Here's the story as told by the BBC website:
London Philharmonic to record Olympic nation anthems
Composer, conductor and cellist Philip Sheppard will take charge of the recordings, which will be played at the medal and welcoming ceremonies.
Recording starts in May at London's Abbey Road Studios.
It will take the musicians at least 50 recording hours over six days to finish the project.
Mr Sheppard said he hopes working at the iconic studios will help "creativity".
He has been working on the anthems since October, to make each one sound "unified".
Each anthem had to be up to a minute in duration and Mr Sheppard said it was a challenge to condense them.
"Uruguay is about six-and-a-half minutes long, so there comes a point where one has to chop it down, without offending the country in question," he told the BBC.
"But Uganda is only nine bars, so I had to come up with a way of making it last longer without it being repetitive."
London 2012 chairman and two-time Olympic champion Lord Coe said: "The playing of anthems at victory ceremonies is one of the most emotive parts of any Games and it was an incredible moment for me at the Moscow and Los Angeles Games.