How to delete lines after first checking next 3 lines - awk

Question

I have a text file similar to this
00:00:24.752
8,594
3,847
0
00:00:25.228
0
1,692
0
00:00:25.738
6,548
5,304
0
00:00:26.248
1,807
417
0
00:00:26.758
3,913
5,335
0
00:00:26.792
0
00:00:27.234
0
00:00:27.268
0
0
0
00:00:27.778
9,903
2,345
0
00:00:27.812
0
00:00:28.322
0
9,501
0
this is network traffic and the first part is a timestamp while the next two are sent and received traffic. The third is a zero which i do not know why is there.
So my goal is to keep only the lines that have at least a value of sent/receive traffic and also delete the third 0 every time. So i will have a result like this.
00:00:24.752
8,594
3,847
00:00:25.228
0
1,692
00:00:25.738
6,548
5,304
00:00:26.248
1,807
417
00:00:26.758
3,913
5,335
00:00:27.778
9,903
2,345
00:00:28.322
0
9,501
Have tried using awk in the sense of checking the length of the current line and if the line is less than 8 characters then print that line and the next 2. But since the file is not always having at least 2 values after the timestamp it is not working properly.

Answer 1

awk '
/[0-9]{2}:[0-9]{2}:[0-9]{2}\.[0-9]{3}/ {
if (NR > 1) p()
i = 0
}
{ buf[++i] = $0 }
END { p() }
function p() {
if (buf[2] || buf[3]) {
print buf[1]
print buf[2]
print buf[3]
}
delete buf
}' file
p is a function that prints buffered lines if 2nd and 3rd of them are not empty or zero, and clears the buffer. It is called whenever a timestamp is seen (and it's not the first line in the file) and when EOF is hit. So the script above basically buffers lines between two timestamps, and if they meet the criteria that there should be at least two lines after timestamp, and they shouldn't be zero, prints them.

Answer 2

This might work for you (GNU sed):
sed '/:/!{H;$!d};x;/\n.*\n.*\n/{/\n0\n0\n0/!s/\n0$//p};x;h;d' file
If the current line is not a time stamp (does not contain a :), append it to the hold space and if it is not the last line, delete it.
If the current line is either the last line or a time stamp, swap to the hold space and check that the previous record contains 4 lines and that the last 3 lines are not zeroed, if so remove the last line of the record and print the amended record.
Swap back to the pattern space, replace the hold space by the current line (time stamp) and delete it.
N.B. When a line is deleted no further sed processing takes place for the current line.

Answer 3

If you want to omit all 4th lines, this the awk script to achieve this:
awk 'RN % 4{print}' input.txt
Results with your desired output.