But every reason why non-DVB-T2 devices cannot decode those SD channels, which is the real point of needing at least one legacy DVB-T1 MUX for the foreseeable future.
This is what we don't want as there will be an ASO / DSO like situation ....
At the reallocation all muxes should go T2 ....
Which is about as far in the future that I can think about ....
Say the next ten years .....
This means that there is a single event which will last until a FOBTV UHD2 proposition hits us.
I think that OFCOM could give a change over timetable of say 6 months (which compaired with the last switch over is generous!), this would enable all other people to buy new equipmet at their lesure
Well that is a damn silly way of going about it. Much better to make DVB-T2 mandatory on all new equipment. France does this sort of thing. Why can't we?
We can and should very easily .... It just requires Vince Cable to do it .... But we need Freeview HD tick only ...
And I do not think the public would notice the lack of the Freeview tick equipment.
DTT is lagging roughly 10 years behind other platforms like Sky. They switched analogue off in 2001 with DTT in 2012. Sky HD started in 2006 with DTT HD starting at the end of 2009 although you would be hard pushed to find any equipment until 2010!
In response to a few of the posts: don't worry your pretty little heads about those of us in Freeview Lite areas. Anyone around here who gives a damn got Freesat or Sky years ago. Anyone who was vaguely thinking about moving back to terrestrial on the main set and who understands the current proposal is going to stick with satellite to get those extra HD channels at the end of this year, rather than on Freeview lite maybe 5 years later.
Freeview lite is for second TVs and people who don't care so much about channel choice or HD.
Remember that when doing your fantasy mux planning. Actually, I wish the real planners would remember that too - people in Freeview light areas would probably prefer to see ITV3+4, Dave, Yesterday and other Freeview-full channels before anything in HD. Heck, it would make it worth connecting an aerial even for Freesat viewers if some of those channels were on Freeview lite. I realise I've strayed into total fantasy now, before anyone points out the commercial realities of this.
btw, like other posters, I'm sure some of those future T2 muxes (post 2018) are going to be jam-packed with SD as well as HD. We might see some 720p too - you can squeeze that far more than 1080i. You don't have to use the full horizontal resolution of either. Looking forward to all the "they don't even look as good as full-SD" "HD" shopping channels!
In response to a few of the posts: don't worry your pretty little heads about those of us in Freeview Lite areas. Anyone around here who gives a damn got Freesat or Sky years ago. Anyone who was vaguely thinking about moving back to terrestrial on the main set and who understands the current proposal is going to stick with satellite to get those extra HD channels at the end of this year, rather than on Freeview lite maybe 5 years later.
Freeview lite is for second TVs and people who don't care so much about channel choice or HD.
Remember that when doing your fantasy mux planning. Actually, I wish the real planners would remember that too - people in Freeview light areas would probably prefer to see ITV3+4, Dave, Yesterday and other Freeview-full channels before anything in HD. Heck, it would make it worth connecting an aerial even for Freesat viewers if some of those channels were on Freeview lite. I realise I've strayed into total fantasy now, before anyone points out the commercial realities of this.
btw, like other posters, I'm sure some of those future T2 muxes (post 2018) are going to be jam-packed with SD as well as HD. We might see some 720p too - you can squeeze that far more than 1080i. You don't have to use the full horizontal resolution of either. Looking forward to all the "they don't even look as good as full-SD" "HD" shopping channels!
Cheers,
David.
you have a good point re 720p as it is a valid delivery methord of HD programming!
I suppose 960*720 instead of 1280*720 is what you are thinking could be used?
This would surely mean that for every full 1080i channel two reduced 960*720 720p channels could be broadcast! This would mean 10 'reduced' HD channels on just one of the com MUXs, meaning 30 altogether (unless the BBC need a slot as they will want a full 1080i slot!), this way they could convert all current SD channels to at least full 720*576i, or conver some to this reduced HD!
These 'reduced' 720P HD channels would have to have originated in 1080i or P though surely?
Could the SD channels on the T2 MUXs be of a higher horizontal resoultion that sees the pixles go squaire so say 1024*576 instead of 720*576, meaning HD TVs get a higher resoultion of SD than non HD TVs, when over HDMI that is!
This would only work for downscaled programs of course, but it would be a vast improvement!
No. DVB-T boxes would not support 1024x576i/25 video.
Oh sorry, I see what you mean. I still don't think it'd work - I doubt DVB-T2 boxes are capable or programmed to downscale 1024x576 to 720x576 for SD connections (e.g. SCART).
I don't know what the broadcast specs specifically are (in terms of what boxes have to support) but I bet it's very limited and wouldn't even allow 1024x576. 720p/50 is a decent compromise I suppose - channels using this could even say they were "HD", which is good for marketing.
you have a good point re 720p as it is a valid delivery methord of HD programming!
