[AG-TECH] Re: AccessGrid For NetBSD

[Christoph Willing <willing@itee.uq.edu.au>]

On 11/08/2005, at 9:09 AM, Pritesh Shah wrote:
[snip]
> I have four capture cards. Each one has four inputs, three for
> Composite video type, and one for S-video. If i plugin two cameras in
> any of the inputs in one capture cards, the vic shows only one of the
> feeds, i'm guessing that this might be due to the fact that the
> grabber probes for the card and since its already sending a BUSY ioctl
> call, its just not able to capture the other video feed from the same
> card.
>
> Please correct me if i'm wrong here. Is this true for other OS's also.
> In one vic window its recognizing the card properly and showing up the
> video feed.
> In another vic window when menu > device is clicked that particular
> card's option is disabled, i mean its just grayed out and cannot be
> selected.
Pritesh,

I think there are really two issues here:

1. with the v4l (video for linux) driver, multiple inputs into a single 
card _can_ be selected using vic's Menu->Port switch

2. with the standard v4l driver, a particular card can only be selected 
_once_ using vic's Menu-Device switch. This is because the v4l driver 
only allows a physical device to be opened once. This means that a 
device which is already being used by another vic just doesn't appear 
in later instances of vic.

There is a newer driver, v4l2, which is capable of multiple opens of a 
single device. I'm not sure that a standard vic could take advantage of 
that though, since it wouldn't be accessing the v4l2 driver with actual 
v4l2 calls, rather plain old v4l calls (via the v4l2 driver's v4l 
compatibility layer).


chris


Christoph Willing                        Ph: +61 7 3365 8350
QPSF Access Grid Manager
University of Queensland