Knowledge Base

H.264 AVC Video Format

H264 AVC in MP42 container, with extension *.mp4, is the format of video created by EthoVision XT 16-18 and MediaRecorder 5 and 6.

Video Files Created by EthoVision XT

When you record video with EthoVision XT, video is encoded with the H.264/MPEG-4 AVC codec and is stored in a container of MP4-version 2 (MP42). The video file extension is mp4.

Note that a container is something different from the codec.

• The container is the structure that handles various streams such as video and audio streams. You can imagine the container as a box that contains your video frames.
• The codec is software that compresses the video stream data.

Video Files Created by Media Recorder

MediaRecorder 4.0

• With analog cameras: H.264 AVC in an MPG container.
• With GigE cameras: MPEG-4 Video in an MP4-version 2 container.
• With IP cameras: H.264 stream in an MP4-version 2 container.

MediaRecorder 5.0

• With all cameras: H.264 stream in an MP4-version 2 container.

MediaRecorder 6.5

• With all cameras: H.264 stream in an MP4-version 2 container.

All video files have file extension mp4.

Video Formats Not Supported by EthoVision XT

Important: The term "not supported" means that the video formats listed below were not thoroughly tested by Noldus. It may be that some formats work fine. If you have old MPEG-2 videos and you want to re-track them with EthoVision XT, test them and check whether (1) video plays smooth and without artifacts ("blocks" in the image) and (2) samples are not missed during tracking, even when selecting the Detection Determines Speed (DDS) option.

Important: When using camcorders or other encoding software to make video files, test those files in EthoVision XT before deciding to work with them or convert them to a supported format.

• MPEG-1.
• MPEG-2. This is a collection of formats; not all may work in EthoVision XT.
• DivX.
• Variants of MPEG-4. However, an AVI 1.0 file with codec MP43, and an OpenDML AVI file with codec MP4S-ISO MPEG-4 Video V1 may work.
• DV-AVI. This is uncompressed video from FireWire cameras. This format is not recommended because of the large file size. DV-AVI is a special case of AVI. In general, EthoVision XT does not support video files of AVI format. The AVI format should not be confused with the file extension avi.
• WMV. However, an OpenDML AVI file with codec WMP v9 may work.
• QuickTime.
• FLV (Flash video, YouTube).
• XviD variants of the MPEG-4 format. However, an OpenDML AVI file with codec XviD 1.0 RC4 may work.

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.
• 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.
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.

The following table can be used as a reference for video created with EthoVision XT. 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. The amount of movement in the video also influences file size — the more movement, the larger the resulting video file. Therefore, the size of your video files may differ from what is reported below, even when using a comparable setup.

Tips for Color Tracking