I suppose 960*720 instead of 1280*720 is what you are thinking could be used?
Yep. It's only a guess though - it's probably too sensible.
Unless OfCom stops them, there's nothing to say they can't use 544x576i with AVC at a super low bitrate (sub 1Mbps) if they just want something on there (e.g. more shopping channels).
It remains to be seen whether there's much demand for something between "the best that can be done" and "about the worst that can be done" in an all T2 world. Looking at DVB-T and DAB, channels seem to drift towards three quality levels - very good, truly abysmal, and just about acceptable. In a T2/HD world, 1920x1080i50 averaging ~8Mbps is the "very good", 544x576i50 averaging ~0.5Mbps is the truly abysmal - but whether "just about acceptable" is 720x576i50 at ~1Mbps, or 960x720p50 at ~3Mbps - I don't know. Maybe we'll see all four options.
page 62 = resolutions for SD (using AVC)
page 66 = resolutions for HD (using AVC)
1024x576 isn't supported.
Cheers,
David.
P.S. imagine the implications for choice on satellite when it transitions to S2 if SD channels are still provided. My guess is that only minority channels will remain in SD (just like only minority channels remain(ed) in 4:3).
page 62 = resolutions for SD (using AVC)
page 66 = resolutions for HD (using AVC)
1024x576 isn't supported.
Cheers,
David.
P.S. imagine the implications for choice on satellite when it transitions to S2 if SD channels are still provided. My guess is that only minority channels will remain in SD (just like only minority channels remain(ed) in 4:3).
OK but that list doesn't include 704x576, which is used on D3&4.
As for SD channels using AVC and DVB-T2, I'd like to see 1.5 Mbps for video as a minimum. It is the perfect opportunity to specify concrete minimum quality levels so we don't get the mess we have now.
Yep. It's only a guess though - it's probably too sensible.
Unless OfCom stops them, there's nothing to say they can't use 544x576i with AVC at a super low bitrate (sub 1Mbps) if they just want something on there (e.g. more shopping channels).
It remains to be seen whether there's much demand for something between "the best that can be done" and "about the worst that can be done" in an all T2 world. Looking at DVB-T and DAB, channels seem to drift towards three quality levels - very good, truly abysmal, and just about acceptable. In a T2/HD world, 1920x1080i50 averaging ~8Mbps is the "very good", 544x576i50 averaging ~0.5Mbps is the truly abysmal - but whether "just about acceptable" is 720x576i50 at ~1Mbps, or 960x720p50 at ~3Mbps - I don't know. Maybe we'll see all four options.
page 62 = resolutions for SD (using AVC)
page 66 = resolutions for HD (using AVC)
1024x576 isn't supported.
Cheers,
David.
P.S. imagine the implications for choice on satellite when it transitions to S2 if SD channels are still provided. My guess is that only minority channels will remain in SD (just like only minority channels remain(ed) in 4:3).
wow that list is an eye opener 640*720! or 960*1080! wow that would just be what happens on some channels I bet! Then the channel can clame to be HD but it would just be slightly better than SD if they use 640*720! although the resolution is the opisite way round! 640*720 vs 720*576!
So you're saying 720 x 576 is no better than 704 x 576? That's not what one would think logically.
It's essentially the same thing, the padding pixels are added with only the centre 704 pixels actually displayed. With 720x576, 8 padding pixels are added at each side during encoding, with 704x576, they are added during decoding.
How it is actually displayed will largely depend on how the equipment is set up to display it. Normally, with SD, the padding pixels would be lost in the overscan and not visible.
(This has been discussed before with some users commenting that their equipment displays the "full screen" with narrow black bars.)
The outer 16 pixels in a 720x576 image are supposed to be chopped off and are not part of the 4:3 or 16:9 active area. In terms of aspect ratio, 704x576 should be expanded to 1024x576 (16:9) with square pixels and 720x576 is meant to be expanded to 1050x576 with square pixels (if you're not doing cropping beforehand).
Still doesn't explain why 704x576 is missing from the list though, since that is used natively also.
It's essentially the same thing, the padding pixels are added with only the centre 704 pixels actually displayed. With 720x576, 8 padding pixels are added at each side during encoding, with 704x576, they are added during decoding.
How it is actually displayed will largely depend on how the equipment is set up to display it. Normally, with SD, the padding pixels would be lost in the overscan and not visible.
(This has been discussed before with some users commenting that their equipment displays the "full screen" with narrow black bars.)
