On 01 Nov 2007 Klaus Schmidinger <Klaus.Schmidinger@xxxxxxxxxx> wrote:
> I'm looking for a method to convert a JPEG image to an
> MPEG-2 I-frame that can be displayed through VDR's
> cDevice::StillPicture() function. The conversion should
> be done by a (sequence of) shell command(s).
May be something like this:
#!/bin/bash
#
# requires: ...topnm, pnmscale, pnmcomp, ppmntsc, ppmtoy4m, mpeg2enc
#
# video format. pal or ntsc
FORMAT=pal
# target image width/height (taking into account visible screen area)
if [ "$FORMAT" = "ntsc" ]; then
TW=600
TH=420
else
TW=632
TH=512
fi
TMP=/tmp/image_convert.$$.pnm
IMG=$1
MPG=$2
DIR=`dirname "$MPG"`
if [ ! -d "$DIR" ]; then
mkdir -p "$DIR"
fi
#
# get the file type and set the according converter to PNM
#
FILE_TYPE=`file -i -L -b "$IMG" 2>/dev/null | cut -f2 -d/`
case "$FILE_TYPE" in
jpg | jpeg)
TO_PNM=jpegtopnm
;;
tiff)
TO_PNM=tifftopnm
;;
bmp | x-bmp)
TO_PNM=bmptoppm
;;
png | x-png)
TO_PNM=pngtopnm
;;
Netpbm | pnm | x-portable-pixmap)
TO_PNM=cat
;;
gif)
TO_PNM=giftopnm
;;
*)
echo "filetype '$FILE_TYPE' is not supported"
exit 1
;;
esac
#
# 'chroma subsampling mode' mjpegtools >= 1.8.0
#
SUBSAMPLINGMODE=""
if ppmtoy4m -h | egrep -q "'420mpeg2'"; then
SUBSAMPLINGMODE="-S 420mpeg2"
fi
#
# extract the image size & compute scale value
#
LANG=C # get the decimal point right
$TO_PNM "$IMG" >$TMP 2>/dev/null
S=`pnmfile $TMP | awk '{ printf "%d %d ",$4,$6 }'`
S=`echo $S $TW $TH | awk '{ sw=$3/$1; sh=$4/$2; s=(sw<sh)?sw:sh; printf "%.4f\n",(s>1)?1.0:s; }'`
#
# now run the conversion
#
if [ "$FORMAT" = "ntsc" ]; then
pnmscale $S $TMP | \
pnmpad -black -width 704 -height 480 | \
ppmntsc | \
ppmtoy4m -v 0 -n 1 -r -F 30000:1001 $SUBSAMPLINGMODE | \
mpeg2enc -f 7 -T 90 -F 4 -nn -a 2 -v 0 -o "$MPG"
else
pnmscale $S $TMP | \
pnmpad -black -width 704 -height 576 | \
ppmntsc --pal | \
ppmtoy4m -v 0 -n 1 -r -F 25:1 $SUBSAMPLINGMODE | \
mpeg2enc -f 7 -T 90 -F 3 -np -a 2 -v 0 -o "$MPG"
fi
#
# cleanup
#
rm $TMP
--
Stefan Huelswitt
s.huelswitt@xxxxxx | http://www.muempf.de/
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