Case Study - Baseball

With all the Major League Baseball™ teams using edgertronic high speed video cameras for sports performance optimization, the edgertronic camera is an obvious choice. Once you see the video quality for yourself, you will wonder how we can do it at as an affordable price.

Here are some articles on the impact of high speed cameras used in baseball:

• From Trackman to Edgertronic to Rapsodo, the Tech Boom Is Fundamentally Altering Baseball
• Baseball America - High-Speed Cameras Spread Quickly Around Baseball
• Article at the Sport Techie website

Major league, college, and high school baseball teams have asked for high speed video camera purchase guidance and deployment procedures, which is provided below.

Camera selection

For baseball pitching training, scouting and coaching, the SC1+ Monochrome 16GB is the best choice. Let's look at the rationale behind this:

• The SC1+ is more than fast enough. Human muscles just don't move that fast, so 500-1000 frames/sec is fast enough to see what's happening in a pitch.

• Monochrome cameras produce a slightly sharper image and require 1/4 as much light as a color camera. There are other tradeoffs you might want to consider when making the color versus monochrome choice.

• The 16GB internal buffer gives you enough record time to capture all the pitches in a half inning.

Lens selection

There are a lot of different use scenarios, each with it's own lens recommendation:

Indoor cages and labs, where the camera is close to the pitcher, will require a wide angle lens. Here's a 14mm lens that works well: https://www.bhphotovideo.com/c/product/859173-REG/Samyang_SY14MAE_N_14mm_f_2_8_Super_Wide.html

For bullpen settings, a medium zoom like the following is useful: https://www.bhphotovideo.com/c/product/124669-USA/Nikon_1986_AF_Zoom_Nikkor_80_200mm_f_2_8D.html. In some settings, the supplied 50mm lens will work.

For centerfield shots, over the pitcher's shoulder toward home plate, you'll need a lens in the 400-600mm range. The most cost effective way to do this is buy a Nikon 300mm f2.8 EDIF lens ($800-1200 used) and pair it with a Nikon TC201 2X tele-extender ($50-100 used).

Lighting

Indoor training center lighting

High speed cameras, operating at high frame rates, require bright, flicker free lighting. This is true of all high speed cameras, not just the edgertronic.

High frame rates require shorter exposure times than typical cameras. As a result, lighting that works fine at 30 fps is probably not going to be sufficient at 1000 fps or higher.

For best results, you'll need at least 3000 lux illumination on the athlete. You might be able to live with less, but more is better and we think 3000 is a reasonable target.

Additionally, typical lights will have 120 Hz flicker (2x the 60 Hz AC power line). Human eyes can't see the flicker, nor can a camera taking a 30 fps video. Once the frame rate is high enough (60 fps and above) you'll see the flicker in your recorder videos.

There are no practical lighting solutions that are 100% flicker free and get you to the 3000 lux goal above. You can, however, get close enough that the flicker isn't objectional. We recommend no more that 5% flicker, DC to 10KHz. Once again you might be able to relax the requirement a little, but this is our recommendation.

SD Card Technology

All flash based storage devices (SSD, USB thumb drives, SD cards) have two dirty little secrets:

First off, every time you write the device, the transistors in the chips are damaged just a little. Do this enough and the data can't be stored reliably. This is called Write Endurance and is a measure of how many times you can erase and write the full device.

The second, even dirtier secret, is that the problem is getting worse. Flash devices are getting larger and cheaper at the expense of write endurance. 20 years ago write endurance was typically 100,000 to 1,000,000 cycles. Now, commercial SD cards have a write endurance around 300 cycles. This means after you've written 9.6TB to a 32GB card (300 x 32GB), it's done.

Heavy use scenarios like baseball, can exceed this limit in 1-2 years. For cameras mounted in remote locations or otherwise can't easily be accessed to swap out SD cards, we recommend industrial grade cards with a write endurance of at least 3000 cycles such as https://www.digikey.com/en/products/detail/delkin-devices-inc/SE32FSTL2-3B000-3/16909674

Camera control

Controlling the camera can be as simple as connecting the remote trigger, triggering the camera, and then latter copying the video and metadata files off the SD card. This would be a good approach for pitcher training outside, where the edgertronic camera can be on a tripod near the pitcher and the coach is triggering the camera.

-- or --

Controlling the camera can mean controlling several cameras, mounted around the stadium, using CAMAPI to configure, simultaneously trigger, and automatically download videos into a game data application.

The following sections discuss how various camera features can be used to integrate an edgertronic high speed camera into your baseball training and game day work flow.

Focusing and exposure

Both focus and exposure are done manually, at the camera. This means the camera needs to be accessible, not ideal in a stadium mounted configuration.

A typical approach for stadium mounted cameras is to set the focus once, and tape the lens so the focus ring can not move. Similarly, the exposure ring is set for the darkest lighting situation. Once set, the software ISO setting is modified as the lighting conditions change.

The edgertronic camera can be enhanced to control accessories. We are looking into supporting remote focus and exposure

Managing video files

There are two approaches - using network attached storage (or your server) to hold the video and metadata files or save the video files to the camera's SD card, then transfer and delete them.

CIFS network storage

The edgertronic camera supports CIFS network storage. It is an experimental feature (mainly because of the security issues associated with network storage). You can use traditional network attached storage (NAS), or configure a Windows, Mac, or Linux computer to support the CIFS server protocol.

The advantage when using CIFS network storage is you don't wear out the SD card in the camera, and perhaps to remove a file copy from your system solution. The disadvantage of using CIFS network storage is you may find the system less reliable, such as when a computer operating system does a periodic update and security features you disabled are enabled without your knowledge as part of the update, causing a future save of a captured video to fail.

Save to SD card then transfer

SD cards have a finite write life. If you are first saving to the camera's SD card, then you should consider replacing the SD cards on a regular basis if the camera is difficult to access. Also use a high reliability card (one that supports MLC or pMLC technology) such as the Micron Industrial SD cards.

You can use various protocols to download the video and metadata files. Supported file transfer protocols include HTTP, FTP, and WebDAV, with HTTP being the fastest and likely the easiest to use.

The general workflow would be:

• Configure the camera using CAMAPI run(requested_settings) where the requested_settings include setting save mode to background.
• Trigger the camera using CAMAPI trigger(filenname) where for this example the filename is assumed to be game_4_inning_7_top_pitch_4.
• Monitor when the video is saved by periodically fetching CAMAPI get_camstatus() checking the video_save_count to detect a change in value indicating another video was successfully saved.
• Fetch the video file using http://10.11.12.13/static/mnt/sdcard/DCIM/game_4_inning_7_top_pitch_4.mov and http://10.11.12.13/static/mnt/sdcard/DCIM/game_4_inning_7_top_pitch_4.txt. During development, you can browse to http://10.11.12.13/static/mnt/sdcard/DCIM to see a list of all video and metadata files available.
• Erase the video file and metadata file using CAMAPI erase_file("game_4_inning_7_top_pitch_4.*") where the .* means match both the mov and txt extensions.