AHEM

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.

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.

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

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.

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.

I can't exactly answer your question, but I really like the Verifact A mics. When you're looking to pick up a whisper from 30 feet away, they're for sure the way to go, but due to their sensitivity, they're also fairly easily overloaded. Perhaps a compressor/limiter would help the situation?

Good answer Thomas. I may have to plaugerize that!

Thank you for the warm welcome! Excellent link. Thank you. I wasn't aware of that organization. BTW, I'm from Indiana. I'm recording 30 FPS at the highest quality setting. 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? 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.

Thanks. That does look to be helpful. I'll study it and pass it on to the powers that be. Yikes! Thanks for the warning. Are there any that you would suggest? 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.