As discussed here previously, Seven’s lack of HD is RQLD is because of their limited technical capacity at the moment. To explain, he’s a simplified rundown of the step to get TV to your TV.
Step 1: Playout
In this step, a computer combines the TV shows, ads etc. into a continuous feed. It’s basically a big playlist, similar to how iTunes or whatever your favourite media played works, except it’s got some more features and has the ability to select not only files saved on the hard drive (such as ads and pre-recordeded shows), but it can also select live feeds (eg. from sporting events, TV studios etc).
A playlist needs to exist for each channel, eg. 7 Melbourne, 7two Melbourne, 7mate Melbourne, 7 Sydney, 7two Sydney etc. (but some parts can be shared between multiple channels to avoid double entry)
At Seven, this is all done in HD (with the exception that some of their news studios are only SD).
Step 2: Encoding
This is where the format and resolution are chosen - so, MPEG2 or MPEG4, SD or HD, and whatever bitrate they choose to run the channels at. This is done individually for each channel to be broadcast, and usually requires individual, expensive, equipment for each channel.
So Melbourne requires 5 encoders:
- 7 SD
- 7 HD
- 7two
- 7mate
- 7flix (this is actually done at MediaHub, not BCM due to the lack of capacity).
Their sixth channel, racing.com, only needs to be encoded once since no geographical differences mean all cities can share the same output.
Therefore, to add the HD channels for the 5 cities, they needed to add in 5 new encoders. To add HD to RQLD (including the Gold Coast) would require another 8 new encoders, plus the space to house these.
This is the same reason why Prime didn’t get PrimeHD until after they moved to MediaHub, and SCA9 didn’t get all their channels for a few weeks after the affiliation switch.
Step 3: Multiplexing & Transmission
The required encoded channels are “combined” into one 23mbps signal ready for transmission (known as multiplexing).
It is then sent by an IP-based network to the transmitter, where it is then broadcast from the transmitter and can be recieved by your TV.
(I believe this is the most common given it centralises most of the processing.)
Variations:
Sometimes the encoding and multiplexing happens in a different order.
For example, but the remote areas that use VAST, they have some terrestrial transmitters that broadcast using VAST as the input feed. In this case, they have number of VAST receivers at the transmitter site, then re-encode the signal on site as required (the signal was previously encoded for it be broadcast using VAST), the channels are multiplexed and transmitted. This setup works well because there’s next to no IP connectivity in many of these sites, but it does require any changes to be made individually at each site. This, along with the limited capacity of VAST are why regional WA doesn’t have the full suite of channels offered elsewhere by WIN and Prime.
So specifically for regional Queensland and why they can’t just turn on 7HD now.
These areas currently have:
- 7SD - MPEG2, SD - localised
- 7two - MPEG2, SD - localised
- 7mate - MPEG2, HD - localised
- 7flix - MPEG2, SD - statewide feed
- racing.com - MPEG4, SD - national feed
To add 7HD, the same as what the cities and Prime areas have, they need to add a new encoder to allow them to have a 6th channel - 7HD in MPEG4 HD. (x8 to cover each area, including Gold Coast).
An alternatives discussed here has been to switch 7mate and 7SD. However, this would mean that the main channel is also broadcast in MPEG2 HD, so anyone with an old TV/set-top box that can’t receive HD would no longer receive the channel at all.
Finally, this is why Seven are moving their playout
As discussed previously, there’s a plan for Seven and Nine to combine their playout into a shared facility in Sydney. (Time will tell if this is a new facility or Nine’s existing playout facility to Frenches Forrest).
Seven are going down this route because they realise that they need to replace some of their equipment and increase their capacity. This move will almost certainly result in RQLD getting 7HD and the playout of 7flix coming back “inhouse”. Unfortunately it’s just a matter of waiting until the move is done - Seven have indicated this will be April 2019.