Police Cameras Are Valuable… But Not If They Can Alter The Videos

from the trust-goes-out-the-window dept

We’ve talked plenty about the value of body cameras and dashcams for police — in acting as a deterrent to bad behavior by police while supposedly acting as public servants. Of course, that only works if people trust the video not to be edited and doctored. This week there are all sorts of questions being raised about the arrest and hanging death of activist Sandra Bland in Texas. There are plenty of questions about why she was even arrested in the first place, and then plenty more about why she died (the police called it a suicide, which many who knew Bland find highly questionable).

In response to some of these concerns, the police released a 52 minute version of the dashcam video of her arrest — though for some reason, the YouTube version has since been taken down. Perhaps it’s because people watching the whole thing noticed a bunch of really sketchy problems with it that suggested the video had been edited, while the audio remained in tact. Ben Norton first posted the details of these, highlighting a bunch of weird artifacts like disappearing cars that magically reappear seconds later:

Or the tow truck driver who gets out of his truck, walks behind the car and out of frame… and then suddenly gets out of the truck again:
You can skip your “glitch in the Matrix” jokes. They’ve already been made. Plus, this is about someone who died.

The Texas Dept. of Public Safety said it would look into the video problems, and officials have denied any edits and have said that they will re-upload the video (which likely explains why the original has now gone missing). It also seems worth noting that the timing of the edits doesn’t make it look like anything important was edited out (it all happens after the arrest itself).

It’s possible that there was just some sort of weird glitch with this footage, but it’s a reminder that anything that calls into question the credibility and accuracy of these kinds of videos will only undermine the purpose of these videos. We’ve heard too many stories about how some of these cameras can be “turned off” or that police would have access to the coverage before it’s released to the public. If officials want these systems to actually work, they have to be trustworthy on their own. While this is likely just going to turn out to be some sort of technical problem that will be fixed, with nothing nefarious at all, it still acts as a strong reminder for the need to make sure that this kind of footage is stored and released in a way that doesn’t raise such questions.

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Comments on “Police Cameras Are Valuable… But Not If They Can Alter The Videos”

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Ehud Gavron (profile) says:

Real video has time stamps

Real law enforcement video (that can be used in court) has either a frame-counter (so every frame has an incrementing number) or a timestamp with fractional seconds so every frame has a different timestamp.

This video doesn’t. The video is clearly a composite (many different segments put together to make a longer product) sync’d with a soundtrack from a different video.

There is *no way* this is anything other than intentional. The sheer number of decisions required to come up with this, let alone post it, is second only to a lane-changer embarrassed to death. Suicidal death.

soulsabr says:

Re: Real video has time stamps

Not to mention that digital video “errors” like they claim are not clear nor do they skip backwards. A real digital video error would look like … how to put this. It would be like a single frame of video that suddenly looks like the outline of the people walking around and talking. That is what it would look like for a few seconds due to how digital video works. Any skip back HAS to be intentional simply because digital video does not work that way.

Eponymous Coward (profile) says:

You know...

The ACLU (and others) already has several apps for secure upload and storage of video of police encounters. PDs could save a lot of money if they just made use of these free apps.

A third pary video escrow service, while anathema to government agencies’ “we control the information that should be free and public” attitudes, could provide some much needed goodwill.

Anonymous Coward says:

Local news had a segment on this where they stated (and that perhaps Texas officials told them – I didn’t quite catch that part) that the camera has an auto-start-stop function based on motion and maybe also sound.

Maybe explains most or all of it? Would not explain the tow-truck operator exiting more than once, unless he went back into the cab before exiting (“oops forgot something”).

Roger Strong (profile) says:

Re: Re:

A good auto-start function would start several second before whatever triggered it.

For example my own in-car camera is always recording while the car is running. It’s recording in a loop, continuously recording over what came half an hour or so before.

If I want to KEEP the video, I hit a button on the camera. Of course by then the accident or other incident has already happened, so the recorder preserves the video starting from several minutes BEFORE I hit the button.

