The companies join the BBC, ITV, Five and BT in committing to the project which, subject to approval by the BBC Trust, will create a next-generation platform for Freeview and Freesat.
The proposed venture will deliver television programmes and other online content to the living room over broadband, on-demand and subscription-free services.
With internet-connected TV set to be the next major technological development in broadcasting, Channel 4 believes Project Canvas is critical to the long-term future of subscription-free TV.
Over the last five years the TalkTalk Group has invested more than £1 billion in the broadband and the home phone market in the UK. The company launched ‘free broadband' in April 2006 and now covers more than 80% of the UK population with its Next Generation Network.
Gill Pritchard, director of strategy at Channel 4, said: ‘IPTV is set to become the next generation of TV and if Channel 4 is to continue to enhance its importance in a fully converged world it is key to be part of driving Project Canvas. We believe that Project Canvas is an important development that will bring considerable benefits to all viewers, increasing the accessibility of on-demand content for everyone, not just the technologically savvy.'
Project Canvas project director Richard Halton, speaking on behalf of partners BBC, ITV, Five and BT, said: ‘Project Canvas can help secure the future of free-to-air broadcasting, as well as create an opportunity for a wide range of public services and new commercial models to thrive through an open platform. We're delighted that Channel 4 and TalkTalk have joined the project.'