The decoders will be capable of receiving both standard and high-definition (up to 1080p) broadcasts—with support for widescreen broadcasts—and must specifically ignore all services originating from non-terrestrial digital services. It’s unlikely that South African broadcasters will offer highly bandwidth-intensive 1080p channels.
Widescreen high-definition broadcasts will be “down-converted” to standard definition for television sets that don’t support it and displayed in a 16:9 “letterbox” format on 4:3 displays. The decoder will allow viewers to display the material in a letterbox format within a 4:3 frame or perform a 4:3 “centre cut-out” on the broadcast material and present this full-frame within the 4:3 display.
An on-graphics plane and on-screen display information will use the 4:3 aspect ratio, regardless of the video aspect ratio.
‘Future use’
According to the draft spec, the decoder must be able to receive audio signals of up to 5.1 surround sound and output at least two-channel PCM stereo.
In terms of outputs, the decoder will offer a composite video output port on an RCA socket and an HDMI port. There’s also a single USB port (for “future use”) in the draft spec.
The decoder will also feature an “RF bypass” system so that consumers can continue to watch analogue broadcasts during the “dual-illumination” period when both analogue and digital television will coexist in South Africa.
The draft spec says South Africa will use MPEG-4 coding for video and will use 8MHz channel spacing in the VHF and UHF bands and will be capable of receiving broadcasts in chunks of spectrum from 174MHz to 862MHz. The MHEG-5 standard will be used to provide interactive services, including teletext-like services.
All eleven of South Africa’s official languages will be supported on the decoder and offer subtitles if these are made available by a broadcaster.
The set-top box will have a minimum of 64MB of flash memory and 256MB of RAM, the draft spec says. The memory specification has been chosen to allow for the lowest component price, it says.
The unit will draw a maximum of 10W of electricity during normal operation, 6W when in active standby and 3W when in passive standby. Its front panel will have “P+” and “P-” programme selector buttons, “V+” and “V-” volume buttons and a standby/on button.
