[PD] [OT] get video stream with pdgst from XIMEA camera

Jack jack at rybn.org
Fri Aug 23 12:17:08 CEST 2013


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Hello,

Le 22/08/2013 21:03, IOhannes zmölnig a écrit :
> On 08/22/2013 08:40 PM, Jack wrote:
>>
>> $ cat /sys/devices/virtual/video4linux/video1/format
>> GREY?30:1280x1024 at 30
>>
>> I expect 60 fps.
>> If i set :
>> $ v4l2-ctl -d /dev/video1 -p 60
>> or
>> $ v4l2-ctl -d /dev/video1 -p 1
>> It doesn't change anything.
>> Do you know if there is a possibility to get this frame rate (60 fps) ?
>> Is it a limitation using videoloopback ?
>
> no.
> v4l2loopback does not know nor care about frames or formats.
> it simply passes the frames from one application to another. there is no
> colorspace-conversion of resampling or the like involved.
OK.
>
>
>
> it's gstreamer that doesn't set the framerate correctly.
>
> you could force it by running:
>  $ echo "@60" | sudo tee /sys/devices/virtual/video4linux/video1/format
>
> in practice i don't think that this framerate setting will do much.
Yes, it doesn't change anything.
>
>
>
>> For info, i get 60 fps when I use the application streamViewer.
>
> how do you know?
It is written in the top window border : "Acquisition [ cptured: 2854,
skipped: 1, fps : 61.40 ]"
Seeing the video capture in the Gem window, i guess it is at 60 fps.
So, in this case, information about framerate return by :
$ v4l2-ctl --all -d /dev/video1
or
$ cat /sys/devices/virtual/video4linux/video1/format
is incorrect.
Thank you for your help IOhannes, now I can get the stream from a XIMEA
camera in Gem.
Do you think, it will be much better/faster/stable to get a v4l2 driver
from XIMEA than to use a pipe with gstreamer/v4l2loopback ?
++

Jack


>
>
> fdsmard
> IOhannes
>
>
>
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