It's bad enough the BBC often screen a 4:3 programme in a 16:9 frame - so on boxes like my Sagem the ratio doesn't switch automatically from 16:9 to 4:3 meaning you get black bars all around - but lately I've noticed with BBC2 films (the films this afternoon being an example!) they put a 16:9 picture in a 4:3 frame in a 16:9 frame.
Ridiculous - ITV, C4 (especially) and five manage ratio switching properly, why can't the BBC - the corporation that's suppost to be at the forefront of the digital revolution!
That's awful. It's not just the fact that you get black bars all round, the resolution is reduced too, so you get a crap picture if you try to zoom in with your tv. I can't see this being a deliberate thing, it must've been a human error when programming some bit of kit I suppose.
When i watch news 24 and they do a headlines update, my tv briefly changes to 4:3 then switches back to 16:9 for every headline picture they show. Its really odd.
When i watch news 24 and they do a headlines update, my tv briefly changes to 4:3 then switches back to 16:9 for every headline picture they show. Its really odd.
It's a fault at the BBC caused by erroneous widescreen switching signalling on Line 23 leaking into the broadcast chain. Most digital TV receivers blank this line - but not all do (Sky+ boxes, Panasonic Sky boxes and a few Freeeview boxes don't)
It's bad enough the BBC often screen a 4:3 programme in a 16:9 frame - so on boxes like my Sagem the ratio doesn't switch automatically from 16:9 to 4:3 meaning you get black bars all around - but lately I've noticed with BBC2 films (the films this afternoon being an example!) they put a 16:9 picture in a 4:3 frame in a 16:9 frame.
Ridiculous - ITV, C4 (especially) and five manage ratio switching properly, why can't the BBC - the corporation that's suppost to be at the forefront of the digital revolution!
The BBC broadcast on DTT permanently in 16:9 - all 4:3 material is broadcast in 12P16 (4:3 pillarbox in a 16:9 frame). Almost all DTT receivers should pick up the accompanying AFDs - active format descriptors - that indicate the broadcast only contains 4:3 material (triggering a zoom if required). The AFDs are filtered by the national presentation areas (something ITV doesn't have to cope with) so occasional are incorrect in the nations (less so in England - though it is possible for an English region to have a "stuck" AFD historically)
The problem this afternoon is caused by the BBC showing old transfers of widescreen films which were transferred before the BBC went widescreen. It is often not the BBC's fault - the only copy of the films available for transmission is letterboxed 4:3 - with the film not available for re-transfer by the BBC.
Thus the transmission tape is 4:3 - but contains a letterbox widescreen image. Quite correctly the BBC broadcast this as if it is 4:3. (This is most common with older foreign films which have subtitles burned in) Channel Four have also done this in the past - and Film Four do on occasion. ITV don't - but mainly because they show different kinds of stuff.
(The other reason is a cock-up in Scotland, Ireland or Wales causing the analogue network feed being broadcast on digital outlets - though this is less likely these days)
It's bad enough the BBC often screen a 4:3 programme in a 16:9 frame - so on boxes like my Sagem the ratio doesn't switch automatically from 16:9 to 4:3 meaning you get black bars all around - but lately I've noticed with BBC2 films (the films this afternoon being an example!) they put a 16:9 picture in a 4:3 frame in a 16:9 frame.
Ridiculous - ITV, C4 (especially) and five manage ratio switching properly, why can't the BBC - the corporation that's suppost to be at the forefront of the digital revolution!
The BBC broadcast on DTT permanently in 16:9 - all 4:3 material is broadcast in 12P16 (4:3 pillarbox in a 16:9 frame). Almost all DTT receivers should pick up the accompanying AFDs - active format descriptors - that indicate the broadcast only contains 4:3 material (triggering a zoom if required). The AFDs are filtered by the national presentation areas (something ITV doesn't have to cope with) so occasional are incorrect in the nations (less so in England - though it is possible for an English region to have a "stuck" AFD historically)
The problem this afternoon is caused by the BBC showing old transfers of widescreen films which were transferred before the BBC went widescreen. It is often not the BBC's fault - the only copy of the films available for transmission is letterboxed 4:3 - with the film not available for re-transfer by the BBC.
