Freeview HD sound problem solved

The BBC says it’s found a solution to the sound problem that has been affecting some Freeview HD users.
There have been reports by some Freeview HD viewers of sound dropouts on certain Freeview HD channels. Devices from Samsung and Toshiba were prone to the sound problem, this affected most of the PSB HD channels, BBC One HD, BBC Two HD, ITV/STV/UTV HD, Channel 4 HD and CBBC HD.

Following an investigation by the BBC and appeals from the public for assistance in identifying all the devices that were experiencing the problem, the BBC now says it’s in a position to make some changes that will help the affected devices.

The changes will be rolled out by the BBC on a region-by-region basis, starting in Scotland, Wales, Northern Ireland and London.

Manufacturersof the affected devices are planning their own software updates to provide a long-term solution to the problem, although the BBC believes these updates may still be a few weeks away.

The BBC said:
“Rolling out regionally will enable us to monitor the impact, just in case we need to reverse the changes, if unexpected problems occur. Assuming it works successfully, we will roll out to the rest of the country in the next couple of weeks”

For the first time, the BBC has revealed what caused the problem: perceptual noise substitution or PNS, which under certain circumstances was being used by their encoders.

Explaining the technical side, the BBC said:
“PNS is part of the MPEG4 AAC specification which the UK D-Book* references. Our encoders have always been capable of using PNS but a recent update meant that PNS could be selected by the audio encoder at the audio bit rates used on Freeview.”