Giants and upstarts of publishing gathered at the annual BookExpo America here this week agreed e-books will transform the business, although exactly how it will all shake out remains unclear.

From biggest publishers to newcomers there was agreement on one thing -- the big change will come when there is a standard format across which all e-books can be published and shared.

The industry has been going through a tumultuous period as Apple and Amazon duke it out for dominance in the nascent market for electronic books.

Both want their devices -- the iPad and the Kindle -- to be the one consumers use to read e-books, and each wants to be the biggest virtual store were such content is sold.

For Michael Serbinis, chief executive of Kobo, a company that allows users to buy e-books and read them on most devices, that battle is a distraction to the real changes coming.

Today you can buy a book at Barnes and Noble and you can buy a book at Walmart and you don't have to keep them in separate rooms in your house, he said. You buy a book from Apple and Amazon and you have got to keep it tied up with your Apple universe or your Kindle universe.

Ultimately, consumers want freedom, said David Shanks, chief executive of leading publisher Penguin Group USA.

Our fondest wish is that all the devices become agnostic so that there isn't proprietary formats and you can read wherever you want to read, Shanks told Reuters. First we have to get a standard that everybody embraces.

The issue, he said, is the fear of piracy and how to set a common digital rights management system to thwart it.

The battle over technology formats is a familiar one. A century ago, Edison and Victor made records that could not be played on each other's players. There was the Betamax/VHS videotape struggle and more recently Blu-ray beat out HD DVD.

BookExpo showed traditional books are alive and well. There was buzz for the upcoming book from news parody king Jon Stewart and raucous Rolling Stones guitarist Keith Richard's memoirs as well as a book on home design by Barbra Streisand.

EVIDENCE OF INNOVATION

And there was evidence of change coming in the age of e-books, although the new format was displayed only in one small corner of the sprawling Javits Center convention halls.

Among the digital companies here were Sideways, which helps authors and publishers transform text into multimedia content, adding video, pictures and features such as Twitter feeds.

Another company, Ripple, allows adults to buy children's e-books and record their voices reading them. And there were gadgets such as the enTourage eDGe -- a twin-screened device which opens like a book to reveal an eReader on one side and a NetBook on the other.

Eileen Gittins of Blurb, which helps authors and companies self-publish, predicts e-books will make up half of all sales in five years. In 2009, the global publishing business, including print and digital, was worth $71 billion, according to PriceWaterhouseCoopers.

We're seeing now in book publishing what had happened previously in the music publishing industry. And that is, a massive disruption of the business model, she told Reuters.

The problem is that the cost of printing is a minor cost of publishing whereas developing work with an author and marketing it consume the lion's share of costs.

That means, she said, that the book industry will become more like the movie business. The book publishing industry is becoming more blockbuster focused, she said.

Susan Petersen Kennedy, president of Penguin Group USA, said publishers will not make the same mistakes as the music industry, which had an epic struggle over electronic distribution and piracy and lost huge market share.

It's always treated as if the publishers are the Luddites, she told Reuters in an interview. The devices have not caught up with the content. Contrary to popular opinion, the book is actually so far more flexible.

Serbinis says the industry will see dramatic change. He predicted consolidation among publishers and said tablet computers will be common. He expects readers to eventually be able to lend e-books to each other.

And books won't just be for bookstores any more as new distribution channels from mobile phone companies to gaming companies join the party, he said. It won't only be the bookstores that have gone digital, he said.