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  1. Member
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    Hi guys,

    I need some help to understand the video signal from a BNC video output port. There is a X-Ray machine, model GE 9900 Elite, which has several video output ports, such has BNCs and DVI. A X-Ray machine usually has 2 monitors. I need to capture the video signal on the left monitor. I have attached an image regarding to the ports from the X-Ray machine with labelling. According to the manual, Number 1 and number 2 BNC ports are the video signals display on the left monitor screens, where 1st one is hi-resolution, and 2nd is lower resolution. The 3rd BNC port is for right monitor, and the DVI is also for right monitor. Note: the image below shows covers protecting the BNC and DVI ports.

    Image
    [Attachment 50900 - Click to enlarge]


    From my understanding, this BNC port is outputing analog video signal, and definitely not SDI signal. I need a converter to convert the video signal from the BNC port to DVI interface to display video on external monitor. I'm wondering the video signal from the BNC port is what kind of signal ? I am currently using scanmaxx dv2165mp analog to dvi video converter. It has RGBHV bnc input, where i can only connect the 1st BNC port from the machine to "G" port of converter, the converter manage to convert to DVI, but slightly distorted (circle become ellipse, some portion cropped off) output. Other BNC ports from the converter will not work. I have tried many of the same model X-Ray machine or different model X-Ray machine with BNC output port, some doesn't distort, but a few do have distorted signals after conversion. The scanmaxx 2165mp image is attached below

    Image
    [Attachment 50901 - Click to enlarge]


    Therefore, i'm looking for other alternative to the scanmaxx converter that i have got. I also used 5 BNCs to VGA converter cable. Also, only connecting to the Green color BNC cable works to convert the video, other color will not work. Do anybody know what's the relationship between RGBHV and composite video ? Why only connecting the 'Green' port of the converter will works ?

    Image
    [Attachment 50902 - Click to enlarge]


    At this point, I'm assuming the BNC output from X-Ray is a composite video. Then, I got online for another composite video to VGA converter. This is not the cable i mention above, it only have 1 BNC port for composite video, rather than the 5 ports of RGBHV like scanmaxx 2165mp and the 5 BNCs to VGA cable. I try connecting the X-ray machine BNC port to this newly bought converter, nothing is converted. This converter has been tested working to convert composite video to VGA signal with CCTV system port though, I am sure this converter is not defect.

    Image
    [Attachment 50903 - Click to enlarge]


    Therefore, I am now kinda confused with the signal from the X-Ray machine, is it a composite video ? Why is it only connecting to "G" of RGBHV converter will works. What's the relationship of 'G' port with composite signal ? What kind of converter i need to convert the signal from X-Ray machine to external monitor ?

    Sorry for such long post, I search all over the internet, i still cannot get my answer. Appreciate all the helps from u guys.
    Last edited by diontan; 18th Nov 2019 at 01:31.
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  2. Dinosaur Supervisor KarMa's Avatar
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    A single BNC usually just outputs a composite video signal. The same signal that is normally carried on a RCA Composite Yellow Cable (along with the Red/White audio cables). There are $5 BNC to RCA adapters on Amazon. This would allow you to look at the video on just about any TV.

    I'm a little confused about everything here in your post but with RGBHV (VGA), that's a RGB signal and not directly compatible with YPbPr/YUV (Composite). The only thing I guess that is compatible between the signals is the Green, which Composite treats as the Luma (Black and White) and does not require an additional signal.
    Last edited by KarMa; 18th Nov 2019 at 03:00.
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    My aim here is to add another monitor for the X-Ray, which provides only a single BNC port. My monitor only accept VGA/DVI. Therefore, i need a converter to convert the signal from BNC to DVI/VGA. I currently have 3 types of converter, scanmaxx dv2165mp (analog to DVI) as shown in 2nd image in my post -> which has 5 BNC input ports (R,G,B,H,V). Only connecting to the G (Green) port, the converter is able to output the signal to DVI. The second converter is a 5 BNC (R,G,B,H,V) to VGA cable (as shown in 3rd image). It is also the same as the scanmaxx dv2165mp, where only connecting to the G (green) bnc connector, there will be output to my external monitor. The reason i don't really want to use scanmaxx dv2165mp and the RGBHV to VGA cable is that i faced some distortion issue. Thus, I am looking for alternative.

    I have the same thought here, usually 1 BNC output from any device should be composite signal (analog) or SDI (digital). Therefore, I go on to buy a third converter, which is composite video to VGA converter (as shown in last image). This converter only accept 1 BNC input. However, this converter doesn't work on the X-Ray machine. No signal to my monitor at all.

