#!/bin/sh
# screens.sh: v46 2007/09/30 KELEMEN Peter <fuji@xfs.hu>
# Generate screencaps for a given videostream in the background.

# Copyright 2007 KELEMEN Peter
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#     http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.

debug () {
	if [ -n "$DEBUG" ]; then
		echo "$@"
	fi
}

set -a

SELF=${0##*/}
VERSION=$( sed -nr '2{s/^[^:]+: ([^ ]+) .*$/\1/p;q}' $0 )
debug $VERSION

W=1280	# destination image width
H=1024	# destination image height

SW=200	# scaled width (one tile in screens)

SKIP=17 # skip how many seconds at beginning of video

START=1	# border size (around tiles) in pixels
DELTA=1	# gap size (between tiles) in pixels

SCREENSDIR=Screens

if [ -z "$1" ]; then
	echo "Usage: $SELF [-slow] <videofile>"
	exit 127
fi

MPLAYEROPTS="-benchmark"

LOOP=1
while [ $LOOP != 0 ]; do
	case $1 in
		-slow)
			debug "option -slow seen"
			shift;
			MPLAYEROPTS=""
			;;
		--)
			debug "option -- seen"
			shift;
			LOOP=0;
			;;
		*)
			LOOP=0;
			;;
	esac
done

if [ ! -r "$1" ]; then
	echo "E: $1 is not readable."
	exit 126
fi

FULLPATH=$( readlink -f $1 )
BASENAME=${FULLPATH##*/}
DIRNAME=${FULLPATH%/*}
if [ -z "$DIRNAME" ]; then
	DIRNAME=.
fi
FILENAME=${BASENAME%.*}
FILEEXT=${BASENAME##*.}


TEMPLATE="${SELF}.XXXXXXXXX"
TEMPFILE=$( mktemp -p "$DIRNAME" $TEMPLATE )
ERROR=$?
if [ $ERROR != 0 ]; then
	echo "E: Error creating temporary file $TEMPFILE ($ERROR), aborting."
	exit $ERROR
fi
WORKDIR=${TEMPFILE}.$$
mkdir $WORKDIR
ERROR=$?
if [ $ERROR != 0 ]; then
	echo "E: Error creating working directory $WORKDIR ($ERROR), aborting."
	echo $ERROR
fi

debug "WORKDIR=$WORKDIR"
cd $WORKDIR

# attempt to identify video stream
mplayer -frames 1 -ao null -vo null -identify "$FULLPATH" 2>/dev/null | sed -nr 's/^(ID_[^=]+)=(.*)$/\1="\2"/p' > $TEMPFILE
ERROR=$?
. $TEMPFILE

debug "TEMPFILE=$TEMPFILE"
if [ -z "$ID_LENGTH" ]; then
	echo "Ooops, couldn't -identify $FULLPATH ($ERROR)"
	exit 125
fi

# scaled height (one tile in screens)
SH=$(($SW*$ID_VIDEO_HEIGHT/$ID_VIDEO_WIDTH))
debug "original: ${ID_VIDEO_WIDTH}x${ID_VIDEO_HEIGHT}"
debug "  scaled: ${SW}x${SH}"
debug "     WxH: ${W}x${H}"

XTILES=$(( $W/$SW ))	# how many screens per column
YTILES=$(( $H/$SH ))	# how many screens per row

# if tiles+gaps+borders are larger than target width,
# take one column away
if [ $(( $SW * $XTILES + ($XTILES-1)*$DELTA + 2*$START)) -gt $W ]; then
	XTILES=$(( $XTILES-1 ))
	debug "too wide, columns set to $XTILES"
fi
# if tiles+gaps+borders are higher than target height,
# take one row away
if [ $(( $SH * $YTILES + ($YTILES-1)*$DELTA + 2*$START)) -gt $H ]; then
	YTILES=$(( $YTILES-1 ))
	debug "too high, rows set to $YTILES"
fi
NUMTILES=$(( $XTILES * $YTILES ))
debug "   tiles: ${XTILES}x${YTILES} (=${NUMTILES})"

FPS=${ID_VIDEO_FPS%.*}
LENGTH=${ID_LENGTH%.*}
FRAMES=$(( $FPS * ($LENGTH-$SKIP) ))
FRAMESTEP=$(( $FRAMES / $NUMTILES ))

if [ $FRAMESTEP -lt $FPS ]; then
	echo "ABORT: FRAMESTEP < FPS! ($FRAMESTEP < $FPS)"
	exit 100
fi
if [ $XTILES -lt 2 -o $YTILES -lt 2 ]; then
	echo "ABORT: too big tiles or too small target"
	exit 100
fi

MPLAYEROPTS="$MPLAYEROPTS -quiet -nosound -vo jpeg -ss $SKIP -vf framestep=${FRAMESTEP},scale=${SW}:-3,tile=${XTILES}:${YTILES}:-1:${START}:${DELTA}"
CMD="nice -n 19 mplayer $MPLAYEROPTS"
debug $CMD
if [ -z "$DRYRUN" ]; then
	if [ -z "$DEBUG" ]; then
		$CMD "$FULLPATH" >/dev/null 2>&1
	else
		$CMD "$FULLPATH"
	fi
	mkdir -p "${DIRNAME}/${SCREENSDIR}"
	mv 0*1.jpg "$DIRNAME/$SCREENSDIR/$FILENAME.jpg"
	rm -f $TEMPFILE
	rm -rf $WORKDIR
fi

cd $OLDPWD

# vim: set tw=0 nowrap number:
# End of file.