A Japanese telecoms company is carrying out tests to try to prove 4K-resolution video can be streamed over the internet to television set-top boxes.
NTT West is hosting the trial - which runs until Friday - and says it believes it is the first of its kind.
A new video compression standard is being used to reduce the amount of data that needs to be transmitted.
4K broadcasts offer four times the amount of detail as 1080p high-definition content.
Compressing technologies allow broadcasters to transmit material using much less data than would otherwise be required while minimising the loss of picture quality.
With regard to video, instead of sending data describing each pixel of each frame as if it were a standalone entity, a variety of algorithms are used to analyse how colour is distributed across each image and what changes occur between each frame.
This is then used to allow redundant information to be discarded, providing instead only the information needed to reconstruct a sequence based on an understanding of how each pixel and frame are related to each other.
At present the H.264/MPEG-4 codec is commonly used to broadcast digital TV - including the UK's Freeview HD and Sky HD satellite services - as well as the vast majority of video clips on the web.
In January the International Telecommunication Union (ITU), a UN agency, approved a new format to succeed it called the H.265 High Efficiency Video Coding (HEVC) standard.
It allows 4K and 1080p videos to be streamed using roughly half the bit rate, meaning half as much data needs to be transmitted, thanks to the use of more advanced algorithms.
The ITU said it should meet the needs of broadcasters for "the next decade".
Although 4K ultra-high-definition televisions are already on the market, content is scarce and most owners have relied on the sets' ability to upscale existing HD signals.
Japan plans to become the first country to broadcast 4K programming over satellite from 2014, in time for the football World Cup.
But the ability to stream ultra-high-definition video over the net would open the door to other services.