Thus the transmission tape is 4:3 - but contains a letterbox widescreen image. Quite correctly the BBC broadcast this as if it is 4:3. (This is most common with older foreign films which have subtitles burned in) Channel Four have also done this in the past - and Film Four do on occasion. ITV don't - but mainly because they show different kinds of stuff.
(The other reason is a cock-up in Scotland, Ireland or Wales causing the analogue network feed being broadcast on digital outlets - though this is less likely these days)
It's impossible in Northern Ireland - there is no analogue network incoming feed here anymore.
The BBC broadcast on DTT permanently in 16:9 - all 4:3 material is broadcast in 12P16 (4:3 pillarbox in a 16:9 frame). Almost all DTT receivers should pick up the accompanying AFDs - active format descriptors - that indicate the broadcast only contains 4:3 material (triggering a zoom if required). The AFDs are filtered by the national presentation areas (something ITV doesn't have to cope with) so occasional are incorrect in the nations (less so in England - though it is possible for an English region to have a "stuck" AFD historically)
Not quite correct though, at least in the case of Wales - and as far as I know everyone else in the network. 4:3 material is treated thus...
It comes in on tape as full-frame 4:3. It's then passed through an ARC to pillarbox it onto a 16:9 raster on acquisition. This is purely because all transmission suites operate in 16:9 format.
On transmission there are two dynamically switched ARCs in the output chains - one for digital, one for analogue. As long as the correct AFD is set via the transmission automation (by flagging a GPI on that particular schedule event) both those ARCs will switch to centre cut-out and the AFD will be set at 12-12- (not 12-16-). Thus the left and right bars (the pillarbox) are NOT actually transmitted, and your DiTV or STB will know that the picture is 4:3. All that's transmitted on DSat and DTT is the 4:3 picture area.
Now, if like me you can't stand stretched aspect ratios and your widescreen TV is set up to display 4:3 pictures as a pillarbox, then your TV will insert the black bars left and right. On the other hand, if you like stretchy-vision, you'll be able to stretch it to fill the glass. If it was flagged with a 12-16- AFD you wouldn't be able to do this as we'd be transmitting the bars and they'd be part of the active field. You'd have to set your STB to centre cut-out (i.e. as if it was feeding a 4:3 set) in order to stretch the picture, and this would obviously foul up any 16:9FHA material unless you were prepared to keep changing the setting.
noggin posted:
The problem this afternoon is caused by the BBC showing old transfers of widescreen films which were transferred before the BBC went widescreen. It is often not the BBC's fault - the only copy of the films available for transmission is letterboxed 4:3 - with the film not available for re-transfer by the BBC.
Thus the transmission tape is 4:3 - but contains a letterbox widescreen image. Quite correctly the BBC broadcast this as if it is 4:3. (This is most common with older foreign films which have subtitles burned in) Channel Four have also done this in the past - and Film Four do on occasion. ITV don't - but mainly because they show different kinds of stuff.)
Quite true. Much of this material only exists as a 14:9 or 16:9 letterbox on a 4:3 raster. This would be acquired and transmitted as explained above. If you watch it pillarboxed on a widescreen set you'll see that the bars top and bottom are transmitted as part of the picture and are composed of 'black light' - that is to say your telly will be producing them and they'll be grey and luminescent. The pillarbox left and right should be completely black, because the set will only be scanning the centre area which composes the active field as described by the transmitted AFD.
noggin posted:
(The other reason is a cock-up in Scotland, Ireland or Wales causing the analogue network feed being broadcast on digital outlets - though this is less likely these days)
No chance of that whatsoever in Cardiff either. Although we do still have analogue feeds of Net 1 and Net2 they no longer go anywhere near the transmission suites, and are only used for overnight sustaining. The Wales analogue services are sustained from approx 5.45am until closedown on the digital feed going through the aforementioned dynamic ARC.
