A mum put on a DVD and found herself watching video footage of her own baby boy being abused in his cot.
In what must be every parent's worst nightmare the woman watched in increasing horror as her 15-month-old boy was slapped, poked in the face and bombarded repeatedly by a a ball thrown at his head, Guildford Crown Court heard.
The sick film of the baby sobbing in terror was made by the 24-year-old man who carried out the sadistic assaults.
Mark Weatherall, 24, a builder's labourer from Surrey, was jailed for 12 months after pleading guilty to child cruelty.
The horrifying home movie was shown to a hushed courtroom before the defendant was sentenced.
A member of the public sitting in the Court's gallery fled the room in tears after witnessing the graphic scenes of the tiny victim's suffering.
Sending Weatherall, to prison, Judge Christopher Critchlow told him: "Anybody watching that would be appalled by what you did."
The judge went on: "It was a form of torture. It is difficult to understand why anyone could do such a thing to a defenceless 15-month-old baby in his cot."
The court was told that Weatherall was acquainted with the baby's family and carried out the sick acts whilst he was alone with the child last December (2012).
Wendy Cottee, prosecuting, said that the child's mother had, out of curiosity, put on a DVD which she did not recognize
"What she saw horrified her," said Ms Cottee.
The film seen by the Court depicted the child crying and screaming in fear as he was repeatedly slapped and poked in the face and had a ball thrown at his head again and again.
Ms Cottee said that Weatherall would also pick up the baby by one of his legs and drop it.
"It's a very disturbing case. she said, "It appears to be gratuitous violence."
The court was told that Weatherall would record his actions either on a mobile or a web cam before downloading the material on to a disc - which led to him being discovered.
Judge Critchlow told the defendant: "People would also be appalled that you should film these acts of violence."
The Court heard that the tiny victim had escaped any noticeable signs of injury as a result of his ordeal.
But Ms Cottee said: "The child has been affected by what has happened and now had a tendency to slap adults in the face."
It was revealed that Weatherall had been using cannabis at the time of the offences.
David Smith, defending, said: "My client has had a fairly appalling upbringing".
He said Weatherall had also experienced violence from an adult when he was a child.
But Mr. Smith stressed: "I don't want to minimise the gravity of the offence".
He added that family members of the baby had shown the defendant nothing but kindness in the past.
Weatherall is now banned from working with children in the future.