Law Enforcement Application Questions

I'm just finishing up a CCTV system for a law enforcement interrogation room.

We're using a Toshiba DVR that's recording 2 cameras at 30 PPS each with a microphone assigned to each camera.

Recorded files can and will be used as evidence in criminal trials.

Questions are as follows:

There's a bit of a audio video sync problem with the lips not exacly matching the audio. I'm hoping that this doesn't prove to be a problem. Has anyone had any similar findings, and or solutions?

Question #2 regarding digital signatures. I've been informed by the county prosecutor that I will most likely be subpeonaed at some point as an expert withness when a defense attorney will test the validity of a digital CCTV file.

In their manual, Toshiba describes their proprietary files as being suitable for law enforcement applications as they are "extremely difficult to tamper with".

However, "extremely difficult" is not exactly the same as "impossible" is it?

The machine will also backup files as AVI's and assign digital signatures to them as well.

Does anyone know of a technical white paper on digital signatures when applied to AVI files that would be pertinent in this situation?

Anyone else do a similar type of application as this?

I'd be curious to see what type of equipment you used and how the results were.

This is obviously an extemely important project.

There is a company in Australia who manufacture an interview system, maybe you can get some information from them.

http://www.joincc.com.au/html/july05.html

The below may help? I've only been to court a few times and never been asked anything. Once the video is palyed the pert usually pleads........if it gets that far becasue the video is entered as evidence and if the perts lawyer is any good he/she would go for a plea agreement.

The chain of evidence is usually the most questioned. Is the DVR secured? Are the tapes secured? Who has keys or access? Is the clock/time/date correct? How do you verify the time/date? Was ther ay maintenance on the DVR equipment? Who did it? Have you done a background check on those persons/Company to ensure they are not fellons? How many copies were generated? Do you have a record of all copies issued? Is this the original tape/CD? How do I know that? Did you use water mark technology? If yes, can you explain it? Prove it is working? Same with the priority recording method of the DVR. There has to be an opportunity for tampering before they can challenge the validity of the tape. Most video supports the charges and other evidence presented so the issue of validating it is not that critical.

I'd look into attending some courses that support your cases. Make sure they are reputable and provide a certificate. If they put you on the stand to testify on "your" recording techniques will you have a solid chain of evidence and equipment maintenance?

And lastly, make some phone calls to other departments t talk the talk with those who have done what you are doing. I'd start at the DA and work my way down.

http://www.jhuapl.edu/ott/technologies/featuredtech/DVA/DVA.pdf

First of all, welcome to the group!

Don't know where you're from but there is good reading on interrogation/interview rooms at www.leva.org. Here you'll find Best Practices relating to video files and how they are to be processed in the event they are used in court.

The Toshiba DVR's usually make use of the MJPEG compression engine. JPEG is "lossy," meaning that the decompressed image isn't quite the same as the one you started with, however you can vary the degree of lossiness by adjusting compression parameters. Key is to keep the compression file size the largest possible. As it is an interrogation room, you won't be recording 24/7 so keep the quality to a maximum. Toshiba does have a Proprietary MJPEG which may cause you some grief down the road.

As far as the audio/video sync challenge, this might prove to be a problem. In working with forensics specialists, they recommended we install traditional VHS recorders (I know) and separate audiocassette recorders. We have started using DVD recorders which make use of MPEG2 compression engine which keeps audio/video in sync. Updating your AVI codecs might improve audio/video sync.

Regarding digital signatures, most likely you won't be subpoenaed at some point as an expert witness. Toshiba would have to contacted as their compression is proprietary. There are forensic video analysts like Grant Fredericks who are recognized and can be called upon to verify the validity of a digital CCTV file. The law enforcement should have procedures in place regarding continuity of evidence and other aspects of interrogation, so digital signatures are not that important.

AVI files would not be admissible in court as they are not the original file. They would be fine for defense or crown prosecutors to review, but there must be an original. We’re finding the police use the original recorder to playback the files. Can the Toshiba export to another medium? CD for example?

Just a few things to consider.