The BBC broadcast on DTT permanently in 16:9 - all 4:3 material is broadcast in 12P16 (4:3 pillarbox in a 16:9 frame). Almost all DTT receivers should pick up the accompanying AFDs - active format descriptors - that indicate the broadcast only contains 4:3 material (triggering a zoom if required). The AFDs are filtered by the national presentation areas (something ITV doesn't have to cope with) so occasional are incorrect in the nations (less so in England - though it is possible for an English region to have a "stuck" AFD historically)
Not quite correct though, at least in the case of Wales - and as far as I know everyone else in the network. 4:3 material is treated thus...
It comes in on tape as full-frame 4:3. It's then passed through an ARC to pillarbox it onto a 16:9 raster on acquisition. This is purely because all transmission suites operate in 16:9 format.
On transmission there are two dynamically switched ARCs in the output chains - one for digital, one for analogue. As long as the correct AFD is set via the transmission automation (by flagging a GPI on that particular schedule event) both those ARCs will switch to centre cut-out and the AFD will be set at 12-12- (not 12-16-). Thus the left and right bars (the pillarbox) are NOT actually transmitted, and your DiTV or STB will know that the picture is 4:3. All that's transmitted on DSat and DTT is the 4:3 picture area.
Sorry Steve D - that isn't the case for DTT AIUI - and certainly not the case for DTT via Crystal Palace!
Only the DSat feed is fed through an ARC - the DTT feed is (and always has been) permanently 16:9 format (no ARC in the way) - with broadcast AFDs triggering DTT set top boxes to drop into 12F12 mode, doing a (cheap) ARC themselves from 12P16 to 12F12.
PC DVB-T cards (like mine) don't all do this - and recordings made of BBC channels contain the "black video" present in the "P" bits of 12P16. This is mildly annoying when you master a DVD from an off-air MPEG2 recording without decompressing and recompressing - you end up with "video" black bars left and right.
AIUI Cardiff isn't different to any other BBC Nation or Region in this regard?
Happy to be proved wrong - but permanent 16:9 + AFD control of the STB is the BBC DTT standard (and was also the case with Five until they changed their transmission arrangements recently) Initially the BBC didn't have AFD broadcast (neither did they have ARCs in their Sky feed) - and just broadcast permanent 16:9 with no switching information. London got the ARCs in their DSat feeds long before the Nations ISTR. (These are the days of the infamous "BBC Choice Scotland" dogs...)
AUII AFDs aren't supported by EVERY DTT box - though all Freeview badged boxes have to be compliant - there are some old ONDigital boxes that didn't receive software upgrades potentially and when configured for letterbox output in 4:3 they deliver a postage stamp rather than a full-frame 4:3 image when 12P16 broadcasts (with a 12P16 AFD) are broadcast.
The ARCs are only present in the BBC One and Two digital DSat feeds (as Sky receivers don't support AFDs) as this can only be broadcast 12F12 or 16F16 - the digital DTT feed is encoded pre-ARC I believe. The ARC in the analogue chain is there for 12F12, 14L12 or 16L12 broadcast of 12P16 or 16F16 sources as you say.
This caused a problem for the BBC when they moved to BBC One English regions on DSat - as they had to put an ARC down-stream of the opt-chain to implement 12P16 to 12F12 conversion but prior to the DSat MPEG2 encoding in every region. (This ARC wasn't needed in the DTT chain as 12P16 is broadcast with an AFD)
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The BBC broadcast on DTT permanently in 16:9 - all 4:3 material is broadcast in 12P16 (4:3 pillarbox in a 16:9 frame). Almost all DTT receivers should pick up the accompanying AFDs - active format descriptors - that indicate the broadcast only contains 4:3 material (triggering a zoom if required). The AFDs are filtered by the national presentation areas (something ITV doesn't have to cope with) so occasional are incorrect in the nations (less so in England - though it is possible for an English region to have a "stuck" AFD historically)
Not quite correct though, at least in the case of Wales - and as far as I know everyone else in the network. 4:3 material is treated thus...
