I’ve been looking at the bit rates on the various multiplexes and I believe that the networks can fit in more HD broadcasts now without shutting down any legacy MPEG2 format.
My thinking is that a 720p HD MPEG4 broadcast would be suitable for a multichannel. Looking into the numbers, 720p needs fewer bits to be transmitted per second plus more importantly the progressive stream apparently compresses better. I think that a 2.5 - 2.8 Mbps 720p stream would provide a quality HD channel.
So if we took Nine’s multiplex in Brisbane tonight 9HD in 1080i is running at 3.26 Mbps.
The other channels are
9SD 4.0
9Go 3.3
9Gem 3.3
9Life 3.8
So all that needs to happen is 0.625 - 0.7 reduction in bit rate for each channel to give 2.5 - 2.8.
In the case of SBS, SBS HD is currently running 7.5 (MPEG2) so they could replace that with 3 x 720p HD channels without having to adjust the bit rates for any of the SD channels.
Are broadcasting encoders really good enough these days that you can broadcast three 720p MPEG2-HD channels on a multiplex at 2.5-3.0mbps without it becoming all pixelated/blurry every five seconds?
As I understand it, networks can accommodate 23 M/bits per second of data on each channel.
The streams you’ve listed there add up to approx 17.7 M/bits.
Can see you where the other 5.3 has gone?
Some small amounts of data might be taken up by closed captions and EPG info, but as I don’t think there’s any error correction used in DVB-T, there’s no slideshows (both of which accounts for space in DAB+ Radio), and there’s no EPG channel anymore.
Will that make a difference?
After they switch back are they going to have two 7bogans, 576i MPEG2 & 1080i MPEG4?
Of course I’d prefer 7HD remained and 7flix & 7bogan were MPEG4 (perhaps 720p?) but I don’t see Seven changing what they’re doing.
Personally I’d prefer to have Seven’s main channel here in Sydney on a permanent basis (even though not much of Seven’s programing appeals to me in general), but I suppose that 7Bogan…I mean, 7mate is “The Best Channel In The World Ever” and that any TV station with such a title deserves to be seen in full 1080i HD.
I hope they’re not airing that ‘best channel’ promo on the SD channel in Melbourne, etc!
Well no doubt I’ll hear/read on here the (justified) howls of protest when 7HD disappears again.
Of course I haven’t received any response to my complaint to Prime7 about the lack of 7HD (resulting in the AusOpen being shown in SD, nor from WIN about the monstrosity dubbed ‘Mappy’).
The sad thing is with 4k UHD TVs already being sold here not only is there almost no UHD content - and I gather than 1080 HD content looks…bad on UHD TVs (similar to SD on a HD TV I guess) - but most channels are still SD (I know Foxtel are doing better, and Netflix is great, but still…).
Sooner or later the networks will have to push MPEG4 a bit more (maybe next summer?), switch their least popular channels to it first (perhaps test it in a particular market), stick with it for more than a couple of months & see how little complaints there are, then the next least popular channel, etc. (Probably a bit of wishful thinking on the timing.)
Can confirm the 7HD guide goes to at least Thursday on my epg. I’m in perth. It could all mean nothing seven may switch to 7bogan HD straight after the tennis on Sunday night.
How hard is it really to have some sort of clarification ? Apparently it’s really hard.
