Calculating elapsed time

Hello,

I am redacting sections of video clips, and I would like to determine the total length of time of the redactions. The videos can be anywhere from a few seconds to a few hours.

Here is an example of what I need:
I have a video with a length of 14:36. The video starts at 00:00. At 01:25, I will be removing audio from the clip, and at 04:40 the audio will resume. Then again at 08:12 I will remove audio and have it resume at 09:18. I need to calculate the total length of time that the audio was removed.

Column D is the total length of the video
Column E is the time that the redaction starts (01:25 using the above example-----one minute, 40 seconds into the video)
Column F is the time the redaction ends and the audio resumes (04:40 using the above example------four minutes, forty seconds into the video)
Column G is the total length of the redaction (03:15 would be the total length----three minutes, 15 seconds)
A single redaction would appear on one row then any subsequent redactions will appear on the next rows

I need the know how to format the numbers for columns D:G, and I need to know the calculation for Column G (Total Length) as well as the SUM of all redactions for that specific video (which will appear in a separate row).

Using the above example, it could be as simple as 440-125. The problem comes when the Start Time is, for example, 51:10 and the Ending Time is 01:18:20. I can't use a simple SUM function to get the proper result.

Any assistance provided would be greatly appreciated.

If you format it as a time (e.g. 0:51:10 AM and 01:18:20 AM) you should be able to simply sum them up

For example:
Example Snip.PNG

Can you be more specific with the format as time part since there are many options. Thanks!

And just to point out, my desire is to record the times in the columns as 0125, 0440, etc. When formatted as time, it converts 0125 to "5/4/1900 12:00:00 AM" and shows "00:00 AM" in the field where I typed.

Formatted as [h]:mm:ss it works, but it would be great if I didn't have to always type it as a 6-digit number and/or have to type the :

Here's one idea. If you are typing the times in as either 3 digits (m + ss), 4 digits (mm + ss), or 5 digits (h + mm + ss), this will format the cells to hh:mm:ss. This will require a helper column, but from the helper column you could sum these values.
=IF(LEN(M5)=3,"0:0"&LEFT(M5,1)&":"&RIGHT(M5,2),IF(LEN(M5)=4,"0:"&LEFT(M5,2)&":"&RIGHT(M5,2), LEFT(M5,1) & ":"& MID(M5,2,2)&":"&RIGHT(M5,2)))

EDIT: this uses cell M5 as a reference (you will have to change that to whatever column/cell you desire)

For speed purposes, I would definitely prefer to input the times as 3, 4, 5, etc digits (without having to type the ":").

I figured out the format for entering the numbers. It is 00\:00\:00. Then I can just use a simple B-A=C to calculate the difference.