CCTV Analysis and Court Presentation Material

Train CCTVCCTV Analysis

Following an Affray at a railway station CCTV images from the station and an on board train system were used by the prosecution in the form of a DVD compilation. We were instructed by one of the defence teams to analyse the CCTV evidence and clarify images containing their client for presentation in court.

Having viewed the DVD compilation disclosed to the defence we identified that the original Digital CCTV images had been converted to the DVD format. This can introduce artefacts, reduce edge detail and sometimes even miss out recorded frames. (see more here and here) so we advised that a copy of the original material should be requested so that we could carry out our analysis on the best evidence.

We identified that the timestamp used by both systems was not synchronised which made relating what could be seen from each system difficult and possibly misleading and produced material to identify the difference.  We produced clarified video and a document containing all of the relevant video images as stills in pdf format with the position of their client highlighted.

“At one stage in the proceedings, it [the pdf document] was referred to as the ‘bible’.”


After the completion of the trial the instructing solicitor said;
“The stills were very useful in terms of the on board footage and both other defence counsel said that this allowed them to explore points which they would otherwise not have been able to. At one stage in the proceedings, it [the pdf document] was referred to as the ‘bible’. Thank you as ever for your sterling work – and turnaround. I know that I always find the way in which the material is sent very useful and easy to access / use in terms of presentation (despite my lack of computer know how). Thanks again for your hard work!”
G. Bell of The Purkiss Partnership

We can help you!

If you have a case involving Audio, Digital Image or Video Evidence then please either call or click the button

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Save time by using a Forensic Video Analyst

Save time by using a Forensic Video Analyst

Is it worthwhile spending time reviewing CCTV evidence that may, if misunderstood, lead you down the wrong path? [Tweet this]

Hopefully your answer to that was no.

In the case of CCTV evidence it may prove a waste of time and effort to assume that the material disclosed is all of the material, is unbiased and in an appropriate format. You may also be missing an opportunity to examine all of the material.

A couple of short examples to illustrate why you might want to get a Forensic Video Analyst to review the CCTV evidence before you expend a lot of effort and possibly come to the wrong conclusion…..

‘Gesture’ by murder victim

A legal professional reviewed video evidence and thought that they could see the victim gesture towards the accused after the alleged assault which lead to his death. I won’t go into the relevance of the gesture but they repeatedly viewed the images provided to them and eventually became convinced of what they thought the images showed.

They came to us to clarify the images and to explore how they could easily show this  ‘Gesture’ to the court.

Firstly the images that had been provided to them had been converted to the DVD video format so we requested a copy of the original digital CCTV. We then examined that and found that the recording only contained six images per second from the relevant camera. The individual was in the distance, it was night time although the street lamps were on and he was wearing a dark long sleeve top. Analysis of the CCTV images before and after the one image were the ‘Gesture’ was seen showed that there were dark areas in the background that made it appear that the person raised their arms in that single frame as they moved along the pavement and across the dark areas in the background.


The CCTV images did not provide any evidence to support the ‘Gesture’ but an awful lot of their time had been spent on it.

Friend reviews evidence of theft

Three years ago an employee was accused by their employers of theft, the company carried out their own investigation which included seizing the relevant images from the locations digital CCTV system. They then made a complaint to the police and provided them with their findings and the original CCTV exhibit, the person was arrested and subsequently charged. The prosecution served a disc containing the video evidence together with other papers supporting their case.

The accused appointed a solicitor and the case progressed, a friend of the accused agreed to assist them by analysing the material including the video evidence.

The friend set about examining the material in detail. The video material was on a DVD without a menu and the video played continuously, the video showed the accused at the location going about their daily routine moving from one camera view to another. But then he noticed that the sequence didn’t make sense, some time periods were missing, some images had a time stamp but some didn’t. He thought that there was something sinister going on. [Tweet this]

Through the solicitor a request was made to the court for the original CCTV. Having been told that the prosecution had already served everything they were eventually supplied with another DVD. This had a navigation menu and what appeared to be 12 separate clips of video. Again a lengthy examination of the discs contents were made and compared against the original disc.

