Add video processing

prepareVideo.sh

@@ -0,0 +1,21 @@
+#!/bin/bash
+
+# The video starts with a few blank frames, we want to know when the stop
+ffprobe -f lavfi -i "movie=app.mp4,blackdetect[out0]" -show_entries tags=lavfi.black_start,lavfi.black_end -of default=nw=1 -v quiet > ffmpeg_info
+END_OF_BLACK=`cat ffmpeg_info | grep end | head -n1 | cut -d'=' -f2`
+
+# Find crop values for black bars
+CROP=`ffmpeg -i app.mp4 -t 1 -vf cropdetect -f null - 2>&1 | awk '/crop/ { print $NF }' | head -n1`
+
+# Crop and trim black frames at start
+ffmpeg -ss $END_ONF_BLACK -i app.mp4 -vf "$CROP" app2.mp4
+mv app2.mp4 app.mp4
+
+# Generate gif palette
+ffmpeg -y -i app.mp4 -vf fps=10,scale=720:-1:flags=lanczos,palettegen palette.png
+
+# Create gif
+ffmpeg -i app.mp4 -i palette.png -filter_complex "fps=10,scale=720:-1:flags=lanczos[x];[x][1:v]paletteuse" app.gif
+
+# Clean up
+rm ffmpeg_info palette.png