GStreamer

Pipeline examples

Take an image

gst-launch-1.0 -v v4l2src num-buffers=1 device=/dev/video3 ! jpegenc ! filesink location=capture.jpeg

Record a video

gst-launch-1.0 v4l2src device=/dev/video3 ! imxvideoconvert_g2d ! "video/x-raw, height=640, width=480, framerate=30/1" ! vpuenc_h264 ! avimux ! filesink location='/home/user/video.avi'

Streaming examples:

• On PC: RX Pipeline to receive the stream from the NavQPlus AI/ML companion computer:

gst-launch-1.0 udpsrc port=50000 ! "application/x-rtp, media=(string)video, clock-rate=(int)90000, encoding-name=(string)H264, payload=(int)96" ! rtph264depay ! decodebin ! queue ! autovideosink

• On NavQPlus (e.g. from SSH connection):

gst-launch-1.0 v4l2src io-mode=dmabuf device=/dev/video3 ! "video/x-raw,width=1920,height=1080,framerate=(fraction)30/1" ! vpuenc_h264 ! h264parse ! rtph264pay ! udpsink host=10.0.1.101 port=50000

• Video Test Source instead of camera: gst-launch-1.0 videotestsrc ! "video/x-raw,width=640,height=480,framerate=(fraction)10/1" ! vpuenc_h264 ! h264parse ! rtph264pay ! udpsink host=10.0.1.101 port=50000

• Camera Tuning: 1) Get the video subdevice using:

media-ctl -p /dev/media0

remember the sub-device of the camera ( ov5645tn) in the media video chain, e.g. /dev/v4l-subdev2

2) List the available user and camera controls and try them out (e.g. contrast, saturation, auto white balancing etc.):

v4l2-ctl -l -d /dev/v4l-subdev2

• Streaming and Storing to a h264 compressed file simultaneously including text overlays for 30 seconds:

gst-launch-1.0 v4l2src io-mode=dmabuf device=/dev/video3 num-buffers=900 ! "video/x-raw,width=1920,height=1080,framerate=(fraction)30/1" ! tee name=t ! queue leaky=1 ! textoverlay text="Live" ! vpuenc_h264 ! h264parse ! rtph264pay ! udpsink host=10.0.1.101 port=50000 sync=false t. ! queue ! textoverlay text="recorded" ! vpuenc_h264 ! mpegtsmux ! filesink location=record_$(date +"%Y-%m-%d_%T").mp4

Note: The VPU is encoding two streams in parallel as we have different text overlays on the live stream and the recorded file

Note on hostapd

To avoid needing to set up a Wi-Fi router hostapd can be installed so that the NavQPlus acts as an access point. Additionally a DHCP server can be configured. This way you can directly connect to the WiFi network spawned by the NavQPlus:

Shown highlighted below, the IP address 10.0.1.101 is coming from the DHCP server on the NavQPlus.