It comes in on tape as full-frame 4:3. It's then passed through an ARC to pillarbox it onto a 16:9 raster on acquisition. This is purely because all transmission suites operate in 16:9 format.
On transmission there are two dynamically switched ARCs in the output chains - one for digital, one for analogue. As long as the correct AFD is set via the transmission automation (by flagging a GPI on that particular schedule event) both those ARCs will switch to centre cut-out and the AFD will be set at 12-12- (not 12-16-). Thus the left and right bars (the pillarbox) are NOT actually transmitted, and your DiTV or STB will know that the picture is 4:3. All that's transmitted on DSat and DTT is the 4:3 picture area.
Sorry Steve D - that isn't the case for DTT AIUI - and certainly not the case for DTT via Crystal Palace!
Only the DSat feed is fed through an ARC - the DTT feed is (and always has been) permanently 16:9 format (no ARC in the way) - with broadcast AFDs triggering DTT set top boxes to drop into 12F12 mode, doing a (cheap) ARC themselves from 12P16 to 12F12.
PC DVB-T cards (like mine) don't all do this - and recordings made of BBC channels contain the "black video" present in the "P" bits of 12P16. This is mildly annoying when you master a DVD from an off-air MPEG2 recording without decompressing and recompressing - you end up with "video" black bars left and right.
AIUI Cardiff isn't different to any other BBC Nation or Region in this regard?
Happy to be proved wrong - but permanent 16:9 + AFD control of the STB is the BBC DTT standard (and was also the case with Five until they changed their transmission arrangements recently) Initially the BBC didn't have AFD broadcast (neither did they have ARCs in their Sky feed) - and just broadcast permanent 16:9 with no switching information. London got the ARCs in their DSat feeds long before the Nations ISTR. (These are the days of the infamous "BBC Choice Scotland" dogs...)
AUII AFDs aren't supported by EVERY DTT box - though all Freeview badged boxes have to be compliant - there are some old ONDigital boxes that didn't receive software upgrades potentially and when configured for letterbox output in 4:3 they deliver a postage stamp rather than a full-frame 4:3 image when 12P16 broadcasts (with a 12P16 AFD) are broadcast.
The ARCs are only present in the BBC One and Two digital DSat feeds (as Sky receivers don't support AFDs) as this can only be broadcast 12F12 or 16F16 - the digital DTT feed is encoded pre-ARC I believe. The ARC in the analogue chain is there for 12F12, 14L12 or 16L12 broadcast of 12P16 or 16F16 sources as you say.
This caused a problem for the BBC when they moved to BBC One English regions on DSat - as they had to put an ARC down-stream of the opt-chain to implement 12P16 to 12F12 conversion but prior to the DSat MPEG2 encoding in every region. (This ARC wasn't needed in the DTT chain as 12P16 is broadcast with an AFD)
Well, I can't speak for network via Crystal Palace, but from Cardiff the split in the digital chain to feed DSat and DTT is - as I have always understood it - downstream of the dynamic ARC. There has though recently been a re-working of the digital transmission chain to enable a different feed to DSat and DTT, so it's possible that it might have changed during that work. That's caused another problem in that in the days of the BBC Choice Wales DOG, it was inserted into the digital transmission chain downstream of the pres. suite. In order for it now to appear on both platforms the BBC 2W DOG is across suite output.
You are correct that the Nations' widescreen switching project was later than the network one, which meant that in the early days of the digital project, when we were opted out of the network (and thereby stripping any AFD data from the stream) the output was permenantly flagged as 16:9 giving the postage stamp, or 'floater' with letterboxed material.