Rapid

The below may help? I've only been to court a few times and never been asked anything. Once the video is palyed the pert usually pleads........if it gets that far becasue the video is entered as evidence and if the perts lawyer is any good he/she would go for a plea agreement.

Thanks. That does look to be helpful. I'll study it and pass it on to the powers that be.

The chain of evidence is usually the most questioned. Is the DVR secured? Are the tapes secured? Who has keys or access? Is the clock/time/date correct? How do you verify the time/date? Was ther ay maintenance on the DVR equipment? Who did it? Have you done a background check on those persons/Company to ensure they are not fellons? How many copies were generated? Do you have a record of all copies issued? Is this the original tape/CD? How do I know that? Did you use water mark technology? If yes, can you explain it? Prove it is working? Same with the priority recording method of the DVR. There has to be an opportunity for tampering before they can challenge the validity of the tape. Most video supports the charges and other evidence presented so the issue of validating it is not that critical.

Yikes! Thanks for the warning.

I'd look into attending some courses that support your cases. Make sure they are reputable and provide a certificate. If they put you on the stand to testify on "your" recording techniques will you have a solid chain of evidence and equipment maintenance?

Are there any that you would suggest?

And lastly, make some phone calls to other departments t talk the talk with those who have done what you are doing. I'd start at the DA and work my way down.

None of the other departments are using digital yet. I'm working directly with the prosecutor's office, and this is new ground for all of them.

First of all, welcome to the group!

Thank you for the warm welcome!

Don't know where you're from but there is good reading on interrogation/interview rooms at www.leva.org. Here you'll find Best Practices relating to video files and how they are to be processed in the event they are used in court.

Excellent link. Thank you. I wasn't aware of that organization. BTW, I'm from Indiana.

The Toshiba DVR's usually make use of the MJPEG compression engine. JPEG is "lossy," meaning that the decompressed image isn't quite the same as the one you started with, however you can vary the degree of lossiness by adjusting compression parameters. Key is to keep the compression file size the largest possible. As it is an interrogation room, you won't be recording 24/7 so keep the quality to a maximum. Toshiba does have a Proprietary MJPEG which may cause you some grief down the road.

I'm recording 30 FPS at the highest quality setting.

As far as the audio/video sync challenge, this might prove to be a problem. In working with forensics specialists, they recommended we install traditional VHS recorders (I know) and separate audiocassette recorders. We have started using DVD recorders which make use of MPEG2 compression engine which keeps audio/video in sync. Updating your AVI codecs might improve audio/video sync.

The VHS thing is disheartening as that's exactly what we just replaced!

What bugs me is that for $400, you can buy a TIVO machine that records spectacularly, but a $7K professional DVR gives you choppy video and lousy audio sync. Doesn't make much sense does it?

AVI files would not be admissible in court as they are not the original file. They would be fine for defense or crown prosecutors to review, but there must be an original. We’re finding the police use the original recorder to playback the files. Can the Toshiba export to another medium? CD for example?

The situation is such that there are occasions when the judge will not allow certain portions of an interview to be used in court. In these occasions, it is neccessary for the department's forensic techs to take the original proprietary Toshiba file and export it in AVI format for editing.

The DVR does support AVI exporting, and it does embed a digital signature on the AVI file, but obviously, once the file has been edited, the digital signature is null and void.

For this reason, it is neccessary for them to always retain a copy of the original file to submit as proof that the AVI has not been tampered beyond removing the parts as ordered by the judge.

In other words, the edited AVI file would be presented to the jury while the original file would be entered into evidence.

I have alot of customer who install exactly what you are talking about and they are all different. One guy uses 8mm recording devices because according to him digital is not valid yet. Another guy uses DVD recorders with HD's (kinda like Tivo but with a DVD burner) and the rest use anything from PC Card system's to cheap OEM DVR's that they buy from some asian guy because I can't compete with those prices. Basically from what understand there are different laws on what can be used in court depending on where you are. The best way to sync your audio and video is with a simulcast device which is used in movie productions and such, but they are very expensive.

