” INDEX
Indicates an index (position) within the current FILE. The position is specified in mm:ss:ff (minute-second-frame) format. There are 75 such frames per second of audio. In the context of cue sheets, “frames” refer to CD sectors, despite a different, lower-level structure in CDs also being known as frames.[5] INDEX 01 is required and denotes the start of the track, while INDEX 00 is optional and denotes the pregap. The pregap of Track 1 is used for Hidden Track One Audio (HTOA). Optional higher-numbered indexes (02 through 99) are also allowed.
”
Also you need to know frame rate.
Therefore you need:
user@localhost:/1977-Pat_Metheny-Watercolors> awk '/INDEX/{split($3,t,":"); printf t[1]":"t[2]":%03d\n",t[3]*1000/75;}' *.cue
00:01:000
06:29:946
12:34:986
16:40:000
21:26:733
26:26:266
29:00:000
31:40:000
user@localhost:/1977-Pat_Metheny-Watercolors>
That’s all. ))