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Topic: Digital show starts without one color...
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Stephen Furley
Film God
![](http://www.film-tech.com/ubbmembers/1277b.jpg)
Posts: 3059
From: Coulsdon, Croydon, England
Registered: May 2002
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posted 08-30-2008 07:36 AM
quote: Pete Naples If this was a D Cinema show, that statement is not true. The signal to a D Cinema projector from the server is carried by dual link SDI.
It would be possible if the trailers were run form some sort of alternative content system, via a DVI link, though it's not likely since all of the signals are carried on one connector. If it was a broken wire in a cable it seems unlikely that it would have been diagnosed and fixed that quickly. It would be more likely with analogue signals on 3, 4 or 5 separate BNC cables if one of them was incorrectly connected.
A re-boot would be likely to take more than a few seconds, and I can't think of any format/system mis-match which would simply drop the blue. There hadn't been a technician working on the system before the first show that had turned off the blue channel for some reason and forgotten to turn it back on, had there? Even that seems unlikely, since he/she would be likely to check the picture when they finished, and unless they were still there, and realised what had happened it probably wouldn't have been fixed that quickly.
How are the bits shared between the two HDSDI links in a digital cinema system? does each cable carry half the bits for each pixel, or half the pixels for each frame, or do the two cables carry alternate frames, or what? I've never tried disconnecting one cable to see what would happen, but I suspect that you'd lose the entire picture. Does one link carry the clock for both, in the same way that the first AES pair for the audio carries the clock which is used by all four pairs?
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Stephen Furley
Film God
![](http://www.film-tech.com/ubbmembers/1277b.jpg)
Posts: 3059
From: Coulsdon, Croydon, England
Registered: May 2002
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posted 08-31-2008 04:33 AM
quote: Mike Renlund Cable 1 (Left Eye) Red - 4 bits Green - 2 bits Blue - 2 bits
Cable 1 (Right Eye) Red - 4 bits Green - 2 bits Blue - 2 bits
Did you mean 'Cable 2 (Right Eye)', otherwise cable 2 doesn't seem to be doing anything?
Why 4 bits for R and only 2 for G and B? The RGB colour space normally uses the same bandwidth for each channel, unlike the various colour difference systems.
What does this 4 and 2 bits, mean anyway? This obviously isn't enough to transmit the full range of colours, is this 4 bit, 2 bit, 2 bit pattern repeated several times to build up te full pattern of bits for each pixel? If so, then why; why not just transmit all of the red bits, then all of the green, then all of the blue? What is the total bit rate of a HD-SDI interface anyway?
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