[aravis] Re: Debugging latency & long pause issues with Blackfly camera...
- From: Patrick Doyle <wpdster@xxxxxxxxx>
- To: aravis@xxxxxxxxxxxxx
- Date: Wed, 16 Apr 2014 09:39:23 -0400
Actually, after writing my long email, my long email, I (finally)
decided to look at the PointGrey documentation. Scanning through
their Technical Reference manual, I see that they offer the ability to
encode the timestamp, gain, exposure, brightness, etc… in the first N
bytes of each image transmitted. They then go on to document the
timestamp format that gets encoded in the image as being a 32 bit
integer, where the top 7 bits represent seconds, and wrap around every
128 seconds (presumably incrementing the high order 32 bit register
when they do so, as I observed). The next 13 bits contain a 13-bit
"Cycle Count" in units of 125 uS that increments from 0 to 7999. And
the lower order 12 bits contain a "Cycle Offset", which I don't
understand yet. It seems reasonable that the out-of-band timestamp
would follow the same format as the in-band data.
Scanning briefly the 3 data logs I collected, I see that the 13 bit
Cycle Count value increments by 100 for each frame received when I
(think I) configured the camera at 60 fps, and by 200 for my 30fps
log.
Hmmm…
--wpd
On Wed, Apr 16, 2014 at 9:22 AM, Emmanuel Pacaud <emmanuel@xxxxxxxxx> wrote:
> Hi,
>
> Le mercredi 16 avril 2014 à 09:02 -0400, Patrick Doyle a écrit :
>> I can think of 3 possibilities:
>> 1) Handle timestamps from BlackFly cameras as a special case within
>> the Aravis framework.
>> 2) Extend the Aravis framework to allow it to report raw timestamps
>> received from a camera and write my own gstreamer plugin to convert
>> Blackfin timestamps to ns.
>> 3) Do something smarter suggested by one of you.
>
> A last possibility is to contact PointGrey support and submit what you
> have observed. It can be a bug in Aravis, but also in the camera
> firmware. If it is the latest, a fix in the firmware would be the best
> solution.
>
> Cheers,
>
> Emmanuel.
>
>
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