i.MX 6DL/Q SABRE-SD RTSP video and camera stream

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This article shows how to use the open source gstreamer1.0-rtsp-server package on i.MX6DL/Q SABRE-SD to stream video files and camera using RTSP protocol. It is based on i.MX_Linux_User’s_Guide Rev.4.1.15._2.0.0-ga, Multimedia section.
To install gstreamer1.0-rtsp-server in any Yocto Project image, please follow the steps below:

  1. Enable meta-multimedia layer:
    Add the following on your build/conf/bblayers.conf:
    BBLAYERS += "$"${BSPDIR}/sources/meta-openembedded/meta-multimedia"
    
  2. Include gstreamer1.0-rtsp-server into the image:
    Add the following on your build/conf/local.conf:
    IMAGE_INSTALL_append += "gstreamer1.0-rtsp-server"
    
  3. Run bitbake and mount your sdcard.

  4. Copy the binaries:
    Access the gstreamer1.0-rtsp-server examples folder:
    $ cd /build/tmp/work/cortexa9hf-vfp-neon-poky-linux-gnueabi/gstreamer1.0-rtsp-server/$version/build/examples/.libs
    

    Copy the test-uri and test-launch to the rootfs /usr/bin folder.

    $ sudo cp test-uri test-launch /media/USER/ROOTFS_PATH/usr/bin
    

Preparing the boards

The video/camera is streamed by the server (i.MX 6Q SABRE-SD at left) to the client (i.MX 6DL SABRE-SD at right), as the image below:

To connect more than one board to the minicom, open it with the command:

$ sudo minicom –s

Enter in the Serial port setup option and press A to set or change the PORTNUMBER, in “ttyUSB$PORTNUMBER”.

Be sure that the IPs are correctly set:

  • SERVER:
    => ifconfig eth0 $SERVERIP
    
  • CLIENT:
    => ifconfig eth0 $CLIENTIP
    

GStreamer pipelines

Video file example

  • SERVER:
    => test-uri file:///home/root/video_file.mp4
    
  • CLIENT:
    => gst-launch-1.0 playbin uri=rtsp://$SERVERIP:8554/test
    

    You can try to improve the framerate performance using manual pipelines in the CLIENT with the rtspsrc plugin instead of playbin. Follow an example:

    => gst-launch-1.0 rtspsrc location=rtsp://$SERVERIP:8554/test caps = 'application/x-rtp'  ! queue max-size-buffers=0 ! rtpjitterbuffer latency=100 ! queue max-size-buffers=0 ! rtph264depay ! queue max-size-buffers=0 ! decodebin ! queue max-size-buffers=0 ! imxv4l2sink sync=false
    

Camera example

  • SERVER:
    => test-launch "( imxv4l2src device=/dev/video0 ! capsfilter caps='video/x-raw, width=1280, height=720, framerate=30/1, mapping=/test' ! vpuenc_h264 ! rtph264pay name=pay0 pt=96 )"
    
  • CLIENT:
    => gst-launch-1.0 rtspsrc location=rtsp://$SERVERIP:8554/test ! decodebin ! autovideosink sync=false
    

    The rtspsrc has two properties very useful for RTSP streaming:

  • Latency: Useful for low-latency RTSP stream playback (default 200 ms);
  • Buffer-mode: Used to control buffer mode. The slave mode is recommended for low-latency communications.

Using these properties, the example below gets 29 FPS without a sync=false property in the sink plugin. The key achievement here is the fact that there is no dropped frame:

=> gst-launch-1.0 rtspsrc location=rtsp://$SERVERIP:8554/test latency=100 buffer-mode=slave ! queue max-size-buffers=0 ! rtph264depay ! vpudec ! imxv4l2sink

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