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screen resolution vs video resolution using projectors

Nils Marklund

December 05, 2019 08:10

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In video formats there is just so much going on that I sometimes are not sure that my videos are displaying correctly. 

In a simple project, just to display a hd-video 1920x1080 on a projector with native 1920x1200. Is it best to choose 1920x1200 as screensize in new presentation options in BA and chose the same format in projector settings when displaying? Or do I chose 1920x1080 as screensize for the presentation options in BA and setup the projector as 1920x1080.

How do you setup, and what is working for you?

All the best

/nils

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3 comments

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  Allen H. Porter December 05, 2019 12:34

  We do not do much with projectors but in general we aim to match everything.  So if content is 1920X1080 (60p), that is the Presentation resolution and the display must support that as well.  Allowing the various devices to "scale" the video always seems to cause some issue.

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  Nils Marklund December 06, 2019 12:44

  I see. In my case there will always be some scaling/trimming because the native resolution of the projector is different from the video resolution. So there will be some "lost" or unused pixels one way or the other. I deal with a lot of video in art/photo exhibitions and it is important to get the aspect ratios right and also fill as much of the display/projection as possible without cropping and keeping letterbox to a minimum.

  I'm guessing keeping kontent/video resolution same as presentation resolution in BA and let the projector trim/scale/"letterbox" will keep the scaling to a minimum. At least this is the way I normally do it. Was just curious if I got it backwards or if there were a better way to do it, like letting BA do the work. To complicate things there is also the view mode feature in BA.

  all the best

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  Brandon December 06, 2019 23:17

  Which device should be allowed to scale and do framerate conversion really depends on the devices.

  Some devices scale well, others scale poorly, some do better in specific situations - same with framerate conversion.

  Though in the case of synchronized playback across multiple players, you want to minimize any processing downstream from the player, as it can throw the sync off.  Even though the players are outputting synchronized frames and synchronized redraws, if the displays are making their own adjustments, it can result in inconsistent delays across the displays.

  There are also other factors like zoom vs scaling - sometimes it's better to use a smaller part of the display area without scaling and use optical zoom with shuttering than to scale to the full resolution.  For LCD projectors you have to screen door effect to consider with zoom as well, but this works great for CRT projectors as it's more of an analog process that fills in the gaps.

  In the specific case of 1920x1200 and 1280x800 16:10 aspect ratio projectors, you have the option of using the native resolution output and having the extra lines for header/footer message display or you can use it for debugging information if it's an interactive project.

  However if you are synchronizing multiple projectors for stacked/blended/adjacent display, be aware that neither 1920x1200 nor 1280x800 output modes are whole-number clocks, meaning they are 59.something Hz rather than 60.00 Hz and therefore there will be periodic partial-frame draws which can cause visual discrepancy if the displays do not have synchronize redraw (V-sync).

  BrightSign firmware 7.0.60 introduced a Genlock function for synchronized presentations that attempts to align the V-sync across players to avoid visual discrepancies due to partial-frame cadence differences.  It has been progressively adjusted since, so BrightSign OS 8.0.77 and newer gives the best chance of success there, but displays/projectors can still opt to ignore the redraw timing which will cause visual continuity glitches.

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