After the BBC introduced new encoders on August 5, the bitrate on BBC HD dropped from 16Mbs to 9.7Mbs, a reduction of nearly 40%. Freesat viewers subsequently reported various problems with picture quality and sound on the channel, with some accusing the BBC of failing to deliver a truly high definition service.
In response, an expert Which? viewing panel ran a series of tests involving comparisons between archived pre-August BBC HD material and live broadcasts on Sky and Freesat. The footage was viewed on identical 40-inch HD TV sets.
After running like-for-like comparisons of a range of programming over a "lengthy viewing period", the panel found that any difference in picture quality between the new and old BBC HD broadcasts was "insignificant".
As recently outlined by BBC principal technologist Andy Quested, Which? also found that the perceived quality of BBC HD broadcasts differed from programme to programme, particularly dependent on whether the material was shot in the studio or outside.
"Even with the change in picture quality between programmes we assert that all BBC HD broadcasts are all of an HD quality," said Which? TV expert Michael Briggs.
"If there is any difference between the new HD broadcasts and the old HD broadcasts, then it is tiny, and smaller than the existing differences between any two HD programmes filmed in a studio or on location."
Earlier in the month, BBC HD head Danielle Nagler said that she wants to "draw a line" under the debate about picture quality on the channel.