I suspect that this patrol car’s camera is always continuously recording. What the auto-start function does is preserve the recording starting from a moment before motion triggers it. The flashing tow truck lights trigger it several times in a few seconds, and each time it preserves the video from MORE than that few seconds before. So you see the same cars go by several times.

But that’s just a guess.

Anonymous Coward says:

Re: Re: Re:

So what you’re saying is that whoever made the camera didn’t know how to properly implement a start and stop function? While I’m no expert by a long shot I’ve never seen that before and I would imagine that camera manufacturers would know better than mess up so badly.

Roger Strong (profile) says:

Re: Re: Re: Re:

I’m not saying that it messed up at all.

Sure, the motion activation system is probably not handling the flashing tow-truck lights as well it would the occasional car or person going past.

But as long as it’s not losing video, that might be considered good enough for law enforcement purposes. “Don’t excite the conspiracy theorists” was unlikely to have been in their design criteria.

Again, I’m guessing here. But it’s a guess based on some experience with similar cameras.

Anonymous Coward says:

Re: Re: Re:

What those cameras do is record short segments, often 1 minute at a time, and those segments can be played consecutively without any artefacts. When you hit the record button, the last several minutes worth of segment are marked as keep. So repeatedly triggering record does not cause multiple recordings of a minute worth of video, just a redundant keep re-marking of some segments.

Anonymous Coward says:

Re: Re:

Auto start/stop does not result in repeatedly looping footage while leaving associated audio intact. It is painfully obvious that the video portion of the feed is being looped to obscure something else that happened onscreen. Odds are, whatever is being covered-up will manifest itself on another video outside of their control.

Pronounce (profile) says:

Malcolm Gladwell's "Blink"

My first thought when I read the original news release was, “dead men tell no tales.” Gladwell’s book discusses how our subconscious works out the details before our conscious does.

I suspect we will never no the truth, but if we did it serve as another reminder that the government deals harshly with thorns in its side. (I’ll not reference the mountain of cases where this has been proven to be the case. The reader will choose to believe what they believe.)

Anonymous Coward says:

Cop lied in tow truck segment

He did NOT explain to her what he was doing and what was going on, as he said he did, when he stepped back from the car.
On the contrary, he REFUSED to tell her anything in response to repeated questions from her. He did tell her that if she didn’t get out of the car, he would “light her up” as he was brandishing his TASER.

Smoking in own vehicle while black is now a crime, I guess.

I agree wholeheartedly with Sandra Bland when she called this pig a pussy.

OldMugwump (profile) says:

Should be able to tell

I know something about digital video encoding – given access to the original bitstream posted by the PD, it should be pretty easy to tell if it was edited or not.

And I’m sure somebody is doing that analysis right now.

Video aside, cops have been beating up people who don’t show proper respect (esp. if someone “unimportant”) for as long as there have been cops. I don’t think it’s anything new.

What is new is video cameras in everyone’s pocket. Cops seem to be having a huge amount of trouble adapting to the new situation.


Anonymous Coward says:

DPS response

“The video has drawn criticism for gaps and overlaps, but the Texas Department of Public Safety insisted today that it had not been doctored.
DPS spokesman Tom Vinger said glitches in the recording occurred when it was uploaded for public viewing.”

Any one know which encoding codec you can use to upload to youtube that will screw with the video but not the audio?

I’m calling a very high probability of bullshit on the DPS.


Anonymous Coward says:

Re: Time Stamps on Police videos

Actually I youtube searched

‘Texas LEO dashcam footage’ (no quotes)

and, at least the first two videos that came up


That is




Don’t have a timestamp. Perhaps the timestamp you see is on the Youtube preview pic, which seems to be a youtube timestamp.

The third video that comes up


does have a timestamp and the timestamp doesn’t have its own background.

Anonymous Coward says:

The video confirms there was no reason to pull her over

From what I’ve read at other sources, the video also confirms that the police had no reason to pull her over.

The officer was driving in the opposite direction of Bland, then suddenly made a 180 turn and sped up towards Bland. Bland switched lanes to try to get out of the officers way.

The only thing even semi-illegal Bland did was forgetting to use a turn signal when switching lanes to get out of the officer’s way.