It was discovered that some new material had been added but some images that existed on the fist disc were not on the second. The content of both discs appeared to the friend to have been edited to provide a skewed and biased record of events and that there was, he believed, a conspiracy between the employers and police to prove their case.

Many adjournments later and with a week to go to the next trial date we received a phone call from the friend. They asked if we could help to make sense of the material and provide a professional opinion on what had taken place.

Our expert CCTV analysis quickly identified that neither disc was a copy of the original material produced by the internal investigator although the police stated that they had not edited the content.

In reality both discs simply contained an edited version of the original recording converted to the DVD video format, albeit they were produced with a bias towards the prosecution’s case.


Any further attempt to analyse the content of the images should have been made against the original recording.

The accused, the friend and the legal professionals could have saved a lot of time/money by asking an expert to review the material at the outset. [Tweet this]



Has the CCTV video evidence been converted to DVD-VIDEO?


Video tape recording converted to DVD-Video

It appears to have become common practice to convert CCTV video evidence to the DVD-Video format.

Why should Solicitors and courts care?

Our CCTV Analysis has shown that there can be issues with the quality of the conversion of the original material to DVD-Video in respect of image quality and it not always being a faithful representation of all the originally  recorded images.

Apart from the quality and veracity of the content it is unlikely that the Compilation DVD will  contain all of the material seized and you may possess information that requires additional images to be viewed.

See my previous article on the problems with using the DVD-Video format for evidential material. Click here

What to look for.

Here are some indicators to help you tell if the CCTV evidence has been re-formatted to the DVD-Video format;

  • The disc may be identified with an easy to see DVD-R or DVD+R text or logo, not a definitive test but enough to suggest that the material needs further examination.

    DVD+R disc

    Look for disc markings

  • When you insert the DVD into your computer either a window opens with options to play the DVD using one of your installed software players or one of those players automatically opens.
    pop up window when disc inserted

    Pop up window


  • Once the software player is open you may see a menu which might provide some information about the content of the video and who created it. The menu will also contain text or small thumbnails which act as buttons that allow you to select which video to play. Some DVD-videos do not have a menu and the video images play straightaway. – See more at:

    DVD Menu Screens

    Selection of DVD menu screens

  • With the video playing there are likely to be visual clues such as;
    • There might be a wide border, typically black, around the video.
    • The images may show the video playing in another player that you are unable to control.
    • The camera view may change suddenly indicating that the video may have been created as a compilation of views to show the images that best support the editors point.
    • Some of the text around the image such as the date and time may be blurred, imagine what the conversion has done to the image detail.
  • Using your computer explore the contents of the disc in the same way you would folders on your hard drive, if you find a folder entitled VIDEO_TS and it contains files with the extensions .IFO, .BUP & .VOB you have a DVD-Video.

What to do next?

If you want to ensure that you have all of the recorded images at the best possible quality and the CCTV system uses a Digital Video Recorder (DVR) you should request a bit for bit copy of the original material or if the system is tape based you will require access to the original master video tape recording.

Or if you prefer you can send the material to us together with copies of relevant case papers and we will carry out an Initial Assessment and provide a report on its suitability for analysis or as a format for presenting the evidence.


There’s more to this than meets the eye…..

This is a topic which I covered in a previous blog post that I have resurrected as it is as true today as when I wrote it two years ago.

There is a problem in the Criminal Justice system which relates to how best to present/disclose video evidence.

On the one hand everyone wants an easy  method of displaying the video to the court when required and with the least fuss. So in many cases the material is converted and authored to DVD. But should we be interested in the quality of that video; how faithfully does it represent the recorded images or can we say that it doesn’t matter as the material is only to provide an overview. If we want to ensure that the court can understand specific details in the video then we will need to use the best version of the recording. This probably wont be the DVD.

What about a Forensic CCTV Analysis of that material? We would want to be sure that what we examine is a true copy of the original recording not a compressed version of it.

