After new encoders were introduced by the BBC on August 5, the bitrate on BBC HD dropped from 16Mbs to 9.7Mbs, a reduction of nearly 40%.
Digital Spy forum members subsequently reported a range of picture quality issues, including the appearance of compression artefacts, jittering on near-static scenes and problems with mixes and fades.
Eaton has therefore called on the BBC to return the quality of its flagship HD channel to pre-August levels, or he will submit a formal complaint to the BBC Trust.
After being contacted directly by Eaton in September, head of BBC HD Danielle Nagler said that the encoders were selected to improve picture quality on the BBC's "most challenging programmes", and also increase compatibility with satellite platforms.
She said that reported quality issues - primarily with the mixes and fades - were immediately acknowledged by her team, who have subsequently been working with the encoder supplier to resolve the problems going forward.
Unsatisfied with the response, Eaton sent another message to Keating, Nagler's superior, highlighting a perceived lack of engagement with the hundreds of forum posts on the BBC Internet Blog, DS and other platforms.
In his response, Keating stressed how "seriously" the issue of technical quality of BBC channels is taken at the corporation. He also acknowledged that viewers should always hold BBC HD to the highest standards.
Keating praised the expertise being demonstrated in many of the forum posts, but also gave his full backing to Nagler, saying that "no-one cares more deeply about maintaining, and improving the quality of service on our HD channel" than her team.
"This is a fast-moving area of technological change, where professionals at every point in the value-chain - from capture and production to playout and broadcast - are innovating all the time to deliver better results, and on occasion experimenting to find out what works and what doesn't," he said.
"This process of change and evolution is common to all broadcasters engaged in HD, though the BBC's channel carries wider range of genres and shooting styles than most channels in the market.
"On occasion, a change in technology may have unpredicted results: it's clear for instance that the August switch from the old-generation coders to the new set caused a number of visible problems on air. Swift action was taken to acknowledge these problems, and to address them."
Keating claimed that he has read and digested all the forum posts, and further acknowledged the BBC's duty to use its broadcast bandwidth in the most efficient way possible.
"Our goal is to keep pace with developments in compression technology to deliver an excellent HD service to licence fee payers while making best possible use of the spectrum available," he said.
"The new coders are designed to enable this process of evolution to continue with even better results than before, but I can give an absolute reassurance that we will monitor the results assiduously to ensure that there is no compromise to the channel's quality of output."
Keating also gave assurances that BBC principal technologist Andy Quested is currently considering the most recent forum posts on BBC HD picture quality, and will issue further correspondence imminently.