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Author
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Topic: DSS200 / NC2500S - Picture loss when skipping in playlist
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Leo Enticknap
Film God
Posts: 7474
From: Loma Linda, CA
Registered: Jul 2000
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posted 06-13-2015 06:58 PM
System as follows:
Dolby DSS200 and cat862, with software version 4.8.4.10
NEC NC2500S, with software version 1.02 (BIOS) ; 2.11 (firmware and data) ; 15.1 (TI)
The two connected by dual-link SDI (obviously)
Occasionally, when I press the skip forward or skip back button in a playlist, the picture disappears. This happened once during a festival last week (thankfully during testing rather than the actual show), and has happened again just now. I had a 10-second DCP of a backdrop slide paused in the middle while someone was talking, and then pressed skip forward to start the actual show, which was the next DCP in the playlist. After pressing skip, the sound started as it should have done, but no picture.
Rebooting either the server or the projector in isolation doesn't solve the problem - I needed to do a full (as in, actually cutting the power supply for 20 seconds after shutdown) power-down reboot of both.
This leads me to suspect that the problem is with the interaction between the cat862 media block and the projector, because :
A - the audio plays, that comes out of the media block, and so the media block can't have frozen totally;
B - the picture doesn't come back if I simply soft-reboot the server (pressing ctrl+F1, then login, then "reboot"). My understanding is that doing that doesn't reboot the media block at all (because the power supply to it from the server's motherboard is maintained throughout the rebooting process), just the server sending data to it;
C - the picture doesn't come back if I reboot the projector without doing anything to the server, so the problem can't just be in the projector.
Other possibly relevant info:
A - none of the DCPs in the playlist that glitched either in the last incident or now were encrypted.
B - the last software updates were done in March and the problem only happened for the first time last week, and so I don't think it's a hard-coded bug in the software. If it is, the other circumstances needed for the bug to work only fell into place last week.
Anyone had this happen before, and if so any suggestions? I'm thinking that a clean reinstall of the cat862 firmware might be worth doing. Many thanks in advance.
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Leo Enticknap
Film God
Posts: 7474
From: Loma Linda, CA
Registered: Jul 2000
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posted 06-14-2015 10:48 AM
I was wondering about TLS too, because that system was previously on DS and was only changed to TLS in March. The scenario I was wondering about was some sort of TLS security handshake that takes place at the start of the playout for each individual DCP (hence the 1-2 second pause that happens when progressing from one DCP to the next in a playlist, even when things are working normally). Thanks to a bug either in the 862, the projector or both, when the skip button is pressed, that handshake doesn't complete successfully as far as the projector is concerned (so no picture), but the 862 believes that it has, therefore audio playout continues as normal.
But that wouldn't in itself explain why our DSS200/cat862/NC2500S combo worked happily and reliably for three months after the last round of software updates, and only started to do this last week. It also wouldn't explain completely why this only happens on some manual skips but not others. It seems that a specific set of circumstances need to be in place for this bug to act, and I haven't figured out what they all are yet.
Annoyingly, when our system gnarls up, it does so to a black screen, not a white one, so the audience was probably thinking that I'd forgotten to do something in yesterday's show. A white screen would at least say "technical problem" to everyone, loud and clear.
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