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

[Umang Jain]

Hello Kieran,

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>

> +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