Simple SRT subtitle time shift with awk.

Call me an one-line awk command freak. (sorry, it only processes integer seconds.)

awk -v shiftsec=2 '{\
    if(/:..:.*:..:/){\
        split($1,s1,","); split($3,s2,",");\
        split(s1[1],s1t,":"); split(s2[1],s2t,":");\
        time1=((s1t[1]*60+s1t[2])*60+s1t[3])+shiftsec;\
        time2=((s2t[1]*60+s2t[2])*60+s2t[3])+shiftsec;\
        ss1=time1%60;mm1=((time1-ss1)/60)%60;hh1=(time1-ss1-mm1*60)/60/60;\
        ss2=time2%60;mm2=((time2-ss2)/60)%60;hh2=(time2-ss2-mm2*60)/60/60;\
        printf("%02d:%02d:%02d,%03d --> %02d:%02d:%02d,%03d\n",\
               hh1,mm1,ss1,s1[2],hh2,mm2,ss2,s2[2]);\
      }else{\
        print $0\
      }\
    }' oldsrtfile.srt > newsrtfile.srt

I sorta wish I had used shell script at the beginning.