noise distortion on some channels

[simonb]

this is really odd - i have noise distortion on lots of channels eg BBC sky etc - but none on ITV channels - even when i playback recording from the box BBC is distorted and ITV recordings are fine - done the switch off and on -thanks  edit  - it appears the sound is out of sync with the picture but still distorted 

[simonb · Accepted solution]

update - found the answer to set the audio to Dolby which fixed the problem