new experiment based on an existing experiment.

Video file location

Your video files are saved in the Media Files subfolder of your experiment folder. By default in: C:\Users\Public\Public Documents\Noldus\EthoVision XT\Experiments\ [experiment name]\Media Files.

Video file size

Roughly speaking, the file size is given by:

File size = Bitrate x Duration x Compression ratio

Where:

▪The Bitrate is the product of Frame size x Frame rate (frames per second)

▪The Duration is the length of the video (in seconds).

▪The Compression ratio tells how much space is needed to store similar frames that have fewer moving parts, like an empty open field.

You can use the following table as a reference for video created with EthoVision XT. Please note that the figures reported are only indicative. There are other factors which influence video file size, such as whether a variable bit rate is used or which color space is used. Also the amount of movement in the video influences file size. The more movement, the larger the resulting video file.

Therefore, the size of your video files may well differ from what reported here below, even when using a comparable setup.

Resolution, frame rate | Camera | 10 minutes video | Duration per GB
1280x1024, 30 fps | Basler GigE, monochrome | 75 -150 MB | 1-2 h
1280x1024, 25 fps | Basler GigE, color | 175 MB | < 1 h
2560x1024, 10 fps | Basler GigE, color | 100-160 MB | 1-2 h
720 x 480, 30 fps | Analog cameras, monochrome | 60 MB | 16 h
DanioVision 800x600, 60 fps | Basler GigE, monochrome | 90-125 MB | 1-1.5 h
DanioVision 1280x960, 25 fps | Basler GigE, monochrome | 355 MB | < 30 min

See also

▪Video file formats