July 2015 – Exacq

Overview

This is a legacy document for those with ExacqVision Desktop Client 7.6 and earlier. It has been superseded by Article 14544.

If video is exported that contains some relevant content but also contains content that should not be distributed due to privacy concerns, it is possible to crop the exported video to specific dimensions that will exclude non-relevant parts of the scene.
This process is performed outside of exacqVision using free and commonly available applications. These instructions are written for Windows computers, however similar tools may exist for other operating systems.

Steps to crop video:

1. On the exacqVision Search Page find the video to export.
2. Right-click on the video panel and select Copy to Clipboard.
3. Open Microsoft Paint and paste in the screenshot (CTRL-V).
4. Ensure the “Rectangular Select” tool is highlighted.
5. Position the cursor at the upper-left corner of the area to keep. In the bottom left of MS Paint, write down the horizontal and vertical coordinates of the mouse.
6. Left-click-hold and drag the mouse to create a rectangular selection around the video to keep. In the bottom left, just to the right of the mouse location coordinates, write down the horizontal and vertical pixel size of the selection.
7. Close MS Paint.
8. Export the video in exacqVision as an .AVI video file.
9. Download and unzip the static build of the FFMPEG video converter program, available at http://ffmpeg.zeranoe.com/builds/, into a directory of your choice.
10. Move the video export to the \ffmpeg\bin\ directory where ffmepg was unzipped.
11. Open a Windows Command Prompt and navigate to the \FFMPEG\bin\ directory.
12. Execute the following command: ffmpeg -i -filter:v “crop=[width]:[height]:[horizontal start]:[vertical start]” [output.avi]

Use your actual values for these variables:
[export.avi] = the name of the video file exported from exacqVision. Note: If your file name has spaces in it, enclose the filename in quotation marks.
[width] = the horizontal pixel width written down in step 6.
[height] = the vertical pixel width written down in step 6.
[horizontal start] = the horizontal start position written down in step 5.
[vertical start] = the vertical start position written down in step 5.
[output.avi] = The name of the new cropped video file that will be created. Note: If your desired file name has spaces in it, enclose the filename in quotation marks.

For example, if the video to keep started in the upper left corner and was a size of 400×300, the command would be formatted as follows:

ffmpeg -i classroom4C_20150730_081900.avi -filter:v “crop=400:300:0:0” cropped_classroom_4C_20150730_081900.avi

With hard drive offerings only increasing in size, it is important to remember that some large increases in RAID Arrays may not be read correctly by Windows. This is because there are limits to the cluster size that different sizes of volumes can use. If the volume is expanded beyond a cluster size limit, it will become unreadable by the OS. Before expanding (or migrating) an array, please use the following table from microsoft of the limits of each volume size:

https://support.microsoft.com/en-us/kb/140365

Example: You have a 20-drive system from exacq that is half full of 4TB drives, the total capacity is 40TB. After RAID 6 creation, formatting and partitioning the array, we end up with a volume that is more like 30TB. Using NTFS, the OS will assign a cluster size of 8KB. Later down the road, you decide to fill the rest of the system with 4TB drives and migrate the array instead of making a new one. This will increase the capacity to roughly 70TB. The default cluster size for that volume would be 32KB, not 8KB. The array would become unreadable to the OS at this point and a reformat would need to happen. Reformatting a drive will erase all data stored within the volume.

Solution: To avoid losing data on the array, it is suggested to create a new array using the adding drives if it will push your capacity over the limit of the cluster size. Keep in mind that at least three drives are needed for a RAID 5 and that the total capacity of one drive will be used by the array’s parity. We suggest at least 9 drives be used before creating a RAID 6 array as the total capacity of two drives will be used by the array’s parity.

Best-Practice-for-Expanding-an-Array-Using-NTFS-Windows.pdf