JoeCool (profile) says:

Re: The video confirms there was no reason to pull her over

Used to live in TX years back, and at the time it wasn’t law to signal for a lane change. In fact, people WOULDN’T signal a lane change because if you did, folks in that lane would block you out to prevent you from getting in the lane and slowing them down. In fact, if you saw signals for lane changes, they were FAKE – signaling the wrong way to trick you so you couldn’t block them out.

jilocasin (profile) says:

What could be in those missing segments...?

I wonder what could be in those missing segments…..

The officer making questionable comments on:

her race and lineage
her history as an activist
references to the KKK or other like minded groups
allusions to lynching

Naw….. it’s probably inconsequential material with no bearing on the incident at hand. They were just streamlining the file so that it would upload quicker. Yep, that must be it. /s

Another Anonymous says:

... if they can alter video,

Then everyone involved should be separately recording the same events, and be encouraged to do so.

This ensures that any attempt to falsify evidence on video would be invariably exposed by the redundant copies. Therefore, it would be foolish to even attempt a falsification.

If a policeman attempts to stop a participant or bystander from recording the official interactions, that action alone should be accepted as evidence that the policeman’s claimed position is invalid.

NeghVar (profile) says:

As a digital forensics student

As a digital forensics student, time stamps are not a way to verify integrity. They can be altered with any easily accessible, free metadata editor. The best way to confirm authenticity is to use stenography. The company I work for does remote security surveillance. When video is needed, it is extracted from the DVR or NVR. During the extraction process, a signature is embedded in the video file. If the video is presented in court and the authenticity is challenged, we provide our software and key to present the signature. If it is there, the video is authentic and genuine. If the signature does not appear, then the video file has been compromised and can be thrown out.

Anonymous Coward says:

Re: As a digital forensics student

When video is needed, it is extracted from the DVR or NVR. During the extraction process, a signature is embedded in the video file. If the video is presented in court and the authenticity is challenged, we provide our software and key to present the signature.

I’ve reverse-engineered similar software, and it’s often laughably bad. One system used an HMAC, which means that the verification software needs the same key as the software creating the signature. (These keypairs weren’t per-recorder either. All software had the key embedded.)

The system you described has an obvious weakness: the signature is created on extraction, not recording.

We need systems that can be verified by others, not proprietary black-boxes. As a student, can you explain the system in detail? Could you write an academic paper describing the algorithms, with independent software to verify the video? Can you explain the threat model and countermeasures employed? What extent does someone have to go to to fool the system? E.g., does the attacker need to have physical access to the police car that recorded the video, or can they fake a signature from their dorm room with only an MP4 file?

Anonymous Coward says:

This whole situation is fishy as hell. The alleged victim resisting arrest, her self-harm scars and prior claims of depression and PTSD, that she was an “activist” (which means anything in the range of “signed an online petition” to “burned and looted in the Baltimore riots”), and, of course, the races of the involved parties.

I suspect that the police department tampered with the footage without being fully appreciative of the fact that their amateur attempt at spin doctoring can’t hope to compete with the masters at “news” outlets like TYT, MotherJones, and The Guardian.

Step two for this media-manufactuted hysteria will involve increasingly ludicrous speculation (à la “hands up, don’t shoot!”) to rile people up as much as possible before the facts start coming out and burst this bubble. Just like with Rodney King. And Michael Brown. And Freddie Gray. And and and.

Every time they cry “Wolf! Wolf!”, they lose credibility and grant the government leeway for actual abuses of power.

Stephen says:

It's Not just Video Editing

In a number of US police dashcam videos I’ve watched the police leave their vehicles with their car DVD/radios blaring music at full volume.


Well, one reason that comes to mind is that it would reduce the chances of the dashcam’s microphone picking up what is said during any altercation outside the police car.

WTH says:

You don't have to encrypt, just create a hash of each frame...

…and upload the hashes somewhere out of their reach. Then they can do whatever they want with the video, as long as they don’t claim to destroy the original you can trivially detect changes.

It is also very easy to detect changes by noting the increase in certain frames types in the video (presuming they’re using modern compression.)

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