need help to understand the pipeline

[Peter Maersk-Moller]

Hi

Assuming your pipeline actually runs, I can assure you that your
videoconvert does not take jpeg as input and you have specified video/x-raw
as format (a family of raw formats). So v4l2src does output raw video and
not JPEG. Now I don't know your platform and maybe your v4l2src
implementation has the ability to read JPEG/MJPEG from the camera and
convert it to raw video on your specific hardware platform, but as such,
you have no JPEG in your pipeline. And I am assuming your pipeline is
running. Is it?

Now run your pipeline again with the '-v' flag set for gst-launch-1.0
pipeline and post ALL the output here. We can then identify what each
module take as input and what they output.

P

On Fri, Jul 16, 2021 at 2:15 PM niXman via gstreamer-devel <
gstreamer-devel at lists.freedesktop.org> wrote:

>
>
> hello Maersk-Moller,
>
> thank you very much for your answer!
> but I have a few questions because something is not clear to me...
>
> On 2021-07-16 10:52, Peter Maersk-Moller via gstreamer-devel wrote:
> > Hi niXman
> >
> > You are in fact not retrieving JPEG encoded frames from your camera.
> > Apparently your camera also supports a raw video format.
>
> according to the documentation, the Omnivision OV5640 chip gives frames
> in JPEG.
> please explain why you think it is not so? how can i check in what
> format i am receiving frames actually?
>
> > Most likely this raw format is some sort of YUV format. You can find
> > out by
> > adding '-v' to gst-launch-1.0 and look for the format accepted by the
> > videoconvert sink pad.
>
> I tried, but I don't understand what I see...
> when I specify "video/x-raw" in the output it is also "video/x-raw", and
> when I specify "image/jpeg" in the output it is also "image/jpeg".
> how can this be? the camera sends frames in both formats and gstreamer
> just chooses which format to use? or how?
>
>
>
> best!
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