The outer 16 pixels in a 720x576 image are supposed to be chopped off and are not part of the 4:3 or 16:9 active area. In terms of aspect ratio, 704x576 should be expanded to 1024x576 (16:9) with square pixels and 720x576 is meant to be expanded to 1050x576 with square pixels (if you're not doing cropping beforehand).
Still doesn't explain why 704x576 is missing from the list though, since that is used natively also.
The 16 pixel padding is annoying when displayed on a HD screen upscaled to 1080i! as you know its a 16:9 image thats been squashed a bit, so its not even OAR any more!
Why is this padding added! why wasnt the image just sampled as 720 pixels wide? instead of being sampled as 704 and padded out to 720 that is?
Still doesn't explain why 704x576 is missing from the list though, since that is used natively also.
It is covered in note 3. The list is luminance resolutions easily upscaled using a simple ratio. Note 3 is the recommendation for upscaling 704 and 352 luminance resolutions.
The 16 pixel padding is annoying when displayed on a HD screen upscaled to 1080i! as you know its a 16:9 image thats been squashed a bit, so its not even OAR any more!
Why is this padding added! why wasnt the image just sampled as 720 pixels wide? instead of being sampled as 704 and padded out to 720 that is?
704x576 is the active area, your equipment should still calculate the aspect ratio based on the active area. Don't expect all equipment to do it correctly.
As for why they use 704, there's a relatively small capacity saving compared to 720 but there's no shortage of capacity on D3&4. You could try asking D3&4 but I wouldn't really expect them to reply.
704x576 is the active area, your equipment should still calculate the aspect ratio based on the active area. Don't expect all equipment to do it correctly.
As for why they use 704, there's a relatively small capacity saving compared to 720 but there's no shortage of capacity on D3&4. You could try asking D3&4 but I wouldn't really expect them to reply.
704 res appears to work better over HDMI than 720 as my TV just displays what it thinks to be 1080i anyway. Well thats what my Sky+HD box does anyway.
I find its when watching BBC's SD channels upscaled to 1080i that there is a problem! although my local news is ok so they must do something to eliminate the padding!
Switching off SD would be a disaster. There are loads of SD TVs and monitors still in use. What will happen to them if TV becomes HD-only? An utterly waste of good/trustworthy equipment we've been using for years. They just want our money for new HD equipment.
Switching off SD would be a disaster. There are loads of SD TVs and monitors still in use. What will happen to them if TV becomes HD-only? An utterly waste of good/trustworthy equipment we've been using for years. They just want our money for new HD equipment.
As for why they use 704, there's a relatively small capacity saving compared to 720 but there's no shortage of capacity on D3&4. You could try asking D3&4 but I wouldn't really expect them to reply.
Well there really is no point using 720x576 over 704x576 since the extra pixels are meant to be cropped. If using non-standard equipment (e.g. a PC), you can gain those extra 16 columns of pixels if they aren't blank but it's not exactly experience-altering.
Switching off SD would be a disaster. There are loads of SD TVs and monitors still in use. What will happen to them if TV becomes HD-only? An utterly waste of good/trustworthy equipment we've been using for years. They just want our money for new HD equipment.
all HD receiving boxes have a Scart or composite output on them with HD channels downscaled for that output! So anyone with an old SD set will still be able to watch in SD! where there might be a issue is with any boxes that dont have RF output in analouge SD, but some boxes should do that still!
Well there really is no point using 720x576 over 704x576 since the extra pixels are meant to be cropped. If using non-standard equipment (e.g. a PC), you can gain those extra 16 columns of pixels if they aren't blank but it's not exactly experience-altering.
yes I wish 704 was the res that channels used or that any SD channel originating in HD would utilise the full 720 columns of SD for a better quality image!
Comments
This is what we don't want as there will be an ASO / DSO like situation ....
At the reallocation all muxes should go T2 ....
Which is about as far in the future that I can think about ....
Say the next ten years .....
This means that there is a single event which will last until a FOBTV UHD2 proposition hits us.
We can and should very easily .... It just requires Vince Cable to do it .... But we need Freeview HD tick only ...
And I do not think the public would notice the lack of the Freeview tick equipment.
While Ofcom could speed up DSO 2 they won't.
Freeview lite is for second TVs and people who don't care so much about channel choice or HD.
Remember that when doing your fantasy mux planning.
btw, like other posters, I'm sure some of those future T2 muxes (post 2018) are going to be jam-packed with SD as well as HD. We might see some 720p too - you can squeeze that far more than 1080i. You don't have to use the full horizontal resolution of either. Looking forward to all the "they don't even look as good as full-SD" "HD" shopping channels!
Cheers,
David.
you have a good point re 720p as it is a valid delivery methord of HD programming!
I suppose 960*720 instead of 1280*720 is what you are thinking could be used?
