AV.io image shifted to right


#1

Hello,

I have several PCs, running Ubuntu 16.04 Linux, capturing video 24x7 from old Sun Sparc20 computers. The resolution is is 1152X900 @ 66Hz. I used the configuration utility to configure this as a user resolution. If I don’t do this, it gets recorded as 1024x768 (which is not really an issue).

The problem I have is that sometimes the image is shifted to the right by maybe 50-100 pixels. Sometimes the image is shifted only a little bit and sometimes it’s normal. It is unpredictable.

Another problem is that it does not capture the bottom 32 pixels so it is basically a 1152x864 image.

I’ve tried the various settings in the configuration utility but nothing seems to help. The units came with 3.1 Firmware and I’ve tried 3.3beta and 4.0 firmware but that was no help.

I understand this is an oddball resolution (for the modern world, anyway) but if my LCD monitors have no problem with it then I would think the AV.io should have no problem with it.

Any help would be appreciated.


#2

The AV.io HD has a list of VGA modes it attempts to match an incoming analog signal to, and unfortunately 1152x900@66hz isn’t one of them. I assume in this case it is capturing at the closest matching mode, which would be 1152x864. Unfortunately there isn’t a way to add a custom VGA mode with the AV.io HD, this is one of the features of the DVI2USB 3.0 which may be what you want to consider switching to for this particular use case. As a note, the user resolution you add is just for advertising to the application what it can support, and what the output will be. Also, the list of VGA modes only applies for analog signals, DVI or HDMI signals can be pretty much anything and they will work without issue.

The 50-100 pixel shift can be adjusted though, this is the AV.io HD trying to automatically determine the best capture parameters (and likely failing sometimes due to the unknown VGA mode). We make available the standard UVC device adjustments (intended for PTZ cameras) for horizontal and vertical adjustment, these will adjust the image captured which will allow you to fix this.


#3

Thanks for the quick reply.

I have the DVI2USB 3.0, as well. It has it’s own set of issues with this signal. It will not recognize the signal at all. This is due to the fact the the Sparc20 video uses sync on green. I have a box that goes between the computer and the capture device that moves the sync from green and puts it on the actual sync pin. The AV.io HD does not need this box. It is an Altinex DA1910SX. I’m pretty sure it’s out of production so I can’t rely on it in the future.

It would be great if Epiphan added support for the signal I need. I have seven AV.io HDs and will need to purchase more so I need to find a solution.

You did help me out by telling me about the UVC adjustments. I installed uvcdynctrl and I can now shift the image as needed. It’s a manual process so I’m investigating a way to automate this.

Thank you.


#4

There are a few differences between the AV.io HD and the DVI2USB 3.0, one being that the DVI2USB 3.0 can capture from a sync on green signal while the AV.io HD cannot. You describe the opposite behaviour, which is confusing and there must be something else going on.

You can certainly add the support for this signal in the DVI2USB 3.0, you would just need to go into our Capture Tool application under Capture -> Configure Device -> VGA Modes. Click the + button then specify the resolution and refresh rate and click OK. Of course you also have the options of clicking “Show technical details” and specifying all the timings for the signal if you have these.