v4l2src doesn't launch always - seems to be a clock issue

[Dwight Kulkarni]

Hi Nicolas,

The application is just the command line gst-launch-1.0   with pipeline of
v4l2src ----> autovideosink.   The earlier log files that we shared had
some other pipeline elements also launched via gst-launch-1.0 at the
command line which we can be removed because problem is originating at
v4l2src.

We have written a custom driver for the camera board. As these are
gstreamer messages they would be downstream from the driver.

There is a 4 lane MIPI signal and clock coming out of the camera sensor,
which is then processed by the driver.

There are actually 2 hardware components which is the CPU board and the
camera board. If we change for example one CPU board with the same camera
board, it will give a different result running the identical clone of the
operating system.

However, from same CPU board to camera board there is a statistical
similarilty. For example, if one camera board works 7/10 times, it is
consistently working 7/10 times if we try again another 10 times.

Another observation is that once the stream starts working, it stays
working, and if it fails, it will stay failed.

This seems to indicate some issue during initialization or negotiation. One
possibility is that there is maybe an unhandled exception or some data, and
this occurs with some frequency during the stream startup but on some
boards not all. Another possibility is there is clock or signal data that
is barely within the operating parameters and during boot up some of the
time it is outside those constraints, when the application or the driver is
trying to sample the clock maybe it is not finding it in those cases ?

We had earlier found that our input clock was at 1.2 Volt logic level not
1.8 Volt, so this can cause a problem maybe in triggering the sensor,
sometimes suble variations in the peaks could be triggering it and other
times not. We then tried two hardware changes one with external oscillator
at 1.8 volt and one drawing CPU clock boosted to 1.8 volt and it didn't
make any difference.

However, we haven't yet ruled out the output clock coming from the camera
board, or something going wrong in the driver, or downstream from the
driver in gstreamer.




On Fri, Sep 15, 2023 at 6:42 PM Nicolas Dufresne <nicolas at ndufresne.ca>
wrote:

> Le vendredi 15 septembre 2023 à 17:18 -0400, Dwight Kulkarni via
> gstreamer-devel a écrit :
>
> Hi all,
>
> With regards to earlier post about v4l2src, we have narrowed down the
> problem to one set of logs.
>
> Going through the logs, I am finding this DEBUG message keeps repeating
> when the pipeline stream* isn't playing.*
>
> 0:00:18.777042366  1895 0xaaaafba09600 DEBUG               basesink gstbasesink.c:5408:default_element_query:<autovideosink0-actual-sink-wayland> position query in format time
> 0:00:18.777067992  1895 0xaaaafba09600 DEBUG               basesink gstbasesink.c:5342:gst_base_sink_get_position:<autovideosink0-actual-sink-wayland> *position in wrong state, return -1*
>
>
>
> When the pipeline is working properly, I get the following message, instead
>
> 0:00:13.244891490  1917 0xaaab01cec600 DEBUG               basesink gstbasesink.c:5408:default_element_query:<autovideosink0-actual-sink-wayland> position query in format time
> 0:00:13.244928990  1917 0xaaab01cec600 DEBUG               basesink gstbasesink.c:5200:gst_base_sink_get_position:<autovideosink0-actual-sink-wayland> using clock and base time 0:41:42.435970707
>
>
>
> Can anyone comment on what this error might mean ?  Seems like the stream
> is not able to initialize the clock for some reason ?
>
>
> Its application fault, it means a position query was issued before the
> sink reached PAUSED state. Some application will just retry later, some
> actually wait properly for playing state to be reached. Maybe you could
> help us understand what your application is doing with this query ?
>
> Nicolas
>
>
>
>
>
> --
> Sincerely,
>
> Dwight Kulkarni
>
>
>

-- 
Sincerely,

Dwight Kulkarni
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <https://lists.freedesktop.org/archives/gstreamer-devel/attachments/20230916/78042efb/attachment.htm>