BBC director general Mark Thompson has told staff about plans to reduce the size of the corporation that will impact both on programming and jobs.
Plans are said to include a 10% cut in the number of programmes commissioned, which will lead to more repeats.
BBC staff have been told how many jobs are set to be cut, with up to 2,500 posts reportedly at risk.
The BBC needs to make up a £2bn budget shortfall, caused by a smaller licence fee settlement from the government.
The cuts - said to be centred on BBC News and factual TV, which makes programmes such as Planet Earth and Top Gear - will be imposed over the next six years.
No specific programmes have been targeted, however.
Make or break
On Wednesday, Mr Thompson's plans for the BBC's future were approved by its governing body.
ROAD TO THE BBC SHAKE-UP
January - Government raises licence fee by 3%, less than the hoped for settlement
March - Mark Thompson says BBC faces 'tough choices ahead' due to settlement
May - New trust chairman Sir Michael Lyons (pictured) says a debate about how the licence fee is used should be opened
August - Sir Michael says the BBC may 'do less' to meet a budget shortfall
October - Mark Thompson's strategy for the BBC's future is approved
BBC Trust chairman Sir Michael Lyons said the plans could be make or break for the corporation.
"All of this - the whole exercise - I see as focussed on ensuring that the BBC continues to be valued by the people who pay for it," he said.
The trust also backed "in principle" the sale of Television Centre, the corporation's studio and office complex in Shepherd's Bush, west London.
But it refused to confirm reports that it had approved proposals to place advertisements on the international pages of the BBC News website.
BBC correspondent Nick Higham said some 2,500 jobs would go, but that around 700 new jobs would be created, meaning 1,800 redundancies in all.
"The axe will fall most heavily on the London newsroom and on the departments making factual programmes and documentaries," he said.
Last week, some of Radio 4's most familiar voices, including newsreaders Charlotte Green and Peter Donaldson, joined the protest at the proposed cuts.
High-profile journalists like Jeremy Paxman and John Humphrys have also spoken out in recent months, prompting Sir Michael to urge staff to stay out of the public debate.
The BBC is expected to move towards an integrated newsroom
Broadcasting unions are opposed to the cuts, which could spark a series of strikes in the run-up to Christmas.
The government announced in January that the BBC's licence fee would rise to £151.50 by 2012.
Mr Thompson said the settlement left a "gap" of about £2bn over the six years.
The trust has already told Mr Thompson to make further efficiency savings of 3% each year.