By Darren Waters BBC News Online entertainment staff in Edinburgh

Mark Thompson filled the post left by Greg Dyke's resignation

Speaking at the Edinburgh International Television Festival, he said the BBC must continually strive for excellence.

The BBC has been criticised in the past for making programmes without a clear public service value or which are derivative of shows on other channels.

The BBC must add "something distinctive and original and valuable", he said.

That applied to genres such as light factual, leisure and lifestyle, format documentary, reality and some types of entertainment, he said.

Every couple of decades or so since its creation, the BBC has virtually re-invented itself Mark Thompson

But he stressed the BBC would not stop making these types of programmes, hailing BBC Two's Top Gear as an example of a leisure show with public value.

"There will always be room for the best and most original ideas in these genres.

"But it is also here that the temptation to give in to the derivative and the tired... is the greatest."

Mr Thompson said he would signal a shift in priorities to those genres that "build public value in a clear demonstrable way".

He highlighted news and current affairs as a key genre, as well as comedy, and said other priority genres would emerge out of conversations inside and outside the BBC.

"Although comedy is a branch of entertainment, I still think most people would accept that it too plays a critical part in reflecting our national culture and the way we live now."

Wide reviews

The director general gave few concrete examples of changes being made to the way the BBC is being run, saying many reviews were currently taking place within the corporation.

He said the BBC had teams "looking at pretty much everything".

"Every couple of decades or so since its creation, the BBC has virtually re-invented itself... we're approaching one of these moments again."

Stressing the need for excellence in all the BBC did, he said that was the one thing above all that audiences expected from the BBC.

"Because of the licence fee and because the BBC doesn't face the same commercial pressures as our competitors, they expect us to strive for it with more conviction and consistency than anyone else."