Hi

One of our productions has a lot of user generated content (Images, Video and Audio - mainly from smart phones), and its just not feasible to keep adding inputs to VMIX as new content arrives from the viewers during a production.

We have a separate 'content moderator' who prepares incoming content (rotates, colour adjusts etc.) and uses as separate PC with a second display running VLC that was originally scan converted and placed on an SDI input of a traditional Vision Mixer. Since adopting VMIX we have done away with the scan converter and now use Desktop Capture.

Thanks to the very kind people at Newtek part of their tool set includes a plugin for VLC that allows the video output to be directly renderd to an NDI channel without the need to 'Desktop Capture' it. This is a much cleaner solution, however there is one small issue.

With desktop capture (and i am referring to the whole desktop) the image currently being displayed is for example a portrait image. VLC will place the image in the centre of the frame horizontaly, scaling it to the maximum height of the frame (1080), but maintaining aspect ratio of the image by placing black borders to the left and right of the image. Conversely if I try displaying a wide panoramic image, VLC will centre the image verticaly in the frame, scaling the maximum width of the frame (1920) but maintaining the aspect ratio of the original image.

The result is it doesn't matter what image or video I throw at it - it will always render the whole image, maintaining the aspect radio of the source within the confines of my 1920 x 1080 output display by padding with black. I can then 'Luma' key this image onto a background in VMIX

The issue is when we use the NDI plugin to directly render the VLC output, instead of using 'full' desktop capture, every image no mater what its original resolution or aspect ratio is stretched to fill the full framein both dimensions on VMIX. The net effect Short Fat People on portrait images, and tall thin ones on panoramic (or wide landscape) images.


This does not seem to be the case when using NewTeks NDI Monitor' software, which seems to be able to maintain aspect ratios correctly, displaying the full image withing a 16:9 frame.

VMIX needs to be able to 'dynamically' adjust the NDI input according to is resolution and aspect ratio, so that when 'source' is selected as the inputs aspect ratio, aspect ratio is maintained no matter what is thrown at its input.

I'm absolutely sure there are applications that will require aspect ratio to be hard set to 'Normal (4:3), Widescreen (16:9), or anamorphic (16:9 stretched to fill a 4:3 frame) - but when set to 'source' needs to be source, and if the source resolution and aspect ratio changes, even when the input is live, VMIX needs to compensate and change it on the fly.

There may be a way of setting VLC to always create a 19020 x 1080 frame, and centre the image within this before rendering to the NDI plugin - but for the life of me I cant find it, even it the dark underbelly of its advanced settings.



All The Best

Keith

Martin

Thanks for the reply, the issue could be with the way VLC renders to the NDI plug in. My source images are all taken using an iPhone. Nothing special. But I have tried regular 640 x 480 (4:3) type jpeg images, and when played out via VLC thru NDI, appear perfectly rendered in NewTek's NDI Monitor, but stretched to the full 16:9 frame in VMIX.

It did seem a bit odd, as I know your using the same NDI library as I am using.

I'm quiet happy to send over some samples, but have tried about 60 images from different sources and if not in a 16:9 format are always stretched to full frame.

Keith

Since we have had issues with VLC/NDI Plugin (it's a VLC issues sending webcam video and separate audio source), we are not using a 2nd copy of vMix. We use the 2nd copy for both recording and for bringing up recorded videos and webcams. Some are DV and vMix on the receiving PC is centering those in the PIP window() just fine. I can mix 16:9, 4:3, basically some odd ones and it seems vMix is doing it right, at least in this config. I actually had 4 PIPs using all 4 overlays with 4 vids, different formats.

Try a brand new vMix session and add the NDI input from scratch.
If the position zoom settings for the input are adjusted in any way this will override the automatic aspect ratio correction vMix applies.