    Here comes back to the question, is the signal from X-Ray is a composite video? If yes, why the 3rd converter doesn't work ? And why is it connecting to "G" of R,G,B,H,V will work? But maybe like what u said, "The only thing I guess that is compatible between the signals is the Green, which Composite treats as the Luma (Black and White) and does not require an additional signal.". Maybe that explain why connecting to green port will work. But I am unsure too. If it's composite video, the 3rd converter should work. Is there anyone has knowledge of this ? Please help me out. Is there any suggestion of converter?
    Last edited by diontan; 18th Nov 2019 at 03:37.
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  4. Therefore, I am now kinda confused with the signal from the X-Ray machine, is it a composite video ? Why is it only connecting to "G" of RGBHV converter will works. What's the relationship of 'G' port with composite signal ? What kind of converter i need to convert the signal from X-Ray machine to external monitor ?
    The port is labeled G/Video and the website specs mention supporting 1 to 5 signal input and analog grayscale so it's possible the box can accept (black and white) composite as well as various RGB formats. Are there some settings in the menu for different input types? The converter has to know that the sync signal is on the same input as the video, don't know if it can determine that by itself. It is possible that it outputs some sort of non-standard higher res black and white signal analog that signal converters may struggle with though this device does seem specialized for this sort of source.
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  5. It's very common for VGA to have HV (horizontal and vertical sync) on G as well as separate HV pins. Some VGA monitors only have three inputs (RGB) so sync has to be carried on one of them, Green. The composite to VGA converter probably doesn't work because your source isn't NTSC or PAL composite video (interlaced, low res). Try connecting directly to a VGA monitor (3 pin or 5 pin) that reports scan rates and resolution. I suspect you'll find it's putting out a standard VGA signal (higher resolution and scan rates than NTSC/PAL).
    Last edited by jagabo; 18th Nov 2019 at 07:33.
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  6. Why can't you just use the DVI output from the x-ray machine directly?
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    @ oln,

    The scanmaxx is purchased second hand, i only have the device without manual. Unfortunately i cannot get the manual on their site too... The menu function has no response when i press it, but from the website/brochure, it is advertised as automatic scanning. I do not have trouble using the scanmaxx though, it's only it sometimes produce some distorted output. The only confusing part is that, if the scanmaxx do take it composite video in the "G" port, what about the 5 BNCs to VGA cable ? I'm sure that is just a simple connection of wire to VGA pins right ? But this wire also works if connecting to the green color BNC port. I'm trying to figure this out.

    @Jagabo

    Hi Jagabo, thanks for your response. If the composite to VGA device do not work, it can only be explain that the source isn't composite video, or maybe some parameters the converter is not supported ? I'm unsure. But like I said, since the 'G' port of the 5 BNCs to VGA cable works, do you think it's common that the sync line is combined in the 'G' wire of the cable ? I thought this kind of wire is simply connecting each BNC wire to the 5 pins of the VGA pins.

    @smrpix

    The DVI port from X-Ray is for Right monitor. I want the content from left monitor.

    Edit: I bought a VGA to composite video converter just to test out if the 3 converters I have is able to convert composite video. Below is the converter i bought

    Image
    [Attachment 50913 - Click to enlarge]


    The result is all 3 is able to convert the composite video, but results are varied between 3.

    5 BNCs to VGA produce blurry green tint video as shown below

    Image
    [Attachment 50914 - Click to enlarge]


    scanmaxx produce blurry black and white video

    Image
    [Attachment 50915 - Click to enlarge]


    composite to VGA converter produce the least blur colored video

    Image
    [Attachment 50916 - Click to enlarge]



    But for the X-ray machine, the 5 BNCs to VGA and scanmaxx do not produce such blurry video though, it's quite clear as compared to the result here.
    Last edited by diontan; 18th Nov 2019 at 21:46.
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  8. Originally Posted by diontan View Post
    Hi Jagabo, thanks for your response. If the composite to VGA device do not work, it can only be explain that the source isn't composite video, or maybe some parameters the converter is not supported ?
    Composite video normally means TV composite video. TV is a much lower bandwidth signal than the lowest computer VGA resolution. So VGA monitors could not sync to composite video, and old analog TVs could not sync to VGA video. A composite-to-VGA converter like the one you linked to will not be able to sync to a VGA G+HV signal because it's expecting the lower bandwidth TV signal.

    Originally Posted by diontan View Post
    But like I said, since the 'G' port of the 5 BNCs to VGA cable works, do you think it's common that the sync line is combined in the 'G' wire of the cable ?
    Like I said G+HV is typical for a VGA output because many computer monitors only had three inputs: R, G and B.

    What you need is a VGA capture device.
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  9. Member Cornucopia's Avatar
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    Also, an X-ray machine does not / would not output color (think about how xray scanning works...). Bnc to monitor does not necessarily mean "standard consumer tv monitor", especially in this context. Look at your manuals - it should specify the monitor specs.
    Most likely, it is square pixelled, grayscale. So the closest you would get with that existing converter is what you have done connecting the cable to G/hv. Software adjustment can fix your aspect ratio issue as well as drop the erroneous color.
    But it probably would be smarter getting a dvi splitter/da so you have 2 straight, clean dvi outputs.

    Scott
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    @ jagabo, any recommendation on which VGA capturing device that accept BNC input I should get ? I agree with u that the video out from x-ray might not be composite video.

    @ Cornucopia, I understand what you mean on the video output from X-Ray might not be composite. However, what's the relationship between composite video and the G/HV ? somehow composite video is able to be converted via the scanmaxx or 5 BNCs to VGA cable through my own testing though, although it's blurry, but i thought composite video and RGB is totally different things right?
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