The BBC Trust has approved proposals to launch a high definition TV channel - but delayed its debut on Freeview.
Silent Witness is among the shows being aired on the trial HD channel
The trust concluded it was "essential" HD TV was made "universally available".
The channel will air on cable and satellite "as soon as possible" and on Freesat, the BBC's free-to-view digital satellite service, when it is launched.
Proposals for the Freeview service were put on hold because viewers might have been required to buy two new set-top boxes to receive the channel.
"We believe there is currently too great a risk of confusing customers due to the need for upgrades," said BBC Trustee Diane Coyle.
Freeview users would have needed to buy a new set-top box to receive an interim four-hour overnight service that had been suggested.
Because of proposed changes in the way Freeview is broadcast, however, they would have had to upgrade their equipment again when the full, nine-hour service became available.
The "mixed genre" HD channel will show programmes from across all of the BBC's stations and will not be a replication of BBC One.
A trial version is already running on satellite and cable, showing such programmes as Bleak House and Silent Witness.
The full channel will feature a nine-hour schedule from 1500 to midnight, with freedom to extend beyond those hours if necessary.
The proposed channel will be available on cable and satellite
Ms Coyle said the trust would consider the timing of the Freeview launch next spring, when there should be "greater clarity" on how much space will be available to broadcast the HD signals.
The announcement follows a public consultation on the proposals, which received the trust's provisional backing in September.
HD television is a new format that promises improved pictures and audio, with widescreen broadcasts.
Viewers wishing to take advantage of the new service will need a HD-compatible television.