IT
It's been used for a number of things over the years. I think UK Today used to use it (along with a small desk) in the original 1999 set. The BBC ONE summaries used to come from in front of it for a time (when they stood up with a News Centre background). I also seem to recall it being mentioned that BBC World's programmes 'This Week' and 'Reporters' used it as well, though I don't know if that still happens.
itsrobert
Founding member
dosxuk posted:
Didn't they use to use it for pre-records for the main news?
It's been used for a number of things over the years. I think UK Today used to use it (along with a small desk) in the original 1999 set. The BBC ONE summaries used to come from in front of it for a time (when they stood up with a News Centre background). I also seem to recall it being mentioned that BBC World's programmes 'This Week' and 'Reporters' used it as well, though I don't know if that still happens.
NS
It's been used for a number of things over the years. I think UK Today used to use it (along with a small desk) in the original 1999 set. The BBC ONE summaries used to come from in front of it for a time (when they stood up with a News Centre background). I also seem to recall it being mentioned that BBC World's programmes 'This Week' and 'Reporters' used it as well, though I don't know if that still happens.
The CSO in N6 is still used quite a lot. Often there are graphics that don't work in the big screens so they are done with the CSO, and as has been mentioned Reporters etc use it, plus now the 8pm summary. It is just a green screen. There is another CSO area near N6 which is used for the interactive news loops, some pre-recorded graphics for progs like BBC 4 News and live with N10 for 60seconds. That is not a green screen but a blue one which tends to key slightly better but limits the presenters in what they can wear.
NickyS
Founding member
itsrobert posted:
dosxuk posted:
Didn't they use to use it for pre-records for the main news?
It's been used for a number of things over the years. I think UK Today used to use it (along with a small desk) in the original 1999 set. The BBC ONE summaries used to come from in front of it for a time (when they stood up with a News Centre background). I also seem to recall it being mentioned that BBC World's programmes 'This Week' and 'Reporters' used it as well, though I don't know if that still happens.
The CSO in N6 is still used quite a lot. Often there are graphics that don't work in the big screens so they are done with the CSO, and as has been mentioned Reporters etc use it, plus now the 8pm summary. It is just a green screen. There is another CSO area near N6 which is used for the interactive news loops, some pre-recorded graphics for progs like BBC 4 News and live with N10 for 60seconds. That is not a green screen but a blue one which tends to key slightly better but limits the presenters in what they can wear.
DE
I don't know why the BBC refer to Chroma Key as CSO, but I would imagine it stems from the days when the BBC designed and built its own equipment rather than buying off the shelf stuff. These days BBC studios use vision mixers you'd find anywhere else, but until the late 80s (maybe into the 90s?), the BBC had its own design for a vision mixer. Each source had not only a cut button but a sound-desk style fader above it.
SP
The faders were even the right way up
deejay posted:
Each source had not only a cut button but a sound-desk style fader above it.
The faders were even the right way up
NG
noggin
Founding member
CSO stems from the BBC designed Colour Separation Overlay unit that could be added to BBC designed mixers. (Not all BBC mixers were "fader a channel" devices though) The American mixers called it ChromaKey - as it derived a Key signal from the Chroma signals.
The BBC also had devices called Inlay and Overlay dating back to the days of B&W - which would these days be described as Split Key and Luminance Key (or is is the other way round?). Split key uses two signals to superimpose over a 3rd (one makes the cut out, the other fills it), Luminance key superimposes one signal over another based on the content of the signal being overlaid.
Overlay was developed into Colour Separation Overlay when colour cameras were introduced - and it became possible to derive keys from colour signals not just luminance. (Until then most special effects using overlay/inlay had required you to key off black or white areas of the picture - if you weren't using a separate caption camera with a cutout mask to do the keying)
Should also stress that CSO isn't the same as "Keying" - Keying is a much wider technique - there are split keys, luminance keys, linear keys, clean keys and these days depth keys as well as chroma keys.
In the US keying and matte-ing are both used to describe the keying technique - with the matte term coming from the film industry. Those coming from a PC world will also use "Alpha channel" rather than key as a term as well...
Chroma Key isn't a universal term - Ultimatte make some of the best chroma key devices (or software algorithms) and in some areas Ultimatte is to chroma key what aston is to lower thirds in the UK.
Most BBC areas still use CSO as the term - it has just stuck...
Also - many people aren't aware that CSO dates back to the days of black and white TV - when the BBC - and some US broadcasters - had experimental cameras with two camera tubes. One captured the normal black and white signal, but one was sensitive only to blue (I think) light - and could be used to generate a key signal. Although you were only producing black and white pictures, you could use colour in the set to "cut out" people or objects. Wasn't widely used as colour cameras became available.
