[Video] The HD setup proposal
Tim Ansell
mithro at mithis.com
Sun Jun 23 19:07:22 EST 2013
These questions are now answered in the new FAQ page!
https://github.com/timvideos/HDMI2USB/wiki/FAQ
Appreciate it if people added more information there...
Tim
On 23 June 2013 15:35, Tim Ansell <mithro at mithis.com> wrote:
> > 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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