Sales of portable media players are expected to double in 2005 after the industry sold 25.6 million units in the first half of the year, almost equal to the total for the whole of 2004.

Analyst firm Canalys said in its Digital Home Analysis report on the state of the industry that Apple is leading with 44.8 per cent of the market, compared to Creative's 16 per cent share.

But Apple's lead is even more commanding in the high value hard drive segment, thanks to the success of the iPod. 

More mobile phone/media player hybrids, such as the Motorola Rockr launched this week, are coming onto the market, but are not expected to make much of an impact, except at the low end, even with downloading straight to the handset. 

"A mobile phone-based player does not offer much to a high-volume music consumer," said Canalys analyst Rachel Lashford.

"The convenience of having to carry one less device will usually be outweighed by the design compromises that result.

"And a heavy user is not going to pay a premium to download each track over the air to a phone when there are cheaper service alternatives that offer a more sophisticated browsing experience, interface and file management."

Lashford added that some mobile phone companies may limit the capacity of music players built into mobile phones since it generates little in revenue and could distract from calling.

However, some manufacturers may try to make it difficult to transfer files from a PC to a phone in an attempt to boost download and ring-tone revenues.

The report warns against this approach, pointing out that consumers will switch device rather than pay more.

This is worrying news for Motorola, since the Rokr is limited to 100 songs, no matter what size of storage card is inserted.