v4l2src hangs forever

[Frederik]

Hi,
I experience that my camera stops before it's even started. The error is not
100% reproducable, and is even harder to reproduce when running with
loglevel set to debug.
The last entry in the log from v4l2 is
gst_v4l2_buffer_pool_acquire_buffer:<v4l2src0:pool:src> acquire
After that, I hear nothing from the pipe at all.

Can anyone help me ?

Thanks

/Frederik

gstreamer.dump
<http://gstreamer-devel.966125.n4.nabble.com/file/t378180/gstreamer.dump>  



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[Nicolas Dufresne-5]

Le lundi 04 février 2019 à 06:32 -0600, Frederik a écrit :
> Hi,
> I experience that my camera stops before it's even started. The error is not
> 100% reproducable, and is even harder to reproduce when running with
> loglevel set to debug.
> The last entry in the log from v4l2 is
> gst_v4l2_buffer_pool_acquire_buffer:<v4l2src0:pool:src> acquire
> After that, I hear nothing from the pipe at all.
>
> Can anyone help me ?

Sure, which version of GStreamer is this ? Did you check your kernel
log to make sure you camera driver haven't crashed ?

>
> Thanks
>
> /Frederik
>
> gstreamer.dump
> <http://gstreamer-devel.966125.n4.nabble.com/file/t378180/gstreamer.dump>  

I checked in that dump, but I don't see the v4l2 traces. Try
reprocucing with:

  GST_DEBUG="v4l2*:7" ...

>
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[Frederik]

Hi Nicolas,
thanks for your fast reply.
GStreamer version is 1.12.3.
Camera driver seems ok, lsusb shows a UVC camera, and I can read out camera
settings from /dev/video0
I have attached a trace dump, seems like v4l2 gets stuck in polling device
gstreamer_trace.dump
<http://gstreamer-devel.966125.n4.nabble.com/file/t378180/gstreamer_trace.dump>  



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[Nicolas Dufresne-5]

Le lun. 4 févr. 2019 08 h 27, Frederik <[hidden email]> a écrit :

Hi Nicolas,
thanks for your fast reply.
GStreamer version is 1.12.3.
Camera driver seems ok, lsusb shows a UVC camera, and I can read out camera
settings from /dev/video0
I have attached a trace dump, seems like v4l2 gets stuck in polling device
gstreamer_trace.dump
<http://gstreamer-devel.966125.n4.nabble.com/file/t378180/gstreamer_trace.dump> 

It's waiting for the kernel to give back a buffer. If there is no error in dmesg, then I don't know what is going on. Maybe one of these camera for which 1.12 was crashing their firmware ? Would be nice to give 1.14 a try.

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[Frederik]

Yes, it seems like it's waiting forever in
gstv4l2bufferpool::gst_v4l2_buffer_pool_poll
If I add a pre condition step (open /dev/video1 and then close /dev/video1
)before starting the stream it's seems to work.

Are there many improvements from 1.12 to 1.14 regarding v4l2  ?



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[Nicolas Dufresne-5]

Le lundi 04 février 2019 à 08:36 -0600, Frederik a écrit :
> Yes, it seems like it's waiting forever in
> gstv4l2bufferpool::gst_v4l2_buffer_pool_poll
> If I add a pre condition step (open /dev/video1 and then close /dev/video1
> )before starting the stream it's seems to work.
>
> Is there many improvements from 1.12 to 1.14 regarding v4l2  ?

It's documented here, https://gstreamer.freedesktop.org/releases/1.14/

One to note is in 1.14.2, "v4l2bufferpool: Only return eos for M2M
devices not v4l2src when buggy driver sends empty buffer". That seems
like plausibly your case, some code made for decoders ended up causing
the source thread to stop silently.

Nicolas

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[Frederik]

That sounds interesting. I will try to see if it's possible to upgrade to
1.14.
Thanks for your help !

Best regards
Frederik



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