From the techincal side there are alot of ways to handle watermarking, all with upsides and downsides. It is in theory possible to replicate a file with the same watermark but differant video. But in theory I could win the lotto, get hit by a bus, get married to and divorce two supermodels and have a space station drop on my head in the same day. The odds of editing a file, getting something that "looks" right and matches the watermarking....is about as slim. And the guy who does it for you is a DaVinci caliber genius.

Or works for the CIA, FBI or NSA

Great imagination Thomas. Does your wife know about the two supermodels.

Good answer Thomas.

I may have to plaugerize that!

First, regarding police interview rooms or even any other combined (audio associated with video) audio/video interception the audio quality is the most important. The video just substantates and archives the event(s) and is often used to demonstrate the behavior of all parties (suspect(s) and agents/police officers).

It appears you selected a security type DVR which is designed mainly for timelapse recording etc. The audio sync problem will likely render the DVRs unusable for your intended purpose. Typically an agency requires what I call a "first" evidence recording. This has typically been fulfilled with VHS, 8mm or other tape formats, allowing the tape to be sealed as "evidence." However, all agencies are being forced to digital formats of some sort, to include optical and solid-state recorders with removable media. I would recommend using a CF card recorder which supports MPEG2 video and PCM stereo audio. I always use spaced-pair stereo mics with increases intelligibility. You can hear suspects breathing in my recordings. We have all watched those cheesey interview rooms recordings with muffled, low-level audio. Also, your client could use a cost-effective DVD recorder. You would most likely have to use an line time/date generator, which why timelapse VCRs/DVRs are often used.

Sorry for being long-winded. Good luck.

The audio quality is actually quite good to the point where you can hear a clock ticking on the wall that's barely audible when you're standing in the room.

The only real issue is the slight audio sync problem, and I'm hoping that it doesn't prove to be an issue. I guess that time will tell.

As a backup, we're providing audio cassette recordings, but as was explained to me, where there is both A/V and audio recordings, the A/V typically takes precedence because it provides evidence that the suspect wasn't forced to say something by intimidation (or torture I suppose).

Prior to starting this project, I searched for devices designed for this purpose and couldn't find any. Aside from the link to the Australian company that was posted above, are there any?

Pretty much the whole purpose behind this project was that they no longer wish to deal with the hassels of tape. Even with the VHS, security and tampering has never been an issue.

What are you using to record the audio? Mics, monitoring stations or such?

Louroe Verifact A's going through a Louroe preamp into an optional audio input card on the DVR.

2 rooms, 2 cameras, 2 mics.

The rooms however, are quite small. One is little more than 8x10ft, the other is slightly larger. Both have acoustic tile ceilings and sound soaking foam covering the walls.

You using an AP2? What Toshiba EVR, DVR or an older model?

You using an AP2? What Toshiba EVR, DVR or an older model?

Negative on the AP2. The mic preamp outputs are split. One set goes to the DVR and the other set goes to a pair of 19" LCD monitors.

The DVR is a DVR8-240-500

When putting this together did you contact Louroe to see what they recommended? Reason I ask is they usually would have suggested the AP for this type of senario. Also which is faster the audio or the video?

The video is actually a bit faster.

However, I've solved this problem by exporting to AVI format. That makes the sync much, much better.

Thats great!!!

Our legal system tends to work somewhat differently from yours, but one point that may be worth thinking about is multiple copies.

Where interviews are conducted for possible court use, it is becoming increasingly common to find three recordings being made at the same time ( one identical master each for the police, prosecutor and defence ).

Normal DVD recorders with a seperate TDG could be suitable, although I recently saw a DVR which had 3 DVD drives built in as standard.

The best way to sync your audio and video is with a simulcast device which is used in movie productions and such, but they are very expensive.

You can also try out a Hauppage PVR 150, about $65 and the quality blows the CCTV hardware out of the water. It only does 1 channel of video and 2 of audio though (DD passes through ).

They aren't a valid option fo a normal DVR as $65/channel with PCI socket limit.