A Victorian police officer has been sentenced to one year in jail for attempting to pervert the course of justice after he punched a teenager in the face.

The court heard Senior Constable Simon Mareangareu was the initial aggressor in the incident in the early hours of Christmas morning in 2014, when he punched 17-year-old Kyan Foster in the face, which was filmed by Mr Foster's friend on a mobile phone.

However the 54-year-old police officer's brief of evidence failed to mention the punch and said Mr Foster was the aggressor.

Mareangareu also attempted to persuade Mr Foster's mother not to contest the summary hearing.

County Court Judge Jeanette Morrish today described Mareangareu's conduct as "disgraceful and utterly abhorrent" as she handed down a 12-month prison sentence for his attempts to pervert the course of justice.

"Yours was not a spontaneous act, you set a course to cover your tracks and stuck to it," the judge said.

Mareangareu was fined $5,000 for punching Mr Foster in the face.

Kyan Foster said he was still "emotionally distraught". ( ABC News )

Outside court, Mr Foster said he was distraught from the process but happy with the judge's sentence.

"I'd just like to remind everyone that this case, it's not just about an assault, it's about false accusations against my person and an abuse of power in order to make those false claims seem legitimate," Mr Foster said.

"It's been a very long time coming, I'm very emotionally distraught from everything.

"I just need some time to wind down, but justice has been carried."

Video key in convictions: judge

Mareangareu told the court he stopped Mr Foster and his friend Stuart Laird, 16, as they walked home in Melbourne's east because they were wearing hoodies and backpacks and he was concerned they were going to rob a convenience store

The court released video footage of the incident filmed on Mr Laird's mobile phone to the media but noted it was not complete, did not capture the whole incident, the video had been enhanced, and the audio was not properly synchronised with the vision.

In the footage, Mareangareu demands the teenagers' names and addresses, telling them they are suspected of committing burglaries.

He then grabs Mr Foster's jumper, after accusing him of being a "smart arse".

Mareangareu told the court he punched Mr Foster "as hard as [he] could to the face", in line with his training, after the teenager "whacked" him in the arm.

The judge acknowledged Mareangareu's previously good record as a police officer. ( Supplied: Eddie Jim/The Age )

One of the officers can be heard saying "get rid of that video right now".

Mareangareu's colleague was not found guilty of any charges.

Mr Foster claimed the video had been deleted when he was released from police custody on the night of the assault.

The court heard Mr Laird's father paid experts a "significant sum of money" to have the video recovered.

In criticising Mareangareu's behaviour, Judge Morrish said there could have been "serious ramifications" for Mr Foster and Mr Laird if they hadn't been able to get the video back because it would have been the word of a senior police officer against two teenagers.

In handing down her sentence, Justice Morrish said she took into consideration Mareangareu's record as a police officer.

She described him as a "man of undoubted good character" who on three separate occasions had risked his life to save others.

Justice Morrish told the court an off-duty Mareangareu once swam 200 metres in treacherous waters to save a man who was struggling in the water.