That's a good idea: Story to screen II.I

When the great studios ruled the earth, their appetite for stories was immense. Hack writers were practically chained to desks, grinding out ideas and treatments. A typical studio needed to churn out 100 movies a year. Stars demanded vehicles; quotas of genre pictures were required; all the time a weather eye had to be kept on the prevailing climate of the market.

Hollywood may no longer be the sausage factory it once was, but the industry is still greedy for fodder. There may be more reliance on a few blockbusters to bring in the profits, but there is a huge market for straight-to-DVD movies, drive-in exploitation-flicks and the TV movie has replaced the B-movie and at times rivals the theatrical product. And I'm not even going to think about Bollywood, which churns out 900 films a year.

I suppose the bulk of movies are based on the efforts of story-writers or come from novels, short stories and plays. But it's interesting to look at some of the other sources.

First, a word on books and plays. Many of them are aimed at the cinema when they are written. Much popular fiction is influenced by film, thrillers especially. Look at the Constant Gardener:

• Plot - thriller with a conscience, very much the vogue.
• Exotic locations
• Hero and heroine crying out for star actors
• Good cast of well-defined character parts
• Add to these that Le Carre knows that any novel of his is almost certain to be taken up by TV or cinema.

The same could be said of Elmore Leonard today and Chandler and Cain in former times. I hear that Forrest Carter sent the galley proofs of his Gone to Texas to Clint Eastwood, who bought it immediately and turned it into The Outlaw Josey Wales.

There was a time when comic books were thought fit only for transposition to TV, but it was probably Superman that demonstrated their cinematic potential. Since then we've had Batman, Spiderman and others that I can't bring to mind, nor do I wish to.

TV itself seems to have been taken up with enthusiasm of late, especially since The Fugitive with Harrison Ford. The Dukes of Hazzard, Miami Vice are a couple of examples. I suppose the idea is to cash in on the nostalgia of the older generation and try to capture the younger with modern thrills and spills.

Historical events - or a version of them - has always provided useful source material for the movies, one of the earliest being Birth of a Nation. More recently we have had The Alamo. I single this film out, partly because of the excellent portrayal of Davy Crockett by Billy Bob Thornton, but mainly because of its attempt to be more faithful to historical fact. This is a recent trend. The 1946 John Ford film, My Darling Clementine, purports to be an account of the gunfight at the OK corral, and while, in my opinion, by far the best movie on the subject in cinematic terms, is a complete joke as far as historical facts go. Ford claimed to have got the 'facts' from Wyatt Earp himself, which hardly boosts confidence anyway. Compare it with Tombstone and Wyatt Earp, still dubious, but at least they got the brothers in the right order of age and death.

The biography is an offshoot of the above and has always been popular. Like the historical film it appeals to those who wish to 'learn' as well as be entertained. These are the same people who claim to watch television for the news and documentaries. Biopics seem to come in waves. In fact movies always seem to come in waves of some sort as producers follow apparent trends in the market. Warner Brothers did Ehrlich, Pasteur, Zola and Juarez (the last three vehicles for the histrionic talents of Paul Muni). And very recently we've had Ed Murrow and Truman Capote.

A lot of people justify a trip to the pictures by telling themselves the film is 'educational'. Let them try Cromwell, Richard Harris' impersonation of the great man. I suppose it got the gist of the story, but when you see the Lords and Commons sitting in the same chamber you do wonder where they got their information from.

If history's not your thing, there's always myth - Robin Hood, King Arthur, the Greek myths, which Ray Harryhausen had such fun with. Most recent, I suppose, Troy. I don't care what the critics said, I thought it was pretty good. Brad Pitt can't help being pretty, he's bloody good. Now Tom Cruise has imploded, I predict Brad will be the next Clint. Mark my words.

So what other sources have we got. Johnny English was based on an advert (does the same apply to Transfformers?); Road to Perdition came from a graphic novel, which seems to be the way to get your story on screen these days - see also Sin City and History of Violence; The Charge of the Light Brigade was inspired by a poem, Convoy by a song; and famously It's a Wonderful Life derives from a Christmas card. Die Hard 4.0 derives from a newspapaer article.

Oh, and let's not forget the franchises, not a word I recall being used 20 years ago, it was just sequels then - Bond, Die Hard, Jaws, etc. The remakes - The Lady Killers, Alfie . . .The trends - the spate of gangster films after The Godfather; serial killer films after Silence of the Lambs; ghost stories after Truly, Madly, Deeply. It's nothing new. There were many films about ghosts, angels, etc during world War II.

Roger Corman made a fortune and many, many careers in the exploitation business.

In Sunset Boulevard Bill Holden's writer complains about the way one of his stories was treated. 'The last one I did was about Okies in the dust bowl. You'd never know because when it reached the screen it took place on a PT boat.' I plan to talk about the evolution of an idea from story to finished movie another time, but some of the greatest are based on original stories, including Sunset Boulevard itself.