Bruce Wheaton
Forum Replies Created
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Be very careful on your tests. Your techs won’t be able to tell the difference between ‘no delay’ and delay within 100 milliseconds or so. The brain just fixes A/V sync below that – it’s a feature!
So your testing may actually be 3 frames delay versus 4 frames delay, and it won’t look like ‘a bit more delay’, it will appear to suddenly be quite a bit off.
The main cause of latency for you is probably de-interlacing. Any time you go from an interlaced to progressive display, such as in a display device, or a DVE in a switcher, 1.5 frames is a usual minimum.
Have you tried 720p, if you’re using 1080i right now?
For testing – make a video with a clear frame indicator. I have one knocking around somewhere with a white stripe that rolls past some frame markers – 5 or so, I recall. Feed that to a monitor. Shoot the monitor with a camera and feed the camera through your signal chain right to your display. If you can frame it to see the ‘original’ monitor and the post-processing monitor or display, you end up with a video you can pause and examine.
Bruce
Regards,
Bruce Wheaton
http://www.synchromeshDDR.com -
You can use an audio DA or a video DA. Timecode is most similar to an audio signal, and apart from it being best to avoid passing it through transformers (which try to reject DC, a central part of LTC timecode), you can treat is as a line level audio signal, including balancing and unbalancing it and adjusting levels. It also happens to be close enough to an analog video signal to use a VDA.
You can also get away with splitting the signal passively, for instance with an XLR Y cable.
Here’s a specific recommendation: use a balanced audio DA with XLRs, and ideally level control on each output. Use XLR to BNC, or XLR to RCA with BNC adaptors to feed your decks (some decks may have XLR or RCA inputs). Don’t be afraid to throw a few XLR Y’s in if it makes cabling easier, especially if two decks are near each. *Do not* try to use any decks timecode output, loop-out or similar to feed other decks.
Bruce
Regards,
Bruce Wheaton
http://www.synchromeshDDR.com -
You’re right to be concerned Ken. You definitely need to supply both the Google TV and AppleTV with EDIDs that don’t have HDCP active.
But before then – run out and buy what you can and do tests! They should only be $100 or so each, way cheaper than any onsite fixes.
Bruce
Regards,
Bruce Wheaton
http://www.synchromeshDDR.com -
As a side note, 3 butted 1920 x 1080 images makes a 5.333:1 screen, not a 3:1 screen. You might refer to the setup as a 3 by 1 screen, but it’s probably important to bear the actual aspect ratio in mind.
Bruce
Regards,
Bruce Wheaton
http://www.synchromeshDDR.com -
A/V sync should be fine. There’s almost no latency on the analog run to the cameras, and the audio path through the Atem should be fine. But what mixer will take audio from HD-SDI inputs?
It would be more usual to take a finished mix from the house – try to make sure it’s an aux or similar, so your levels aren’t affected too much by the needs of mixing the PA – and insert that into the switcher just to embed the audio and record it with the video.
Request or bring isolating transformers in case of ground loops between you and the house system.
Bruce
Regards,
Bruce Wheaton
http://www.synchromeshDDR.com -
The ScreenPro should probably be downstream of the router, so it can get any source and convert it to the resolution of the projector – that’s the point. It sounds like you should have had a controller, so you could control the router and ScreenPro, and associate an input channel with each router input.
There is also a secret way to get an auto-locking input active on a ScreenPro, but it’s an advanced feature – if your guy couldn’t set the SP-II up, he wouldn’t be ready to deal with it.
Bruce
Regards,
Bruce Wheaton
http://www.synchromeshDDR.com -
It’s very do-able, Ken. A 3D capable projector for that screen size won’t be very cost-effective though (to rent or setup). You may be better off with two projectors and linear polarizing filters. That gives you the cheapest glasses, filter system, and lets you use one extra projector to back up both of the others.
Ignore any discussion of circular polarizing being better since ‘you can tilt your head’. First, you can’t see stereoscopic 3D with a tilted head, second people don’t need to rest their heads in corporate shows (mostly ; ) and third, crosstalk and light loss are worse.
You will need a screen that supports polarized projection – not sure about the dalite product.
Bruce
Regards,
Bruce Wheaton
http://www.synchromeshDDR.com -
I would try Walter’s approach for a few reasons. First is that doing 3D without exactly sync’ed outputs – as in genlocked, not just showing the same content, is a poor idea. Even if it did seem to work with two projectors, you wouldn’t be able to feed those two lines into a decent 3D projector (that makes active from dual pipe internally). It’s also a lot easier to handle side by side files and guarantee they follow the same processing path.
Bear in mind – you being able to see 3D, and the average audience member being able to see it is not the same thing, and you can have apparently working 3D that can give people screaming headaches after watching five minutes of it. A temporal difference of, let’s say up to 1/60 sec, like you would expect with two machines (no external processing) and software, could be enough to cause that.
The dual-head 2 Go will produce 2 time aligned outputs that are definitely the same frame. Even better is two outputs right from a GPU.
Bruce
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Do all your projectors really need to be that far off axis? Horizontally as well as vertically? That’s a pretty crazy projection setup.
Anyway, I would look at using a single HD source of 1920 x 1080 and using in-projector blending and warping – Christie Twist springs to mind.
Otherwise, you’ll have to discuss what input sources you need to handle a bit more. There isn’t really a single scaling/processing solution that will do everything you want, but if your sources permit, there are playback solutions that might fit.
Regards,
Bruce Wheaton
Regards,
Bruce Wheaton
http://www.synchromeshDDR.com -
We stay native as much as we can – on the DDR, that’s a wide range of codecs and bitrates. For the lower spec Turbine, we’re going to do an automatic reconversion to the best format, probably a tweaked H.264 movie. But the main thing is that we’re going for a one-step process, the reading from disk, transcoding and distribution will happen at the same time (even to all units) as opposed to sequentially.
The idea of Tracks is that you play a clip on ‘Track A’, for instance, instead of on a deck/s, and then any deck that has Track A active will play the file, each with it’s own scaling and conversions. That can include playing the clip onto ‘Virtual Screens’ which might span multiple outputs or be just chunks of another output. It means that you can do some mild configuration up front, then almost no programming.
BTW, if anyone is in the Bay Area, and would like to attend the demo – Oct 22nd and 23rd, please drop me a note. We’re talking to producers and media creators at this particular demo.
Bruce
Regards,
Bruce Wheaton
http://www.synchromeshDDR.com