[vdr] How to compute length of a recording?

[Dirk]

Hello,

how do I get the duration in a shell script?
The following code does not always compute the correct value:

sumlen=0
for i in "$recdir"/0*.vdr ; do
    # length in sec. in ID_LENGTH
    ergebnis=$(/usr/local/bin/midentify "$i")
    eval $ergebnis
    sumlen=$(echo "scale=3 ; $sumlen + $ID_LENGTH" | bc)
done
echo $sumlen

(midentify is mplayer -vo null -ao null -frames 0 -identify "$@")

Can you tell me a correct way?

Thank you,



Dirk