GStreamer use cases with libcamera

Pipeline negotiation

If your pipeline fails to negotiate, use gst-validate-1.0 in place of gst-launch-1.0 for more information.

Then start with the basics and enable gst debug trace for warnings and errors. Prefix your launch line with GST_DEBUG=2 and if that's not sufficient, go noisy with: GST_DEBUG="CAPS:5"

Look for some lines saying "not compatible"

"reason not-negotiated (-4)" is usually cause by two of more links that aren't compatible to each other, for cameras its most of the time pixel format related

Measure framerate from the camara

gst-launch-1.0 libcamerasrc ! fpsdisplaysink video-sink=fakesink text-overlay=false -v

Multiple streams:

(Not fully tested/guaranteed)

pi@mercury:~ $ cat multistream.sh
#!/bin/sh

export GST_DEBUG=5
export GST_DEBUG_FILE=multistream.log

gst-launch-1.0 \
	libcamerasrc name=src \
		src.src ! queue ! videoconvert ! autovideosink \
		src.src_0 ! queue ! videoconvert ! autovideosink

RTP Streaming

Test with videotestsrc (courtesy of Triodes on #libcamera)

gst-launch-1.0 -vvvv \
	videotestsrc pattern=ball ! \
	'video/x-raw,width=1920,height=1080,framerate=30/1,format=NV12' ! \
	v4l2h264enc ! 'video/x-h264,level=(string)4.2,profile=baseline' ! \
	rtph264pay config-interval=-1 aggregate-mode=zero-latency ! \
	udpsink host=127.0.0.1 port=8004

And then with libcamerasrc

gst-launch-1.0 -vvvv \
	libcamerasrc camera-name="/base/soc/i2c0mux/i2c\@1/imx519\@1a" ! \
	'video/x-raw,width=1920,height=1080,framerate=30/1,format=NV12,interlace-mode=progressive' ! \
	v4l2h264enc ! 'video/x-h264,level=(string)4.2,profile=baseline' ! \
	rtph264pay aggregate-mode=zero-latency config-interval=-1 ! \
	udpsink host=127.0.0.1 port=8004

Note that currently the gstreamer element for libcamera might need explicit specification for the following properties:

• colorimetery
• framerate
• interlace-mode

For X264: x264enc tune=zerolatency

Tests with pipewire gstreamer pipelines:

    Robert Mader commented on a discussion: https://gitlab.freedesktop.org/pipewire/pipewire/-/merge_requests/1455#note_1697993
    
    All you'll need to change is the one line in `xdp-camera.py`:
    ```
    pipeline = Gst.parse_launch('pipewiresrc fd=%d ! videoconvert ! xvimagesink'%(fd))
    ```
    ->
    ```
    pipeline = Gst.parse_launch('pipewiresrc fd=%d ! videoconvert ! videoflip video-direction=auto ! xvimagesink'%(fd))
    ```
    
    While on it you could replace it with something like:
    ```
    pipeline = Gst.parse_launch('pipewiresrc fd=%d ! videoconvert ! videoflip video-direction=auto ! gtksink'%(fd))
    ```
    or even
    ```
    pipeline = Gst.parse_launch('pipewiresrc fd=%d ! glupload ! glcolorconvert ! gtkglsink rotate-method=auto'%(fd))
    ```
    
    `gtksink` instead of `xvimagesink` has the advantage of working on Wayland.