I have a very old ONdigital box and pick up DTT from Wenvoe, and when I had a 4:3 set and had the box configured to letterbox widescreen material, it would (post widescreen-switching in Wales) always oblige and fill my 4:3 screen with 4:3 material. Likewise now I have a 16:9 set, although I always choose to watch 4:3 material pillarboxed, I am quite able to stretch it to fill the screen if I choose. However, I am unable to do this with material in 4:3 format flagged as 16:9 from other channels - I have now and again experimented with zooming up letterboxed material, but don't like the results very much!
However, I'm perfectly happy to bow to your far superior knowledge of the technical details. The point I was making is that the BBC do not actively transmit 4:3 material as 16:9 unless there's been a cock-up. To the best of their ability - and allowing for any such necessary compromise in the transmission chain over which transmission staff have no control - presentation staff in both Network and Nations will always do their best to send out a picture to each platform in the format which will give the optimum resulting picture.
As we have seen from this thread though, no matter how hard you try to deliver the correct shape of picture to the viewer, there is no legislating for what they do with it once they've received it!!
Well, I can't speak for network via Crystal Palace, but from Cardiff the split in the digital chain to feed DSat and DTT is - as I have always understood it - downstream of the dynamic ARC.
As I have mentioned in previous posts I don't believe this to be the case. AIUI the ARCs are only present in the DSat and analogue feeds - with none ever introduced in to the DTT feed because the DTT platform supports receiver interpretation of AFDs. (It was part of the UK DVB-T implementation standard - though not implemented at launch as receiver manufacturers didn't get across things quickly enough? ITV/C4 didn't go down the AFD route) Thus BBC 4:3 material on DTT is always broadcast in 12P16 - but the AFD accompanying it triggers AFD compliant set top boxes (all Freeview plus almost all OnDigital boxes that got software upgrades in the time of OnDigital/ITVDigital) to drop into 4:3 centre-cut out mode dynamically.
Similarly, newer Freeview branded boxes (my Mum's Sony and my Pace DTVA for example) when receiving 16F16 but configured for 4:3 letterbox output, will output 16L12 or 14L12 depending upon the AFD accompanying (which usually matches analogue) The use of AFDs is a major benefit DTT has over DSat in the UK implementation.
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There has though recently been a re-working of the digital transmission chain to enable a different feed to DSat and DTT, so it's possible that it might have changed during that work.
As I said previously - I would be surprised if this was the case - it would mean BBC Three and Four worked differently to One and Two in Wales wouldn't it? (BBC Three and Four are presumably just MPEG2 decoded and recoded for statmuxing for DTT in Cardiff - they wouldn't have dynamic ARCs in the DTT chain for these would they? The feeds of Three/CBBC and Four/CBeebies into Cardiff are presumably the same as I receive in London via CP - which are permanent 16:9 16F16/12P16 with AFDs)
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That's caused another problem in that in the days of the BBC Choice Wales DOG, it was inserted into the digital transmission chain downstream of the pres. suite. In order for it now to appear on both platforms the BBC 2W DOG is across suite output.
You are correct that the Nations' widescreen switching project was later than the network one, which meant that in the early days of the digital project, when we were opted out of the network (and thereby stripping any AFD data from the stream) the output was permenantly flagged as 16:9 giving the postage stamp, or 'floater' with letterboxed material.
Initially none of the BBC DSat outlets had any dynamic ARCs! All outlets were permanent 16F16/12P16 with no 12F12. The English variants of One and Two got the dynamic ARCs first, then the nations.
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I have a very old ONdigital box and pick up DTT from Wenvoe, and when I had a 4:3 set and had the box configured to letterbox widescreen material, it would (post widescreen-switching in Wales) always oblige and fill my 4:3 screen with 4:3 material.
