Add webcam streaming #34
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Per internal communication, webcams are only available for access when the Virtual Machine's USB Controller is xHCI (USB 3.0) instead of the default OHCI (USB 2.0). I have set the development VM's USB Controller to xHCI. Great find! |
image-toolkit/sbin/startup.sh
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| }" & | ||
| CLVC_PID=$! | ||
| # Monitor the process and device | ||
| while [[ -e "/dev/video$DEVICE_NO" ]] && ps -p $CLVC_PID > /dev/null; do |
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You should monitor /dev/video with inotifywait (for example, inotifywait -e delete_self /dev/video0 will exit when /dev/video0 is disconnected) and wait -n <pidlist> (wait for any in to finish).
Monitoring /dev/video0 by repeatedly polling could miss quick reconnection events (for example, a contestant accidentally touching the webcam's wire).
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Thanks for your suggestion. I will update the code accordingly.
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We will use udevadm (from udev package already installed in Ubuntu 22.04) to listen for webcam-related events. |
Using fixed keyframe interval significantly reduce stream latency and reduce *.ts fragment file size.
image-toolkit/sbin/startup.sh
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| udevadm monitor --udev -s video4linux | while read -r line; do | ||
| if [[ "$line" == *"remove"*"/video4linux/video$DEVICE_NO"* ]] ; then | ||
| echo "Device unplugged, proceed to kill cvlc" | ||
| kill $CLVC_PID 2>/dev/null || : |
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This logic is kinda complicated, and if VLC catch SIGTERM and fails to exit (like during startup), we'll be in a deadlock.
Let's make the udevadm process exit on device disconnect, then use wait -n to wait for the first process among the two to exit. If udevadm exits, we kill vlc. Exit udevadm also clears the event queue, so that consecutive connect-disconnect will not make us restart vlc more time than is necessary.
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Also, for good measure, kill vlc with SIGKILL (kill -9) if it's not killed after a while (wait with something like timeout wait $CVLC_PID). Also, starting udevadm before vlc would be safer.
…vice remove event
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…using exit on error
image-toolkit/sbin/startup.sh
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| @@ -53,6 +53,49 @@ vlc_restart_loop() { | |||
| done | |||
| } | |||
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| webcam_stream_loop() { | |||
| VIDEO_DEVICE_NO=0 | |||
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Due to obsproject/obs-studio#3003 (webcam numbering may differ after reconnection), use devices in /dev/v4l/by-id
Increases robustness of webcam_stream_loop
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For audio streaming, we will have a configurable For ease of configuration, the |
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Use vlc to stream from /dev/video0 to rtmp://localhost/live/webcam and use ffmpeg-webcam.service to save local chunks.