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Usage Examples

stream to YouTube with ffmpeg

from Paul Gullett. post

ffmpeg -f lavfi -i anullsrc \
-f v4l2 -s 3480x1920 -r 10 -i /dev/video0 \
-vcodec libx264 -pix_fmt yuv420p -preset ultrafast \
-strict experimental -r 25 -g 20 -b:v 2500k \
-codec:a libmp3lame -ar 44100 -b:a 11025 -bufsize 512k \
-f flv rtmp://

As my knowledge of ffmpeg is weak, I simplified Paul's video pipeline.

 ffmpeg -f lavfi -i anullsrc -f v4l2 -s 1920x960 -r 10 -i /dev/video2 \
-vcodec libx264 -pix_fmt yuv420p \
 -b:v 2500k \
-codec:a libmp3lame -ar 44100 -b:a 11025 -bufsize 512k \
-f flv rtmp://$SECRET_KEY

YouTube panel

stream to another computer with gstreamer

by zdydek. post

in gst_viewer.c

pipe_proc = " rtph264pay name=pay0 pt=96 ! udpsink host= port=5000 sync=false ";

with gst-rtsp-server

./test-launch "( udpsrc port=5000 ! application/x-rtp, media=(string)video, clock-rate=(int)90000, encoding-name=(string)H264 ! rtph264depay ! h264parse ! rtph264pay name=pay0 pt=96 )"

Receive on ROS.

GSCAM_CONFIG="rtspsrc location=rtspt:// latency=400 drop-on-latency=true ! application/x-rtp, encoding-name=H264 ! rtph264depay ! decodebin ! queue ! videoconvert"  roslaunch gscam_nodelet.launch

Simplified computer to computer streaming with rtsp and gstreamer

This was tested going from an x86 machine to a Jetson Nano. The THETA Z1 is connected to the x86 Linux machine. It is not working with the Jetson as the sender.

On x86 computer sending THETA video.

Modify the pipeline in gst_viewer.c

This example has the IP address hardcoded in. Switch to a variable in your code.

pipe_proc = " decodebin ! jpegenc ! rtpjpegpay ! udpsink host= port=5000 qos=false sync=false";

modify pipeline

If you are looking for the IP address of the receiver, you can use arp-scan on the command line.


sudo arp-scan --interface=eth0 --localnet

On the receiving device, if the receiver is a NVIDIA Jetson Nano.

$ cat 
gst-launch-1.0 udpsrc port=5000 !  application/x-rtp,encoding-name=JPEG,payload=26 ! rtpjpegdepay ! jpegdec ! videoscale ! video/x-raw,width=640,height=320 ! nveglglessink

If you're on x86, change nveglglessink to autovideosink. You may want to make the width and height bigger as well.

streaming screenshot

Save to File

by Les Wu aka snafu666. post

Using the v4l2loopback capability and thetaV loopback example, here are 2 example gstreamer pipelines to grab the video:

As a lossless huffman encoded raw file:

gst-launch-1.0 v4l2src device=/dev/video99 ! video/x-raw,framerate=30/1 \
! videoconvert \
! videoscale \
! avenc_huffyuv \
! avimux \
! filesink location=raw.hfyu

And with default h.264 encoding on a Jetson:

gst-launch-1.0 v4l2src device=/dev/video99 ! video/x-raw,framerate=30/1 \
! nvvidconv \
! omxh264enc \
! h264parse ! matroskamux \
! filesink location=vid99.mkv

Pro tip, when you install v4l2loopback, use the video_nr option to create the video device somewhere high so it does not get displaced by PnP of other cameras.

The Huffyuv format is a large file format. VLC can play it.

Here's a shot of me playing a file that I generated with Les's pipeline.


On x86, this is the pipeline I used to save to a H.264 file.

$ gst-launch-1.0 v4l2src device=/dev/video2 ! video/x-raw,framerate=30/1 ! autovideoconvert ! nvh264enc ! h264parse ! matroskamux ! filesink location=vid_test.mkv

Example of playing file with gst-launch.

gst-launch-1.0 playbin uri=file:///path-to-file/vid_test.mkv


Community member Nakamura_Lab indicated that the he experienced significant frame loss when using lossless Huffman to save to file with the Xavier NX. He could save to file with H.264. However for his use case with multiple face detection, he needed higher resolution than provided by H.264.

He ended up using H.265 encoding to save to file, which provided both high quality and no frame loss.

gst-launch-1.0 v4l2src num-buffers=600 \
device=/dev/video0 \
! video/x-raw \
! nvvidconv \
! nvv4l2h265enc \
! h265parse \
! qtmux \
! filesink location=test.mp4 -e

Stream From Raspberry Pi 4 to a Windows PC

Thanks to Shun Yamashita of fulldepth for this solution to stream the Z1 video to a Raspberry Pi 4 with USB then restream it to a Windows PC.

This is the process:

  • Use GStreamer to stream UDP(RTP) to the Windows PC
  • Do not use H264 decoding on the Raspberry Pi as the Windows machine is handling it and it's likely that the RPi4 can't use hardware decoding for 4K H.264.
  • Tested with Raspberry Pi4 modelB with 4GB of RAM running Raspberry Pi OS

On the Raspberry Pi, the following was changed in the GStreamer pipeline in gst/gst_viewer.c.

src.pipeline = gst_parse_launch(
        " appsrc name=ap ! queue ! h264parse ! queue"
        " ! rtph264pay ! udpsink host= port=9000",