Here’s a previous article from a couple of years ago that highlights a part of this,

Document thumbnail




There’s more to this than meets the eye



Video Evidence – Why won’t all DVDs work in your DVD player?

close up of discThis post is not intended as a technical document but more a help page for those that deal with audio and video evidence that is now more frequently found on a disc rather than a tape.  Many police forces now habitually convert analogue and digital video material to DVD-Video but may also serve the material to defence solicitors as copies of the original data disc, this post should help you to understand the differences between the two types of disc format and allow you to view the material.

Lets start with what a DVD is so we all know where we’re starting from.

First:What does DVD stand for?

If I was on the television program QI I’d hold up the “Nobody Knows” placard, DVD is one of those acronyms that has passed into our vocabulary but for which nobody seems to be able to agree on the meaning. The people who first developed the format used Digital Video Disc but the DVD Forum decided it should be Digital Versatile Disc but later decided that as the meaning couldn’t be agreed on and  ‘DVD’ was an international standard then the three letters were exactly that, just letters. So although it does seem a bit strange it is correct to refer to a disc as a ‘DVD disc’.

What is it?

DVD is a format for storing data on a disc with the same physical size as a Compact Disc but has the capacity to hold a minimum of 4.7GB of data. Commercially created discs are referred to as DVR-Rom (Read Only Memory) and can not be written to or altered. Writable discs, DVD-R (DVD dash R) and DVD+R (DVD plus R) store data in a similar way as that used to create a Compact Disc (CD) and can be read by an optical laser and converted by hardware and software into a format that can be viewed and/or heard. A writable disc can be termed as Write Once/ Read Many (WORM) or Re Writable (RW). The +R and +RW format are not recognised by the DVD Forum but are supported by the DVD+RW Alliance.

Discs containing audio and/or video evidence should be of the WORM type to prevent data being deleted or added.

Formats and duplicating

So we’ve established that DVD is an optical storage medium, but the next issue is that there are many variations of DVD formats, the most popular WORM formats are DVD-R and DVD+R with DVD-RW,  DVD+RW and DVD-RAM being Re -Writable formats. You are most likely to come across DVD-R and DVD+R discs, the difference between the formats is more relevant to the Re-Writable versions of these formats and are not relevant to this discussion. If you want to duplicate a disc you will need to use the same format of disc. Discs can contain up to 4.7 GB of data there are also Dual Layer  (DL) single sided discs available which have a capacity of 8.5GB which also need a specific type of disc for copying. There are also double sided single layer and double sided dual layer discs but these are very rarely used.

Playing the discs

The main difference that will effect end users is whether the disc contains data or DVD-video.

DVD Data

If the disc contains data exported from a Digital Video Recorder (DVR) it is often exported to a disc, depending on the amount of data then this could be a CD or a DVD. This disc will not play in a set top DVD player, a PS3 or xBox 360 but can be accessed using a computer which has a DVD drive. To view the video files you may need to install the proprietary software player which should be included on the disc.

The disc may alternatively contain other types of data and/or audio and video files that can be viewed on a computer using software such as Windows Media Player or Quicktime.


DVD Video Logo

The content of these discs can be viewed using most modern set top DVD players or a games machine such as a PS3 as well as your computer providing it has a DVD drive and software that is capable of playing DVDs. The content may be structured with a menu or may simply just play the video contained on the disc.


Putting a disc into the DVD drive.Some new DVD players are capable of playing discs containing just image files and there are other defects or recording problems that may cause a DVD-Video disc not to play in your DVD player.

One reason that the DVD wont work in your DVD player is that it contains data and your player is expecting it to have DVD-Video, so before sending the disc back as defective you may want to try it in your computer first.


If you have any questions about audio and video evidence contained on CD or DVD discs or other aspects of audio and video evidence please call or use the contact form (Contact Us) to request a call back.

Next time

In my next post I will talk more about how the fabled non destructible disc is in fact very fragile, despite what Raymond Baxtor said about it in 1981 on Tomorrows World (yes I am that old)..