[libcamera-devel] [PATCH] README: Extend gstreamer examples

[Laurent Pinchart]

On Wed, Mar 16, 2022 at 11:36:30PM +0530, Umang Jain via libcamera-devel wrote:
> On 3/16/22 19:43, Kieran Bingham via libcamera-devel wrote:
> > There have been many reports of facing difficulties with the gstreamer
> > element and getting the libcamerasrc to successfully negotiate with
> > other gstreamer elements.
> >
> > This is often due to the current limitations on colorimetry and frame
> > rate support in the element, and can usually be worked around by
> > specifying those explicitly in the caps.
> 
> Yes, I was going to take a look at it earlier but alas didn't any 
> time-slot. Colorimetry is a low-hanging fruit between the two it seems.
> 
> > Provide a tested example to capture, encode, and stream images as jpeg
> > to a remote device in the gstreamer section of the getting started
> > readme.
> >
> > Signed-off-by: Kieran Bingham <kieran.bingham at ideasonboard.com>
> > ---
> >
> > Technically this pipeline will stream without specifying the colorimetry
> > but the purpose is to add an example with both framerate, and
> > colorimetry explicitly listed to help people debug their pipelines
> > themselves.
> 
> Yes, great.
> 
> >   README.rst | 19 +++++++++++++++++++
> >   1 file changed, 19 insertions(+)
> >
> > diff --git a/README.rst b/README.rst
> > index ca8a97cbd71b..7abbc9e7a9ae 100644
> > --- a/README.rst
> > +++ b/README.rst
> > @@ -139,6 +139,25 @@ the video device provider) and libcamerasrc (for the operation of the camera).
> >   All corresponding debug messages can be enabled by setting the ``GST_DEBUG``
> >   environment variable to ``libcamera*:7``.
> >   
> > +Presently to prevent element negotiation failures it is required to specify the
> 
> s/Presently/Presently,/ maybe?
> 
> > +colorimetry and framerate as part of your pipeline construction. For instance
> 
> s/instance/instance,/
> 
> Reviewed-by: Umang Jain <umang.jain at ideasonboard.com>

Reviewed-by: Laurent Pinchart <laurent.pinchart at ideasonboard.com>

We may want to move documentation for the GStreamer element to a
separate file at some point.

> > +to capture and encode as a JPEG stream and receive on another device the
> > +following example could be used as a starting point:
> > +
> > +.. code::
> > +
> > +   gst-launch-1.0 libcamerasrc ! \
> > +        video/x-raw,colorimetry=bt709,format=NV12,width=1280,height=720,framerate=30/1 ! \
> > +        jpegenc ! multipartmux ! \
> > +        tcpserversink host=0.0.0.0 port=5000
> > +
> > +Which can be received on another device over the network with:
> > +
> > +.. code::
> > +
> > +   gst-launch-1.0 tcpclientsrc host=$DEVICE_IP port=5000 ! \
> > +        multipartdemux ! jpegdec ! autovideosink
> > +
> >   .. section-end-getting-started
> >   
> >   Troubleshooting

-- 
Regards,

Laurent Pinchart