scrolltext

#!/bin/bash
#
# scroll text - scrolls text
#   by james w. morris.
#
#   creates a video of text scrolling over moving stripes to
#   give slight parallax effect.
#
#   for demo see: http://youtu.be/_kKpCxgNQyM
#
#------------------------------------

text="The quick brown fox jumped over the lazy dog"

# text properties:
TXTFONT="NewCenturySchlbk-BoldItalic"
TXTSIZE="200"
TXTFILLCOL="orange"
TXTLINECOL="SaddleBrown"
TXTSTROKE="8"

# number of pixels to move text each frame
STEP=4

# output image dimensions:
OW=640
OH=480

# output directory to render frames to:
ODIR="out"

# stripe properties:
STRIPECOL1="CornflowerBlue"
STRIPECOL2="LightSteelBlue4"
STRIPEW=32

# general background colour:
BGCOL="MidnightBlue"

# end of configurable options
#------------------------------------

function image_geometry
{
    IFS= set $(identify -format "%w %h" $1)
    W=$1
    H=$2
}

if [ -d $ODIR ]; then
    echo "Output directory '$ODIR' exists. Abort."
    exit
fi

mkdir -v $ODIR

if [ ! -d $ODIR ]; then
    echo "Failed to create output directory '$ODIR'. Abort."
    exit
fi

convert -pointsize   $TXTSIZE       \
        -font        $TXTFONT       \
        -strokewidth $TXTSTROKE     \
        -stroke      $TXTLINECOL    \
        -fill        $TXTFILLCOL    \
        -background none label:"${text}" \
        \( +clone -shadow 70x8-24+24 \) +swap -composite \
        text.png

image_geometry text.png
TW=$W
TH=$H

# make stripes...
SW=$((STRIPEW*4))
SH=$((TH*4))
SH=$((SH/3))
ASH=$((SH*3))
ASH=$((ASH/4))
SX1=$((STRIPEW*2))
SX2=$((SX1+STRIPEW))
convert -size ${SW}x${SH} xc:none \
        -fill $STRIPECOL1 -draw "rectangle 0,0    $STRIPEW,$ASH" \
        -fill $STRIPECOL2 -draw "rectangle $SX1,0 $SX2,$ASH" \
        \( +clone -background black -shadow 70x10-32+32 \) +swap -composite \
        stripe.png

until [ $SW -gt $TW ]; do
    convert stripe.png stripe.png +append stripe.png
    image_geometry stripe.png
    SW=$W
done

# create background
convert -size "${OW}x${OH}" xc:$BGCOL bg.png

N=0
F=1
S=0
MAX=$((TW+OW))
MAXFRAMES=$((MAX/STEP))
SY=$((OH-SH))
DY=$((SH-TH))
DY=$((DY/2))
TY=$((SY+DY))

until [ $N -gt $MAX ]; do
    echo Processing frame $F of $MAXFRAMES
    OF=$(printf "%s/frame_%06d.jpg" $ODIR $F)
    TX=$((OW-N))
    SX=$((0-S))
    convert bg.png \
        stripe.png -geometry +$SX+$SY -composite \
        text.png   -geometry +$TX+$TY -composite $OF
    N=$((N+STEP))
    F=$((F+1))
    S=$((S+1))
done

ffmpeg  -i "$ODIR/frame_%06d.jpg" -r 30 -vcodec h264 scrolltext.mov