DStv announced towards the end of August 2012 that it would be offering a number of new HD channels that are simulcasts of new and existing SD channels.
These channels would all broadcast 1080i HD content in the 1080i format using MPEG–4 AVC High Profile, MultiChoice told MyBroadband.
Broadcasting in 1080p would need more than double the “net pixel bit-rate” than the 720p or 1080i formats, they explained.
Both 1080i (interlaced scan) and 1080p (progressive scan) are regarded as high definition (HD) video resolutions. The differences between the two standards lie in the way individual frames of video are composed.
In the case of 1080i, images are interlaced into alternating rows of pixels (horizontal lines), and a frame is composed of two fields made up of two 1920×540 pixels each. A frame of 1080p video contains 1920×1080 pixels, with rows non-interlaced.
MultiChoice said that all digital content they broadcast is delivered to them by the content producer as compressed files using industry standard compression suitable for the purpose of content contribution.
“Various types are used depending on the choice of the content owner/originator,” MultiChoice said. “Uncompressed digital content contribution is not feasible due to the extremely high data rates involved.”
Contributed content is then loaded into DStv’s systems and distributed using their satellite platform in a compressed video stream.
The purpose of compression, MultiChoice said, is to reduce the output data rate to keep a balance between data rate and picture quality.