Northern Territory police have begun a three-month trial of body-worn cameras recording high-definition video and audio.

The officers have unrestricted powers to record wherever they go in the course of their duties, including public spaces as well as private places such as homes and offices.

Police say the front-mounted digital cameras will help improve police transparency, reduce paperwork, and supply useful evidence to the courts.

The Reveal RS2-X2 video camera being trialled by Northern Territory police. ( ABC News: James Purtill )

Use of the cameras in policing is an emerging trend both in Australia and overseas.

In the United States, there have been calls for police officers to wear body cameras following the fatal shooting of a black teenager in Ferguson, Missouri.

President Barack Obama recently proposed equipping 50,000 officers with the cameras.

In November, New South Wales parliament passed a bill giving frontline police the power to use body-worn video cameras following widespread trials earlier in the year.

It has been proposed the cameras will eventually be worn by every NSW frontline officer.

In recent years there have been limited trials in South Australia, Victoria, Western Australia and Queensland, including at the recent G20 summit of world leaders in Brisbane.

Here is what you need to know about the Northern Territory police's body-worn camera trial.

What kind of camera?

The Reveal RS2-X2. Unlike other body-worn cameras trialled in Australia it has a screen that faces outwards and shows what the camera is recording. "The person they're recording can see their image on the screen facing them at the time," Acting Deputy Commissioner Reece Kershaw said at a press conference announcing the trial.

It records high-quality video and audio, has a 120 degree horizontal field of view and weighs about 130 grams.

Will every officer have a camera?

No. Forty cameras have been allocated between officers across the NT. Twelve cameras will be sent to Alice Springs, six to City Safe, six to Darwin Traffic Operations, four to Drug and Organised Crime Squad, and 12 to the Metropolitan Patrol Group.

Does the camera record all the time?

No. "Officers will press record when they execute their police powers or make customer contact or custody or when there is a likelihood of custody incident," Acting Deputy Commissioner Kershaw said.

Can I ask police to stop recording?

Police do not require your consent to record. "They can ask that question however the officer no doubt will continue to record," Acting Deputy Commissioner Kershaw said.

Where can police record?

Police officers may use them anywhere in the Northern Territory. The only restrictions are those that generally determine where police may go.

What happens to the video?

The data is stored on a "secure server". If the video is being used as evidence then it will be made available to you, your legal representative as well as the prosecution.

If the footage is not being used as evidence it can be obtained for a $115 fee. You may not access footage of others.

Data not being used in court will be destroyed after 110 days.

When does the trial end?

The trial ends March 31, 2015.