Rhys Ifans and Dr Who writer Russell T. Davies are among those taking part in the Celtic Film and Television Festival which begins on Wednesday.
Rhys Ifans is coming to the Celtic festival for the first time
With more than 400 delegates, the 26th annual event, hosted in Cardiff, is one of the biggest staged.
Delegates from France, Cornwall, Ireland and Scotland are coming to the Welsh capital for the four-day event.
Cardiff marks its centenary as a city in 2005 and the local authority is the main backer of the £250,000 festival.
Launched in a hall in Benbecula in the Scottish Hebrides in 1979, the event last came to Cardiff 21 years ago, although it has since visited other venues around Wales.
Frances Hendron, the festival's chief executive, said it was an exciting time to be back in Cardiff.
"We've had a huge growth in the industry since then," she said.
The last 26 years have seen the establishment of S4C and other minority language television channels and a huge growth in the independent media sectors across the participating countries.
One discussion session at the festival, chaired by Welsh Language Board chief executive Meri Huws, centres on the future of minority language television, and whether its role should be to promote the language.
"It's a challenging time for minority language participation in the industry," Ms Hendron said.
"It's great to be back here in Cardiff. We're celebrating the best of production in film, TV and the media industry. And we're also celebrating 100 years of Cardiff as a city and 50 years as a capital".
The Scottish film Dear Frankie is competing for a prize
Notting Hill star Rhys Ifans is coming to the festival for the first time on Wednesday, keen to show his support for the Welsh language in which he first launched his career.
Writer Russell T Davies is also taking part in a writer's workshop, fresh from the successes of the latest Dr Who series, produced by BBC Wales.
Organisers are hoping the Welsh public as well as members of the film and media industry will join in.
Sixty people are taking part in a youth forum which launches the four-day event and aims to show youngsters a way into the industry.
There is also a drop-in workshop at Chapter Arts Centre in Canton, Cardiff, on Thursday.
To celebrate the return to Cardiff, the arts centre is also showing three award-winning films from previous festivals alongside Scottish entry Dear Frankie and others competing for this year's title.
The highlight of the festival is the Spirit of the Festival Award, which is presented on the final night.
The festival's producer Hannah Raybould said: "Everybody collects their prize with a speech in their own language. It's really great to hear people speaking in their own languages - Gaelic, Breton, Cornish and Welsh."