How do I get rid of the horrible screen that flashes up when I switch
inputs to my projector?
my projector puts up a big
blue(black/yellow/whatever) screen every time my switcher switches - can I stop
this happening as it looks very amateurish?
You are experiencing the BSOS (Blue screen of
sync)!
Maybe. Depends on projector, switch and what you are switching.
The basic problem is that the projector is loosing sync with the incoming video. This is probably happening because you are using a mechanical switcher that is monentarily disconnecting the signal while it switches over from one input to the other - this is very common with consumer AV switchboxes. Another reason may be that you are switching video sources that are not themselves synchronised, that is they do not start each video frame at the same time. Unless the sources are sync'd or 'genlocked' or have both been put through a timebase corrector (TBC) this would be the case. The projector is expecting a sync pulse at a certain time to start displaying each frame of video. If it starts missing a few, it decides there may be no signal present and displays a helpful message to this effect. Unfortunately if it displays this message to the 500 people in your audience just as your speaker is getting to a serious point, then its not that helpful.
There is really only one way to ensure that this never happens, and that is to never stop sending video sync pulses to the projector. This means that something has to keep sending them even when you are switching.
This can be either be a pro switcher that uses electronic switching rather than mechanical switching, or a video mixer that outputs stable sync'd video regardless of what is happening on the inputs.
There is another way to avoid this, which is to see whether your projector can be set up to NOT display this message when it loses sync - some projectors can turn this option off (or just display a blank black screen instead) which is much preferrable.
One other option, if your switcher does switch OK without dropping sync, but the problem is that you are needing to go to a blank screen and are switching to an unused input to achieve this, then you need to have SOMETHING on that input driving sync pulses to keep everything happy. It could be a computer scan converter or TV out displaying a black screen, an old camera with its iris closed, a VCR playing a blacked tape etc. etc.
Maybe. Depends on projector, switch and what you are switching.
The basic problem is that the projector is loosing sync with the incoming video. This is probably happening because you are using a mechanical switcher that is monentarily disconnecting the signal while it switches over from one input to the other - this is very common with consumer AV switchboxes. Another reason may be that you are switching video sources that are not themselves synchronised, that is they do not start each video frame at the same time. Unless the sources are sync'd or 'genlocked' or have both been put through a timebase corrector (TBC) this would be the case. The projector is expecting a sync pulse at a certain time to start displaying each frame of video. If it starts missing a few, it decides there may be no signal present and displays a helpful message to this effect. Unfortunately if it displays this message to the 500 people in your audience just as your speaker is getting to a serious point, then its not that helpful.
There is really only one way to ensure that this never happens, and that is to never stop sending video sync pulses to the projector. This means that something has to keep sending them even when you are switching.
This can be either be a pro switcher that uses electronic switching rather than mechanical switching, or a video mixer that outputs stable sync'd video regardless of what is happening on the inputs.
There is another way to avoid this, which is to see whether your projector can be set up to NOT display this message when it loses sync - some projectors can turn this option off (or just display a blank black screen instead) which is much preferrable.
One other option, if your switcher does switch OK without dropping sync, but the problem is that you are needing to go to a blank screen and are switching to an unused input to achieve this, then you need to have SOMETHING on that input driving sync pulses to keep everything happy. It could be a computer scan converter or TV out displaying a black screen, an old camera with its iris closed, a VCR playing a blacked tape etc. etc.
Posted: Sat - September 6, 2003 at 09:15 AM |
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This site contains my personal views, ideas, tips, tricks and rants about doing live video, IMAG or graphics at live events on a very low budget. They are published as I get time, in a style closely approximating a weblog. Dave C.
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My name is Dave Chalmers and I live in Edinburgh in Scotland, UK. My background is in Electronics, but for 10 years I have been helping to put on live video at events in central Scotland in my spare time. Through the course of these events, nearly all on very constrained budgets, I have learned a few things about what works and what doesn't. While I would not claim to be able to give you all the answers, I can at least help you avoid some of the mistakes.
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Published On: Jul 06, 2006 11:37 PM
Total entries in this category: 16
Published On: Jul 06, 2006 11:37 PM