Video analysis: where do I start?
Issue: Volume 28 Number 2
Video analysis, once considered a tool only for the biomechanist or high-performance coach, is now becoming a technology used by many coaches working with athletes of all ages and standards. As discussed by Keith Lyons (2003a, 2003b), there has been an enormous growth in video-analysis software, which has allowed the coach to improve their qualitative technical and performance analyses to their athletes. However, for many coaches, particularly the majority who may not be IT savvy, video analysis may appear threatening rather than friendly. Moreover, the technology may be more detailed than one might think to get started. The aim of this article is to discuss some of the details that coaches need when considering the use of video analysis.
Video analysis software
Table 1 illustrates examples of technique-analysis software programs currently available. These programs essentially capture video, edit, compare and allow for graphical overlays (Lyons 2003). However, each program has its own variations on how these components work, including up to four comparison windows and in some programs blending of one video over another for more exact comparison. Some software (for example, Dartfish) comes in different ‘packages’, known as ‘multi-model’, that have specific (or extra) components such as Simulcam TM (superimposing one athletic performance over another) or StroMotion TM (breaking down an athletic movement frame-by-frame). Basic programs do not have these specific components, so for coaches experienced with video analysis, multi-model software is recommended (it is cheaper and gives greater coaching flexibility in the long run).
However, for coaches starting out in this area, the questions that should be asked are ‘For what essential purpose will I be using the video?’ and ‘Will I use these extra capabilities on a regular basis?’ As the saying goes, ‘use it or lose it’; if you do not use a component of the program, chances are you will forget how to do so, creating needless delays and frustrations — for both you and your athletes.
Table 1: Current technique-analysis software programs available
|DV Coach TM||US||PC|
|Silicon Coach TM||NZ||PC|
|Sports Coach TM||UK||PC|
One of the decisions you have to make relates to ensuring the analysis software will work on your computer. There are two types of computer hardware system available on the market:
- IBM compatible (PC)
- Apple Macintosh.
Most software is made for PC, which operates using Windows (2000 or XP platforms); however only one analysis system uses the Apple (OSX platform).
Modern computers have the capacity to run video analysis programs, but coaches need to be aware that with updates to these programs, computers may similarly need updating. Make sure that when speaking to a video analysis distributor you tell them what operating system your computer is running and, if possible, what type of processor your computer uses (for example, Pentium 4). Also, be aware of ‘minimum requirements’ versus ‘recommended requirements’, as this will also affect how efficiently analysis can occur.
If you are purchasing a computer, another decision to be made is whether you choose a desktop or a laptop (portable) computer. For functionality and versatility, a laptop would be preferable in coaching. More recently, hand-sized pocket PCs, once little more than electronic diaries, are now rapidly catching up to laptops in processing capabilities (however, memory capacity, and important consideration for storage, is still lacking). With laptops and pocket PCs being transportable, the coach can capture and show the video to the athlete during the practice session. Knowledge of performance is beneficial when the athlete observes and evaluates their performance (Magill 2003).
Digital video cameras are essential in video analysis, and with the technology being so prevalent, digital video cameras are now relatively inexpensive. Your camera must be able to interface with the computer, so make sure you also have a video capture card and fire wire cable to feed into the computer.
Consider whether you will set up the camera in a fixed position (on a tripod) or operate it by hand. In most cases having a fixed camera position is preferable, as it allows for an aspect of the technique to be fully observed and analysed (such as the foot plant during running cycle). Further, it allows you to coach at the same time as you are analysing (for example, coaching and analysing a tennis backhand stroke). A good software package should have a functional remote controller that allows freedom of movement and coaching while the video records (you can place the tripod where normally you would be standing). Of course, not all sports analyses can be effectively conducted with a fixed camera; sometimes the coach needs to see the whole skill performed, not just one part of it.
The positioning of the camera is also important. Most analyses are conducted from the side, but similar to coaching, observation must come from different angles, so make sure you position the camera at various angles to capture all movements (even on non-dominant sides for asymmetrical sports such as the racket sports). For coaches who are fortunate enough to obtain two cameras, some software programs are able to take dual-incoming feeds that provide simultaneous observation from different angles.
The coach should also be aware of environmental influences. Consider the direction of sunlight, shadows from trees or buildings; or if indoors, how to compensate for the lower levels of light. For sports played on sprung floors, movement from the athletes can give the camera the ‘jitters’, affecting the quality of the capture.
Standardising the analysis
Analysis is only beneficial if standardised comparisons can be made. It is not uncommon for coaches to use comparisons of young athletes to current champions. Although they are well meaning, there are many aspects of such comparisons that are not standardised, particularly in reference to that particular moment in the event or match. Further, camera placement is unlikely to be in the exact same place, which also influences the analysis.
Standardising the analysis does not have to be complicated. Aim to try and utilise the same area each time. Use reference markers such as cones and, if possible, have some previous data loaded into the software program to compare reference points.
Storing the data
Finally, coaches need to think about where to store their data. As mentioned above, it is important to consider memory space. Table 2 outlines data storage terminology and average memory costs of a typical video clip.
Do not get into the habit of ‘hording’ clips; even if you have a computer with the largest hard disk it will not take long before it is filled. If you are a coach who likes to keep every clip, transfer these onto a CD (cheap but limited in space) or an external hard disk (plenty of space, but another expense). Regardless of your choice of data storage, transferring your files can serve as a back up if the unthinkable happens and you computer crashes!
Table 2: Hard disk memory storage terminologies and typical video clip memory costs
|Term||Definition / conversion|
|Byte (single unit of information)||Measure of data storage equalling eight bits|
|Kilobyte (KB)||Equals 1000 bits|
|Megabyte (MB)||Equals 1000 kilobytes|
|Gigabyte (GB)||Equals 1000 megabytes|
|Audio Visual Interleave (AVI)||Video file format|
Examples: 18MB AVI video clip = Approximately eight seconds
One rugby match will require five to eight GB of storage
Video analysis is a technology that assists the coach in observing an athlete’s technique and providing feedback. However, just like any technology, the potential can only be realised if the coach knows what they need and how to use it. Some video-analysis software dealers run introductory courses, as do state sporting organisations. These courses and workshops will save you time and possible frustration, and will benefit your athletes.
Lyons, K 2003a, ‘Technique analysis’, Sports Coach, 25(4), pp. 22–3.
Lyons, K 2003b, ‘Performance analysis for coaches’, Sports Coach, 26(1), pp. 30–1.
Magill, RA 2004, Motor Learning and Control: concepts and applications, 7th edn, McGraw Hill, Boston.