[Video] The HD setup proposal

[Tim Ansell]

>
> > HDMI2USB has working board using the Digilent Atlys board. Looking at
> > first round of custom boards in November - really hoping to have devices
> > for LCA2014.
> >
> > See our progress at code.TimVideos.us <http://code.TimVideos.us>
>
> Just a quick couple of questions, Tim - I didn't understand the Digilent
> Atlys board specs enough to find answers.
>
> 1) Is the board capable of encoding analogue signals - DVI-A or VGA with a

DVI plug?
>

The base board only supports digital signals (mainly because the
development board we are using also only supports digital signals). It
supports HDMI, DVI and DisplayPort (in their many connector forms).

The board includes a powerful extension port which we will be developing
daughterboards for. We currently have a VGA daughterboard in development,
but yet to actually get anything like results yet.

The board also two serial ports and some GPIO pins which could be used for
PTZ Camera control or tally lights.

2) Does it produce compressed video?
>

It produces both;
 * mjpeg compressed video - Best for capture from a continuous source such
as a camera.
 * raw video - Best for capture of non-continuous or text heavy sources,
such as a presenter's slides.

Both are full 1024x768 or 720p resolution (depending on if the input is DVI
or HDMI).

The problem is that USB2.0 doesn't have enough bandwidth for raw video at
30fps, so if you want the higher frame rate you have to use the mjpeg
compression mode.

At the moment raw mode is about 10-15fps while the target for mjpeg mode is
a full 30fps/25fps (but we only get around 20ish at the moment, but that is
a software problem with our  JPEG encoder core we hope to solve rather than
a hardware issue).

The jpeg compression quality is controlled via a setting.


> 3) I see it has two HDMI ports in and two out - could this board record two
> cameras, or a camera and a laptop?
>

No, again USB 2.0 doesn't have enough bandwidth for recording two streams
at once. When we move to USB 3.0 this might become possible.

It can work as a matrix type device. It has two independent inputs (which
can come from different sources) and two linked outputs (ie they must
display the same output).

The idea would be

 Presenter's computer ----> HDMI Input 1 /          \ HDMI Output 1 --->
Speaker confidence screen
                                         | HDMI2USB |
 Podium computer      ----> HDMI Input 2 \          / HDMI Output 2 ---> In
room projector

This allows you to switch the in room projector to display something when
not presenting. It could have details about the room (IE name, what is up
next, etc) or something similar.

4) What kind of USB device does it present to the host?
>

The device appears as
 * UVC Webcam - This device is very common (pretty much every web-cam under
the sun uses this format) and well supported under Linux.
 * CDC Serial Port - This device allows you to control the various options
of the HDMI2USB and get status about which ports have active inputs, get
hot plug events and such.

If you get a chance could you explain where we could put this information
on the website/wiki so it's clear about what is supported?

Tim
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