big delay of 13 seconds to turn on the camera

[Sebastian Dröge]

On Tue, 2016-10-25 at 21:01 +0200, ano ona wrote:
> Hi, i'm new to gstreamer, played a little with the command line and
> the C API. I have many issues, but don't know if it's coming from a
> bad usage, my distro, or the framework itself. Sorry if the answer is
> obvious.
> 
> My goal is to build a camera triggered by a PIR sensor on the
> beagleboard black (BBB).
> 
> I made test on laptop and the BBB.
> 
> Here, i'll address an issue, i have on both the BBB and the laptop.
> Both are on ArchLinux.
> 
> So, i'll start with one that is quite annoying knowing my goal.
> 
> I have this problem, on laptop and BBB, with cmd-line and API.
> 
> GStreamer Core Library version 1.9.90
> kernel 4.8.4-1-ARCH
> 
> Here, is a link of the log of the command :
> 
> gst-launch-1.0 v4l2src device=/dev/video0 ! 'video/x-
> raw,format=YUY2,width=960,height=544,framerate=20/1' !  jpegenc  !
> rtpjpegpay !  fakesink &> log.txt
> 
> http://pastebin.com/4WbpyCau
> 
> U can see at line 151-152 the time it takes : 13scec
> 
> maybe it's gst_v4l2_object_probe_caps that takes this time ?

Take a look at a full debug log to check where time is spent, or use a
profiler for that. A debug log should be enough for this huge amount of
time though.

It could be anything really. You probably also want to add a queue
after v4l2src in your pipeline to make it possible that v4l2src and the
jpeg encoding can run on different CPU (cores).


It could be the probing though, maybe we run into a tricky case here
and probe too many formats, which might be slow with your camera to do.

-- 
Sebastian Dröge, Centricular Ltd · http://www.centricular.com
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