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Same with others? Boscam Rx-LCD 5802 Aspect Ratio Issue

Discussion in 'Phantom 2 Discussion' started by d4ddyo, Apr 14, 2014.

  1. d4ddyo

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    I am wondering: Does this happen with other LCDs or Do they auto switch resolution/aspect ratios based on input like a monitor or TV?

    Somewhere in this forum people were asking about the Boscam Rx-LCD 5802 and there either be black bars above or to the side. I have been playing around with everything on and switched resolutions on the gopro and come to this conclusion.

    The resolution of the LCD is only a mere 800 x 480. which is a 16:9 display.
    According to Boscam specs. the aspect ratio can be changed to 4:3.
    So for some reason in my case.... my boscam is displaying 4:3

    If i select a resolution of 1080p 16:9 and my boscam is 4:3... then black bars show up like letterbox! Which is the case!
    If i select a resolution of 1440p which is 4:3... then it fills up the screen... why? because the boscam is displaying 4:3


    Soooo i'm sure if it were displaying 16:9... then displaying 1080p is filling up the entire screen.

    I went nuts trying to figure this out because all of a sudden i have these letterbox bars on top and bottom. it started when I have been using 1080p

    I was using 1440p in the past because of watching MicBergsma youtube video on resolution. He recommends using 1440 and post editing to 1080p to remove landing gears and/or props that show up on the video.

    when i bounced that idea and wanted to use 60 frames/s then i had to come down to 1080p.

    so here's the next annoying question. How to switch the aspect ratio on the boscam because apparently it's switchable.
    Read specifications here: http://www.helipal.com/boscam-7-monitor ... evier.html

    Specifications :
    - Dimension : 180 x 120 x 23mm
    - Weight : 420g
    - Signal Input : Built-in 5.8Ghz AV Output and 1Ch AV Input
    - Diagonal. size : 7 inch
    - Scale : 16 : 9 (Adjustable to 4:3)
    - Angle of view : 140(V) x 120(H)
    - Brightness : 450cd/m2
    - Contrast : 500 : 1
    - Screen Resolution : 800 x 480
    - Power consumption : < 8W
    - Operating temp. : -20℃-+65℃

    Under Scale it reads Scale: 16:9 (adjustable to 4:3)

    What gives?
     
  2. d4ddyo

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    Re: Same with others? Boscam Rx-LCD 5802 Aspect Ratio Issu

    Anybody have these issues with others like Black Pearl?
     
  3. Joel_t

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    Re: Same with others? Boscam Rx-LCD 5802 Aspect Ratio Issu

    Looking at getting this monitor too so just wondering if you've had any luck with it? I can try to talk you through it to see if things work but sounds like you already know what you're talking about.

    Firstly you'll need to make sure that it is actually the monitor causing the problem. Say the GoPro is set to 1920 x 1080 at 25fps. The signal coming out of the GoPro is what? 1080p still? It may do a downconversion on the go to make it smaller. I doubt shooting in 4K means the GoPro outputting in 4k (could totally be wrong here though)

    Then the signal hits your VTX. Now these can't do 1080p so something is converting it to either PAL or NTSC. Neither of which are native 16:9. PAL is 720 x 576 and NTSC is 720 x 480 (I think, I never use this being in Australia).

    To get a 16:9 image from either PAL or NTSC the monitor uses a pixel aspect ratio to convert it to widescreen. This mean each square pixel gets slightly stretched to fit a 16:9 ratio unlike HD (1920 x 1080) which is a native 16:9 ratio.

    So if you put your monitor into 4:3 mode you should see a picture that is pillarboxed (black lines down the sides) but still touches the top and bottom of the screen. The image should look squished / skinny. If you can get this image to look right then changing your monitor to 16:9 should stretch the image to fill screen and image should look fine.

    If in 4:3 the image is both pillarboxed and letterboxed (black bars around all sides of the image) then something earlier in the process is set wrong.

    Dunno if this is any help to you but maybe will help you work out the solution
     
  4. GhostMaster

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    Re: Same with others? Boscam Rx-LCD 5802 Aspect Ratio Issu

    Thats strange, i get a clear image from mine and its full screen non distortion.

    Did you change anything in the settings?
     
  5. Yeadonites

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    Re: Same with others? Boscam Rx-LCD 5802 Aspect Ratio Issu

    I'm assuming we are taking about using this kind of setup:

    GoPro Hero3
    DJI Gimbal 2D/3D
    DJI IOSD
    Analogue TX/RX
    A widescreen display

    Firstly, all composite analogue video is 4:3. Widescreen technically does not exist in a composite SD form.
    To fudge an analogue widescreen signal we use anamorphic widescreen, that is how a DVD gives you a widescreen picture (unless it's a very old letterboxed version) when the Mpeg2 video encoded on a DVD is in fact 4:3 (720x576 in PAL for example with a non-square pixel ratio)

    So any downconversion is happening in the GoPro from whatever HD format it's set in, to a composite SD signal.
    The analogue output on the back on the GoPro into the gimbal is always a 4:3 signal.
    The GoPro is letterboxing the 16:9 formats into the 4:3 signal when it should be anamorphicly squeezing it.
    The 4:3 formats are passed straight through.

    That then gets passed through the FPV TX and RX chain, until it arrives at the screen.
    And if you view it in 16:9 it will stretch it out to fill the width of the screen, but most of the GoPro format options will have a letterbox and all need to be viewed in 4:3 to show the image in the proper aspect.

    The chip on a Hero3 is 4:3 (4000x3000 - 12MP) and a format such as 1440p is also 4:3.
    So that's why the GoPro's output fills the screen in 1440p, though it's actually the wrong shape on a 16:9 screen, technically you need to set the screen to 4:3.

    It seems like the GoPro doesn't have the processing power to manipulate all of it's recoding formats into anamorphic signals when required. I've done a little testing and the only decent formats that give a full screen (full raster) image are 1440p and 960p.
    Basically the GoPro is letterboxing everything else, so the only way to view in a proper aspect ratio is to set the monitor to 4:3 no matter what mode the GoPro is set on.

    4k is of course very low frame rate.
    2.7k is also noticeable strobing, but hopefully not enough to affect FPV flying as long as you aren't performing extreme manoeuvres.

    I've seen that some groups have hacked the GoPro to add other options including some anamorphic manipulation, but I'm not sure if they are reliable working solutions.
     
  6. d4ddyo

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    Re: Same with others? Boscam Rx-LCD 5802 Aspect Ratio Issu


    Thanks! so it's operating as intended. makes sense. I didn't take into account the Gopro feed.
     
  7. Yeadonites

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    Re: Same with others? Boscam Rx-LCD 5802 Aspect Ratio Issu

    Yes, it is indeed working 'correctly'. And you need to set your monitor to 4:3 to view in the correct aspect ratio.
    CRAP INNIT?

    I've contacted GoPro, but I'm not expecting a fix.
     
  8. d4ddyo

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    Re: Same with others? Boscam Rx-LCD 5802 Aspect Ratio Issu

    Yeah! I was going completely bonkers! Don't tell me... the little display back display is 4:3?