|Subject: Forensic video analysis Sun Feb 26, 2012 11:59 pm|| |
Forensic video analysis is the scientific examination, comparison and/or evaluation of video in legal matters.
Listed below are common techniques that are required of forensic video analysts.
- Reliably digitize video tape footage onto a computer system. (This is commonly done via Non-Linear Editor (NLE) software.)
- Be able to demultiplex or separate camera views from multiplexed CCTV footage.
- Convert digital video from DVR (Digital Video Recorder) devices into digital video formats usable for forensic analysis.
- Perform clarification techniques such as frame averaging.
Highlight someone or something of interest in the video.
- Enlarge portions of the video for areas of interest.
- Measure heights of individuals or distances between points seen in the video.
Standard Operating Procedures (SOPs)
A written, documented set of Standard Operating Procedures (SOPs) should be established to outline the procedures that the analysts are expected to follow during the course of reviewing forensic video evidence. Listed below are items to consider when writing SOP's.
EquipmentAlthough at one time S-VHS VCRs were considered state-of-the-art, today these tape based recording devices are mostly retired from use. Much more important for doing forensic video analysis is a computer editing system and specialized forensic software. Many of these software programs are quite advanced, and the knowledge to operate them is crucial.A tape based VCR that will play back older formats such as S-VHS, 8 mm and Hi8 decks are also recommended, but these older systems can be rented if the need arises.Another piece of equipment that is no longer needed is an external Time Base Corrector (TBC). At one time this was crucial to doing forensic video work, but newer digital security camera systems make this absolete.A video monitor capable of displaying the underscan and overscan area of a video signal.A forensic video analysis system capable of digitizing analog video in an uncompressed, format.A professional quality printer from creating court evidence to be used in jury trials is nice, but also not necessary. Best practice is to buy a basic printer for draft printing of images, and then go to a professional photo lab to have high quality enlargements made ready for use in court.
- This must be done so that it adheres to the standards of evidence and so it is admissible in a court of law.
- They must follow the proper Chain of Custody with that evidence.
- Special precautions must be taken to ensure that the evidence is properly protected and stored. In the case of analog video tapes, the record tab should be removed and for digital video it should be write protected.
- Considerations for peer review of casework should be made.
- Ongoing training should be included and planned. Through professional organizations such as American Academy of Forensic Science, IAI, NATIA, LEVA, local community college courses and also vendor specific training.