#!/bin/bash
#
# Calin-Andrei Burloiu, 2010, calin.burloiu@gmail.com
#
# This script extracts a thumbnail from a random frame of a video file.
# 
#

if test $# -ne 3; then
    echo "Usage: $0 input-video output-image resolution"
    exit 1
fi

IN="$1"
OUT="$2"
RESOLUTION="$3"
FFMPEG=/usr/bin/ffmpeg

if test ! -f "$IN"; then
    echo "Error: No such file $IN"
    exit 1
fi

# Choose a random frame
DURATION=$(mediainfo --Inform="General;%Duration%" "$IN" | cut -d"." -f1)
SEEK_POINT=$(($DURATION * $RANDOM / 32767 / 1000))

"$FFMPEG" -i "$IN" -ss "$SEEK_POINT" -vframes 1 -s "$RESOLUTION" -f image2 "$OUT"