Video clips of a baby boy being slapped and kicked by his mother's boyfriend were shown to a court yesterday.
Baby Charlie Hunt, 15 months, died from serious head injuries.
Before they were shown the videos, jurors were warned about the "distressing and shocking" footage. It was taken on a mobile phone by 32-year-old Darren Newton.
Newton filmed the attacks for his own 'wicked pleasure' while Charlie's mother, Laura Chapman, was out, the jury was told.
Newton, of Earby, Lancashire, pleaded guilty to 12 counts of child cruelty but denies murder.
He also denies two offences of child cruelty.
Manchester Crown Court was told police found the clips on Newton's mobile, including one called "happy slap". Other titles shown included "crying", "no toys in pen ah", "2 minutes of pain" and "squeezing toe in cot".
In one video Charlie sat shivering naked in an empty bath. Later that day, Newton filmed himself hitting Charlie on the head repeatedly and then kicking him, the court heard.
Denis Watson QC, prosecuting, told the jury Newton 'took pleasure from the fact that Charlie was the victim of his cruel and wicked behaviour'.
The video clips 'demonstrate a pattern of behaviour repeated by the defendant on occasions when he was in sole charge of Charlie,' he said.
He added: 'The defendant not only filmed his actions but he titled them as well... they were retained for repeated viewings.'
Mr Watson said Newton repeatedly assaulted Charlie between June and November 19 last year.
He said: 'Charlie was it seems happy and well when he was with his mother and babysitter that morning. However, at 2.30 that afternoon, the defendant was left in sole charge of Charlie and by 5.45 Charlie was dead.'
Medical experts said Charlie died of head injuries consistent with 'a deliberate application of force'.
The trial continues.