在文本文件中的每4行读取，编辑和写入

Question

long time reader first time asker.

I am working on some vtt (closed caption) files that I need to edit the timestamps for. The format of the file is as follows:

177
00:07:37.450 --> 00:07:39.690
- [Liz] How would you suggest an organization devise

178
00:07:39.690 --> 00:07:41.719
the accountabilities for culture?

179
00:07:41.719 --> 00:07:43.690
- [Tamara] It is a shared accountability  

I have written the following code to read the file, calculate the new timestamps (5% slower) and spit out the new timestamps:

from sys import argv
script, filename = argv

adjustment = input("Adjustment multiplier: ")

video = open(filename, "r+")
lines = video.readlines()

video.seek(0)

for l in lines:
    if l[:2] == "00":
        #here I've omitted a lot of calculations to turn the timestamps 
        #into milliseconds, apply the adjustment multiplier, and turn them back into
        #minutes, seconds, and milliseconds.

        new_line = str(#concatenation of new values into timestamp format)
        video.write(new_line)

video.close()

The calculations work great, but the problem is that it dumps all the new lines into the start of the file instead of writing over each timestamp line and skipping the rest.

I would love to hear what you guys think! I've been wrestling with this for a while and have tried a bunch of things but haven't quite been able to make it work.

Thank you!

Answer 1

You can try enumerate while iterating the lines , and then do the same process:

# Reading code here ...

for index, line in enumerate(lines):
    if index % 4 == 0:
        # Your code here ...

Hopefully it helps :)

Answer 2

Fixed it!

All I had to do was add:

else:
        video.write(l)

to the if-statement. That way, if it matches my parameters the calculations are run and it writes the new line, but if it doesn't, it just writes the old line.

Thanks all!