Blu-ray successor plan unveiled by Sony and Panasonic

Sony and Panasonic have announced plans for a successor to Blu-ray discs.

The firms say they want to develop an optical disc capable of holding at least 300 gigabytes of data by the end of 2015.

By contrast, normal dual-layer Blu-rays can only hold up to 50GB.

Sony has previously said that 4K ultra-high-definition movies - which offer four times the resolution of 1080p video - were likely to take up more than 100GB of space.

It recently launched a device that allows 4K films to be streamed over the internet, but that will be impractical for people with slow internet access or accounts with data-use limits.

The tech firms do not directly refer to 4K movie sales in their press release, but rather talk of the wider "archive market".

"Optical discs have excellent properties to protect them against the environment, such as dust resistance and water resistance, and can also withstand changes in temperature and humidity when stored," they say.

"They also allow inter-generational compatibility between different formats, ensuring that data can continue to be read even as formats evolve. This makes them a robust medium for long-term storage of content."

Although the firms indicate the primary target market for the new technology will be businesses wishing to copy and preserve their data, there is also likely to be demand from the consumer market for higher capacity discs, even if sales of existing formats are waning.

The rise of streaming services such as Amazon's Lovefilm, Tesco's Blinkbox and Netflix coupled with the problem of internet piracy have eaten into disc-based television box set and movie sales.

There were 179 million disc-based videos sold in the UK last year, according to recently published figures from the British Film Institute (BFI). That marked a 14% drop on 2011.

They still accounted for more than £1.5bn of sales - more than six times the £243m generated by video-on-demand services over the same period. But VoD sales were 50% up on the year.

"For the foreseeable future, even with more advances in streaming, there will be a niche for discs," Russ Crupnick, a media analyst at consultants NPD told the BBC.

"But how large that is going to be is hard to say because it is going to be more about the collector and less about every day usage."

The demand for extra storage is also likely to be fuelled by the public's ability to generate its own ultra-high-definition footage.

JVC, Sony and Panasonic have all shown off prototype camcorders which they say will be targeted at the "prosumer" market, while GoPro already offers a budget option, albeit one that only records the format at 15 frames per second.

"The cheapest way to store lots of this material long term is going to be on an optical disc rather than a solid state drive in your laptop or tablet, or on SD cards," said Paul O'Donovan, digital video expert at the tech advisory firm Gartner.

"And they are more convenient if you want to send the video you shot to somebody.

"Imagine trying to send a 300 gigabyte file over the internet - it would take ages."

Special triple-layer 100GB BDXL Blu-ray discs already exist, offering an interim solution, and quad-level 128GB versions have also been promised. However, neither can be read by a normal player.