This would surely mean that for every full 1080i channel two reduced 960*720 720p channels could be broadcast! This would mean 10 'reduced' HD channels on just one of the com MUXs, meaning 30 altogether (unless the BBC need a slot as they will want a full 1080i slot!), this way they could convert all current SD channels to at least full 720*576i, or conver some to this reduced HD!
These 'reduced' 720P HD channels would have to have originated in 1080i or P though surely?
Read my post properly I said T2 meaning DVB-T2, not DVB-T1!
I don't know what the broadcast specs specifically are (in terms of what boxes have to support) but I bet it's very limited and wouldn't even allow 1024x576. 720p/50 is a decent compromise I suppose - channels using this could even say they were "HD", which is good for marketing.
Unless OfCom stops them, there's nothing to say they can't use 544x576i with AVC at a super low bitrate (sub 1Mbps) if they just want something on there (e.g. more shopping channels).
It remains to be seen whether there's much demand for something between "the best that can be done" and "about the worst that can be done" in an all T2 world. Looking at DVB-T and DAB, channels seem to drift towards three quality levels - very good, truly abysmal, and just about acceptable. In a T2/HD world, 1920x1080i50 averaging ~8Mbps is the "very good", 544x576i50 averaging ~0.5Mbps is the truly abysmal - but whether "just about acceptable" is 720x576i50 at ~1Mbps, or 960x720p50 at ~3Mbps - I don't know. Maybe we'll see all four options.
Here you go...
http://www.etsi.org/deliver/etsi_ts/101100_101199/101154/01.11.01_60/ts_101154v011101p.pdf
page 62 = resolutions for SD (using AVC)
page 66 = resolutions for HD (using AVC)
1024x576 isn't supported.
Cheers,
David.
P.S. imagine the implications for choice on satellite when it transitions to S2 if SD channels are still provided. My guess is that only minority channels will remain in SD (just like only minority channels remain(ed) in 4:3).
As for SD channels using AVC and DVB-T2, I'd like to see 1.5 Mbps for video as a minimum. It is the perfect opportunity to specify concrete minimum quality levels so we don't get the mess we have now.
wow that list is an eye opener 640*720! or 960*1080! wow that would just be what happens on some channels I bet! Then the channel can clame to be HD but it would just be slightly better than SD if they use 640*720! although the resolution is the opisite way round! 640*720 vs 720*576!
Yes but it's just 720x576 without the "padding" pixels (see note 3).
So you're saying 720 x 576 is no better than 704 x 576? That's not what one would think logically.
It's essentially the same thing, the padding pixels are added with only the centre 704 pixels actually displayed. With 720x576, 8 padding pixels are added at each side during encoding, with 704x576, they are added during decoding.
How it is actually displayed will largely depend on how the equipment is set up to display it. Normally, with SD, the padding pixels would be lost in the overscan and not visible.
(This has been discussed before with some users commenting that their equipment displays the "full screen" with narrow black bars.)
Still doesn't explain why 704x576 is missing from the list though, since that is used natively also.
The 16 pixel padding is annoying when displayed on a HD screen upscaled to 1080i! as you know its a 16:9 image thats been squashed a bit, so its not even OAR any more!
Why is this padding added! why wasnt the image just sampled as 720 pixels wide? instead of being sampled as 704 and padded out to 720 that is?
It is covered in note 3. The list is luminance resolutions easily upscaled using a simple ratio. Note 3 is the recommendation for upscaling 704 and 352 luminance resolutions.
704x576 is the active area, your equipment should still calculate the aspect ratio based on the active area. Don't expect all equipment to do it correctly.
As for why they use 704, there's a relatively small capacity saving compared to 720 but there's no shortage of capacity on D3&4. You could try asking D3&4 but I wouldn't really expect them to reply.
704 res appears to work better over HDMI than 720 as my TV just displays what it thinks to be 1080i anyway. Well thats what my Sky+HD box does anyway.
I find its when watching BBC's SD channels upscaled to 1080i that there is a problem! although my local news is ok so they must do something to eliminate the padding!
A box to downscale HD channels?
Well there really is no point using 720x576 over 704x576 since the extra pixels are meant to be cropped. If using non-standard equipment (e.g. a PC), you can gain those extra 16 columns of pixels if they aren't blank but it's not exactly experience-altering.
all HD receiving boxes have a Scart or composite output on them with HD channels downscaled for that output! So anyone with an old SD set will still be able to watch in SD! where there might be a issue is with any boxes that dont have RF output in analouge SD, but some boxes should do that still!
yes I wish 704 was the res that channels used or that any SD channel originating in HD would utilise the full 720 columns of SD for a better quality image!