The BBC also had devices called Inlay and Overlay dating back to the days of B&W - which would these days be described as Split Key and Luminance Key (or is is the other way round?). Split key uses two signals to superimpose over a 3rd (one makes the cut out, the other fills it), Luminance key superimposes one signal over another based on the content of the signal being overlaid.
Overlay was developed into Colour Separation Overlay when colour cameras were introduced - and it became possible to derive keys from colour signals not just luminance. (Until then most special effects using overlay/inlay had required you to key off black or white areas of the picture - if you weren't using a separate caption camera with a cutout mask to do the keying)
Should also stress that CSO isn't the same as "Keying" - Keying is a much wider technique - there are split keys, luminance keys, linear keys, clean keys and these days depth keys as well as chroma keys.
In the US keying and matte-ing are both used to describe the keying technique - with the matte term coming from the film industry. Those coming from a PC world will also use "Alpha channel" rather than key as a term as well...
Chroma Key isn't a universal term - Ultimatte make some of the best chroma key devices (or software algorithms) and in some areas Ultimatte is to chroma key what aston is to lower thirds in the UK.
Most BBC areas still use CSO as the term - it has just stuck...
Also - many people aren't aware that CSO dates back to the days of black and white TV - when the BBC - and some US broadcasters - had experimental cameras with two camera tubes. One captured the normal black and white signal, but one was sensitive only to blue (I think) light - and could be used to generate a key signal. Although you were only producing black and white pictures, you could use colour in the set to "cut out" people or objects. Wasn't widely used as colour cameras became available.
DE
I didn't know about that - very interesting! I'm sure I've read somewhere (probably on the excellent History of London's TV Studios site) that a favourite, if rather 'one-take only' method of keying sometimes employed in the BBC was to place a thin layer of rice over a caption placed under a rostrum camera, key that to air (i.e. full fill) then blow the rice away revealing the caption! Such ingenuity! And we moan when an end credit squeeze doesn't work correctly...!
noggin posted:
Also - many people aren't aware that CSO dates back to the days of black and white TV - when the BBC - and some US broadcasters - had experimental cameras with two camera tubes. One captured the normal black and white signal, but one was sensitive only to blue (I think) light - and could be used to generate a key signal. Although you were only producing black and white pictures, you could use colour in the set to "cut out" people or objects. Wasn't widely used as colour cameras became available.
I didn't know about that - very interesting! I'm sure I've read somewhere (probably on the excellent History of London's TV Studios site) that a favourite, if rather 'one-take only' method of keying sometimes employed in the BBC was to place a thin layer of rice over a caption placed under a rostrum camera, key that to air (i.e. full fill) then blow the rice away revealing the caption! Such ingenuity! And we moan when an end credit squeeze doesn't work correctly...!
NG
Yep - rice and fine powder (dust) were used AIUI - and other techniques.
The floor manager on News programmes used to have to pull bits of black cardboard out to reveal text/numbers for graphics as well...
I didn't know about that - very interesting! I'm sure I've read somewhere (probably on the excellent History of London's TV Studios site) that a favourite, if rather 'one-take only' method of keying sometimes employed in the BBC was to place a thin layer of rice over a caption placed under a rostrum camera, key that to air (i.e. full fill) then blow the rice away revealing the caption! Such ingenuity! And we moan when an end credit squeeze doesn't work correctly...!
noggin
Founding member
deejay posted:
noggin posted:
Also - many people aren't aware that CSO dates back to the days of black and white TV - when the BBC - and some US broadcasters - had experimental cameras with two camera tubes. One captured the normal black and white signal, but one was sensitive only to blue (I think) light - and could be used to generate a key signal. Although you were only producing black and white pictures, you could use colour in the set to "cut out" people or objects. Wasn't widely used as colour cameras became available.
Yep - rice and fine powder (dust) were used AIUI - and other techniques.
The floor manager on News programmes used to have to pull bits of black cardboard out to reveal text/numbers for graphics as well...
I didn't know about that - very interesting! I'm sure I've read somewhere (probably on the excellent History of London's TV Studios site) that a favourite, if rather 'one-take only' method of keying sometimes employed in the BBC was to place a thin layer of rice over a caption placed under a rostrum camera, key that to air (i.e. full fill) then blow the rice away revealing the caption! Such ingenuity! And we moan when an end credit squeeze doesn't work correctly...!