[ros-users] Firewire camera synchronization

[Thomas Moulard]

On Thu, Dec 2, 2010 at 9:21 PM, Jack O'Quin <jack.oquin at gmail.com> wrote:
> On Thu, Dec 2, 2010 at 11:48 AM, Blaise Gassend <blaise at willowgarage.com> wrote:
>>> Just to make things clear: it will still not be a good solution for
>>> firewire camera users
>>> as images will still be unsynchronized. Only one process grabbing two
>>> cameras will solve
>>> this issue with high end firewire cameras such as the Flea2 which send
>>> automatically synchronized frames
>>> when the acquisition is done atomically.
>
> What DC1394 command triggers this acquisition?
>
> Or, is it something device-specific?

Yes, this is done by the device.

>From the Flea2 documentation:
« Automatic Synchronization
Multiple Flea2 cameras networked on the same IEEE-1394 bus are
automatically synchronized to within 125µs (maximum deviation)
of each other, and can synchronize across buses using Point Grey
MultiSyncTM software. »

http://www.ptgrey.com/products/flea2/index.asp

There is nothing in the userland which has to be used to enable the
synchronization, it
is automatic as long as the acquisition of the two images is done fast
enough (which
separate process cannot achieve).

>> OK, I agree with you here. If a combined driver can easily cause the
>> cameras to be triggered simultaneously then there is value in adding
>> support for this to the camera driver itself.
-- 
Thomas Moulard
http://www.linkedin.com/in/moulard