# First create videos in MediaRecorder and then track from video file in EthoVision XT

## Aim

To create videos that can be used for tracking in EthoVision XT.

## Prerequisite

You have cameras that are supported for tracking in EthoVision XT.

## Procedure

1. Create videos in MediaRecorder.
2. In EthoVision XT, select **Track from video file** and select the video. See the EthoVision XT Help for details.

## Notes

- **<span class="FM_All_caps">IMPORTANT </span>** In theory you can create video files from many different digital cameras with MediaRecorder. However, the quality of the digital camera is essential for accurate tracking. If you use other hardware or cameras than the supported ones, you need to check whether the time information in the video files is correct.

See [Test an unsupported setup](https://bookstack.noldus.com/link/395#bkmrk-page-title) in [Specifications](https://bookstack.noldus.com/link/390#bkmrk-page-title)

- When you use analog cameras, you must adjust the aspect ratio. For digital cameras that are not supported this may also be necessary.

See see [Adjust the video aspect ratio (analog cameras only)](https://bookstack.noldus.com/link/457#bkmrk-page-title)

- Choose **EthoVision** as the **Output Quality** if you record from four cameras simultaneously. With the default settings two cameras are recorded on CPU and two on the video card (GPU). This results in differences in file size. By selecting **EthoVision** as the output quality, all four cameras will be recorded using CPU power. For more information see [Output settings](https://bookstack.noldus.com/link/423#bkmrk-output-settings).
- Choose **DanioVision** as the **Output Quality** if you film DanioVison larvae. With this setting the compression of the video files is limited to have an optimal video quality to detect the small larvae. The file size will be larger than with the default **Output Quality** setting.