Introduction: RASPBERRY PI Interrupt Driven Video Switching

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The goal of this project is to provide a dynamic display to a trashbox.

A main video is played in loop on the display.

Everytime an object is thrown into the trashbox, the display switches to a small video (featuring scrat, hyrax or minions)

The project is based on the excellent RPI video looper from Steven Hickson

http://stevenhickson.blogspot.ch/2014/05/rpi-video-looper-20.html

Step 1: Main Chalenge

The main chalenge was to switch from the main video to another video without delay.

omxplayer is definitely too slow for that kind of switching. I nearly gave up before I found a way to pause omxplayer and to launch the other video with hello_video.bin, bringing the switching delay to about nothin

The only drawback is that hello_video.bin can only read .h264 video format, while omxplayer can read nearly all formats.

Step 2: Main Program

The main program is called startloop.py

Basically, il plays all main video in directory /media/USB/videos in a loop

Sensor 1, 2 and 3 will generate interrupts on pin 11, 9, 25 respectively

Everytime a sensor detects an object, a small video is played from directory /media/USB/button

Step 3: Watchdog

Some times, the main video may stop looping for unknown reasons.

A watchdog was build to restart the videoloop service.

The watchdog constantly monitors the cpu consumption of the process omxplayer.bin

If the CPU consumption goes below 10% or above 50% for more than 10 sec, the videoloop service will be restarted

Step 4: Video Files

The main video is stored in a directory called "videos" on the root of an USB key that will be plugged in the raspberry.

The small cartoon are stored in three directories "button1", "button2" and "button3" on the root of the same USB key.

This allows to change the videos easily without changing the RPI program.

Notice that the small cartoons have to be saved as .h264 files.

Attachments

Step 5: All Files Needed

This archive contains all the files needed for the project to work

Attachments

Step 6: Installation

The file install.sh (included in the archive install.zip) will help you install everything...

Step 7: Finalisation

Two more steps are needed :

  • First : modify the file /boot/config.txt the option "gpu_mem" must be set to 128

gpu_mem=128

  • Second : modify the file /boot/cmdline.txt following options worked for me

coherent_pool=6M smsc95xx.turbo_mode=N dwc_otg.lpm_enable=0 console=ttyAMA0,115200 console=tty1 root=/dev/mmcblk0p2 rootfstype=ext4 cgroup_enable=memory elevator=deadline rootwait