The police department in Birmingham, Ala. has seen a 71% drop in citizen complaints -- and a 38% drop in use of force by officers -- since deploying 319 body cameras two months ago.

The cameras have been so effective that the department plans to buy another 300 cameras from Taser International.

"The chief's goal is to get a camera on everybody who wears a uniform," said Capt. William Brewer, who heads up Birmingham Police Department's Technology Division.

Birmingham is among a growing number of police departments that are rolling out body cameras, spurred in large part by public pressure in the wake of a series of controversial police shootings of civilians. That pressure first began to mount nationally last year in the wake of the shooting death of Michael Brown, in Ferguson, Mo. Several other high-profile police shootings since Ferguson have added fuel to the body camera fire.

Even so, there's been little focus on the larger ecosystem needed to make the cameras useful, including potentially high storage costs -- petabytes of video are now being uploaded annually -- and file management concerns.

In Birmingham, for instance, the the video cameras themselves cost about $180,000, but the department's total outlay for a five-year contract with Taser will be $889,000. That's because the pact not only includes a hardware replacement warranty, but the necessary cloud storage and file management service to deal with terabytes of content the cameras are producing.

The Birmingham police initially purchased 5TB of online storage on Evidence.com, Taser's file management cloud, which is built on Amazon's Web Service (AWS) platform. In just two months, however, the department has already used 1.5TB of its allotment -- and it's on track to exceed the 5TB limit in about six months.

"That's the biggest problem with this system...the cost of the storage," Brewer said. "They do offer unlimited storage, but it's quite costly -- well above $1 million for the package we had looked at."

Traditionally, police departments saved dash camera footage and other videos on CDs stored away in an evidence room or on an onsite server. But with the increasing use of body cameras, dashboard cams and cameras within the police department itself, the amount of video content now being generated is far more difficult to manage locally.

The cameras are just the start

Body cameras are the fastest growing segment of the police video camera business. The two largest police body camera manufacturers today -- Taser and VieVu -- say they've shipped devices to 41% of the nation's 18,000 police departments.

VieVu VieVu's LE3 body camera mounts to an officer's vest or shirt.

But it's not the cameras that generate the most money. Glenn Mattson, who follows Taser as an equity analyst for Ladenburg Thalmann, said the company makes a far bigger profit on its storage service than hardware. Last year, Taser's gross profit margins on hardware were 15.6%; the gross margins for video storage were 51%, Mattson said.

"There's no contest. They don't care about making money on the cameras," Mattson said. "If they can just break even on them, it's fine, because they're going to create this high margin stream of revenue on the video side."

Mattson believes that, on average, police departments pay Taser from $25 to $30 per officer per month right now. But he expects that to rise, and compared the police video storage business to cable subscription services. While the initial cable subscription is usually a great deal, once new services are added, rates climb.

Mattson believes Taser's plan is to add features so it can become a police department's default system for every kind of digital evidence, including photos, police reports and forensics data.

The cost of data storage has forced the Birmingham Police Department to make hard decisions when it comes to deleting videos to free up space. Since Alabama records retention laws haven't caught up with video technology, police departments are left to determine their own policies.

Taser International Taser's two camera models, the Axon Body, a self-contained unit worn on a vest or shirt, and the Axon Flex, which can be affixed to an officers cap or glasses.

Birmingham has come to a consensus with its district attorney on a general retention period of two years, but it's still "battling" with its own legal department.

"We're still trying to make sure we don't delete them in violation of Alabama records retention laws," Brewer said. "Unfortunately, our state, along with probably many other states, has not caught up yet in dealing with this type of technology."

How long police departments store video varies widely depending on local policies. But in some cases, such as a murder investigation, the video will need to be stored forever.

Brewer said his department will likely have to extend the video retention period from two to two-and-a-half years, not because of criminal investigations, but because of lawsuits and civil litigation.

"In our state, [citizens] have up to two years to file a lawsuit. So we need to realistically keep everything two-and-a-half years to give us time to be notified of an impending suit," he said. "They're always wanting that video after it's rolled off the server."

A sales chart 'like a hockey stick'

Taser, which got its start in the law-enforcement video business by affixing cameras to the company's handheld electroshock weapons, has seen brisk body camera sales. The company ships about 7,000 camera a quarter, according to Mattson. In all, about 35,000 have been shipped to date, he said.

As of the first quarter of this year, more than a petabyte (one million gigabytes) of police video has been uploaded to Taser's Evidence.com service, according to Taser spokesman Steve Tuttle.

"A video is uploaded every 2.9 seconds," Tuttle said.

In the second quarter of this year, Taser's Axon camera and Evidence.com cloud storage service saw $30.6 million in sales, up 170% compared to a year ago, according to the company's earnings call.

"You can see it's growing like a hockey stick," Mattson said about Taser, which now has 26 major cities on its Evidence.com platform.

Seattle-based VieVu, which was acquired earlier this year by police and military supplier Safariland Group, was the first to introduce a police body camera. The privately-held company recently introduced its hosted evidence management service called VERIPATROL, which is based on Microsoft's Azure Government cloud platform.

The VERIPATROL evidence management service comes in three iterations: an onsite software model, a fully hosted cloud model or a hybrid of the two.

VieVu CEO Steve Ward said he doesn't know how exactly many videos have been stored to date on the VERIPATROL service. But "it's in the millions."

For example, VieVu's largest client, the Oakland, Calif. police department, has already stored one million police videos in the five years its officers have been using VieVu's body cameras.

"Over the last eight to 10 months, we've seen a dramatic shift in police agencies realizing, 'We're not IT shops. We need to make a shift to the cloud,'" Ward said.