[SML] Qlab and video

[Andy Lang]

On Mon, Oct 19, 2015 at 1:28 PM Rick Clever via Stagecraft
stagecraft at theatrical.net <http://mailto:stagecraft@theatrical.net> wrote:

So if I have an HDMi out on my macbook and a thunderbolt port, can I
> use a thunderbolt adaptor to send to another monitor? For instance
> hdmi port to a sdi converter for one projector and thunderbolt port to
> hdmi out to another projector.

Yup, you can indeed. They’re two completely independent video outputs.
Subject to the final resolutions, and what your graphics card is actually
capable of pushing out them, but as a general concept, and for all but the
most extreme resolution needs, yeah.

Do they even make thunderbolt to sdi?

Yes, but….see my next answer

On Mon, Oct 19, 2015 at 1:43 PM Brian James via Stagecraft
stagecraft at theatrical.net <http://mailto:stagecraft@theatrical.net> wrote:

Never used it, but does this meet needs?
>
> https://www.aja.com/en/products/t-ta
> p
>
So, here’s the thing. There are two types of things that can connect to a
Thunderbolt port:

1) A Mini DisplayPort to *__* video adapter
2) Any of a bazillion Thunderbolt devices, which are basically external PCI
devices, to oversimplify quite a bit.

Type 1 will work with QLab, with no additional processor overhead. These
can be passive or active, and are usually found in composite, VGA, DVI, and
HDMI flavors. I don’t know of any that are SDI, as that’s a different scale
of conversion. These devices connect straight to the graphics card, and
show up as a display to the OS.

In type 2, there are a number of devices that provide SDI outputs. These do
NOT have dedicated GPU connections, and do NOT show up to the OS as a
display, and require dedicated drivers. They need to be explicitly
supported by software and will always have a heavier processing overhead,
since the graphics are rendered in the GPU, but then need to get passed
over to the output device, which involves some CPU lifting and another trip
through RAM.

Among these, BlackMagic are the only ones supported by QLab. Aja makes
fantastic devices, but their Thunderbolt gear is not compatible with QLab.

Now, you can, as I mentioned, use an outboard converter to convert the
output of a device of the first type to SDI. Aja and Blackmagic both make
such SDI converters, both of which are wonderful, and both of which will
work with QLab, since QLab doesn’t particularly care what you do with the
signal after it exits the computer (so long as there’s correct EDID/DDC
data presented to the computer. If that’s blocked, or otherwise mucked
with, things can get iffy. Aja and Blackmagic stuff should be fine, it’s
cheap gear like KVM extenders and switchers that don’t explicitly manage
EDID/DDC that you need to be wary of.

Hope that helps!

-Andy

—
Andy Lang
@SoundGuyAndy <http://twitter.com/SoundGuyAndy>
support at figure53.com
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