Chances are your box got the OTA AFD upgrade, so whether the AFD method or dynamic ARC method is in use is transparent to you. The only boxes that didn't get it were those that were sitting in a warehouse I believe, and thus still have really old software that wasn't AFD compliant - so when configured for 4:3 with letterbox, 4:3 material (broadcast 12P16) was displayed postage stamp.
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Likewise now I have a 16:9 set, although I always choose to watch 4:3 material pillarboxed, I am quite able to stretch it to fill the screen if I choose. However, I am unable to do this with material in 4:3 format flagged as 16:9 from other channels - I have now and again experimented with zooming up letterboxed material, but don't like the results very much!
I suspect you are unable to do this when material is not flagged as 4:3 for DSat - i.e. DSat viewers also get 12P16 stuff?
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However, I'm perfectly happy to bow to your far superior knowledge of the technical details. The point I was making is that the BBC do not actively transmit 4:3 material as 16:9 unless there's been a cock-up. To the best of their ability - and allowing for any such necessary compromise in the transmission chain over which transmission staff have no control - presentation staff in both Network and Nations will always do their best to send out a picture to each platform in the format which will give the optimum resulting picture.
Well they do in England - and have always done so. They BROADCAST all 4:3 material as 12P16. However almost every DTT box on sale in the UK is aware of the AFD signalling, so presents 12P16 as 12F12 on its output.
ITV/C4 (and now, recently, Five) use the alternative mixed ratio 12F12/16F16 broadcast system.
It is easy for me to tell because my Win MCE2005 16:9 system offers me zoom options on 12F12 broadcasts, but not 12P16. (I get the zoom option on non-BBC 4:3 broadcasts, but not on BBC ones) Similarly MPEG2 recordings made directly off-air are 12P16 when BBC sourced, but 12F12 when non-BBC!
Wales may be different - though I'd be really surprised (and have read no references to this in the PC DVB-T forums - where 12P16 transmission is a major bug-bear - for the DVD burning / recording reasons I mention above!)
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As we have seen from this thread though, no matter how hard you try to deliver the correct shape of picture to the viewer, there is no legislating for what they do with it once they've received it!!
It's bad enough the BBC often screen a 4:3 programme in a 16:9 frame - so on boxes like my Sagem the ratio doesn't switch automatically from 16:9 to 4:3 meaning you get black bars all around - but lately I've noticed with BBC2 films (the films this afternoon being an example!) they put a 16:9 picture in a 4:3 frame in a 16:9 frame.
Ridiculous - ITV, C4 (especially) and five manage ratio switching properly, why can't the BBC - the corporation that's suppost to be at the forefront of the digital revolution!
The problem this afternoon is caused by the BBC showing old transfers of widescreen films which were transferred before the BBC went widescreen. It is often not the BBC's fault - the only copy of the films available for transmission is letterboxed 4:3 - with the film not available for re-transfer by the BBC.
Thus the transmission tape is 4:3 - but contains a letterbox widescreen image. Quite correctly the BBC broadcast this as if it is 4:3. (This is most common with older foreign films which have subtitles burned in) Channel Four have also done this in the past - and Film Four do on occasion. ITV don't - but mainly because they show different kinds of stuff.
Well, you can't say the BBC don't know how to crop 4:3 material!
On the widescreen sets I have I tend to watch 4:3 material in 14:9 zoom mode (so you miss the top and bottom of the picture and there are bars left and right, though not nearly as large as if you watch in 4:3).
Most 4:3 stuff broadcast now is either 14:9 anyway (in which case it's set correctly) or the missing parts of the picture don't have any useful info anyway.
On the rare occasions that this mode cuts useful info off the screen, I revert to 4:3. I too hate stretchyvision.
The 4:3 TVs are set to 16:9 letterbox (or just "wide" on the box if the set will take it and switch automatically, as this keeps full picture quality on ws transmissions as the set just fires the complete set of lines to a smaller percentage of the visible screen).
