NG
Yep - analogue is still VERY useful for off-air confidence... (Most galleries monitor off-air on analogue - as digital with the umpteen seconds of MPEG2 coding/decoding delay is enough to drive you bonkers...)
I assume they they chose that as a source so to avoid any extra delay, unless they were lucky enough to be able to get across the line from 'Lottery HQ'
Yep - I'd be VERY surprised if they even considered attempting to get across the incoming line and routing it to their studio. That would ride a coach and horses through the legal "fair dealing" that they probably used to show the result at all. For that you have to use off-air I think...
Still, I'm surprised how exactly it was on that video, especially considering the route that the BBC1 via More 4 image would have taken including 2trips through Red Bee
Assuming analogue BBC One off-air has zero delay (in reality it may have a couple of frames relative to the originating studio - but not much) and is the reference, and assuming roughly similar encoding GOPs are used on both BBC One and More 4 MPEG2 encoders, then the only difference between a digital BBC feed and a digital C4 feed will be the extra delay that is involved with getting the BBC One analogue feed to a screen in the Derren Brown studio (flat panels usually introduce a frame or three), the delay via the camera and mixer in that studio (often just a few lines?), and the delay via the circuit (again not that much), and a frame synchronise or two into the playout area at Red Bee. Could easily be around 5 frames?
noggin
Founding member
Ahhh, I'd forgotten about analogue (as sad as that sounds), that would make sense.
Yep - analogue is still VERY useful for off-air confidence... (Most galleries monitor off-air on analogue - as digital with the umpteen seconds of MPEG2 coding/decoding delay is enough to drive you bonkers...)
Quote:
I assume they they chose that as a source so to avoid any extra delay, unless they were lucky enough to be able to get across the line from 'Lottery HQ'
Yep - I'd be VERY surprised if they even considered attempting to get across the incoming line and routing it to their studio. That would ride a coach and horses through the legal "fair dealing" that they probably used to show the result at all. For that you have to use off-air I think...
Quote:
Still, I'm surprised how exactly it was on that video, especially considering the route that the BBC1 via More 4 image would have taken including 2trips through Red Bee
Assuming analogue BBC One off-air has zero delay (in reality it may have a couple of frames relative to the originating studio - but not much) and is the reference, and assuming roughly similar encoding GOPs are used on both BBC One and More 4 MPEG2 encoders, then the only difference between a digital BBC feed and a digital C4 feed will be the extra delay that is involved with getting the BBC One analogue feed to a screen in the Derren Brown studio (flat panels usually introduce a frame or three), the delay via the camera and mixer in that studio (often just a few lines?), and the delay via the circuit (again not that much), and a frame synchronise or two into the playout area at Red Bee. Could easily be around 5 frames?