Example to stream video via ffmpeg

  • In this documentation(https://docs.modalai.com/docker-on-voxl/#access-to-mipi-cameras), last part, I get this code

    ffmpeg -an -sn -f rawvideo -pix_fmt nv21 -s:v 640x480 -i /opt/frame0 <output options>

    I already set up the docker with roskinetic-xenial_v1_0. Would you like to give an example to use FFmpeg? I want to stream the visual data and view such data on my laptop.

    I tried to save the video locally. but the system give me error

    ffmpeg -an -sn -f rawvideo -pix_fmt nv21 -s:v 640x480 -i /opt/frame0 output.mov
    /opt/frame0: Is a directory

    Thank you!

  • Dev Team

    @Ruijie-Geng In order to stream video to your ground control station you can do something similar to the following

    ffmpeg -an -sn -f rawvideo -pix_fmt nv21 -s:v 640x480 -i /opt/frame0 -f mpegts udp://GCS_IP:4242

    Where GCS_IP is the IP address of the ground control station (laptop) that you are connecting to.

  • Dev Team

    Also, you have to start the camera application that creates /opt/frame0 before starting the docker. Otherwise the docker will create /opt/frame0 itself as a directory and not as a pipe. If this happens, exit the docker, delete /opt/frame0, start the camera application, then start docker.

  • Thank you! I will have a trial to do that!

  • I meet another question that I try to run hello_hal3_camera -l /dev/frame0 before starting docker, but gives the error

    ~ # hello_hal3_camera -l /dev/frame0
    Camera id: 0
    Image width: 640
    Image height: 480
    Number of frames to dump: 0
    Frame FIFO: /dev/frame0
    Camera mode: preview
    SUCCESS: Camera module opened
    Camera Id: 0 Facing: 0
    Camera Id: 1 Facing: 1
    Error: Could not open named FIFO /dev/frame0
    Camera Id: 2 Facing: 1
    Camera HAL3 test is now running

  • Dev Team

    @Ruijie-Geng Can you please show the output of "ls -l /dev/frame0"?

  • Sorry for the late reply. I try the code again, the bug is gone. I can open /dev/frame0 correctly.

    Thank you very much

  • Hello, I can use FFmpeg to stream the data from /opt/frame0. And I can view something on my laptop. But the stream is something with green background. Do you meet a similar issue before?
    Does something wrong with my camera or the type of visual stream is not correct?


  • Dev Team

    Can you please send us the output of "ls -l /dev/frame0", the output showing hello_hal3_camera, and also ffmpeg?

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