USAFRet :

Resolution, codec (compression), bitrate, and the capture device matter.

1 minute of 1080 AVI is larger than 1 minute of 1080 mp4.

Solution? Capture exactly 1 minute. Examine the resulting file size, and extrapolate from there.

Even that is not exact.

Exactly 3 minutes of AVI in my dashcam might range from 344MB to 433MB.

1680x960, 15110kbps bitrate, 25 frames/sec = 344MB file size

1680x960, 19590kbps bitrate, 25 frames/sec = 433MB file size

The bitrate difference is whatever the camera thought it should do at that moment.

I know resolution and bitrate matter. I am not sure what you mean by capture device though. However, the entire point has been ignored.

For i am "LOOKING FOR A MATHEMATICAL FORMULA". (Note. The use of capitalization is not an indicator of raising ones voice, my particular usage has always been to use capitalization to make specific important words stand out).

For example: Is this the mathematical formula?

Bitrate X Bit depth X resolution X Frames Per Second X Codec compression ratio = Total number of bits per second

This is an example, it is undoubtedly the wrong formula since i am here asking for it. But to say , or more accurately imply that there is no mathematical formula is to say that mathematicals, does not exist, and by extension you would have to say that computers, WHICH RUN ON MATHEMATICS, cannot exist.

Everything you said may be important. But you missed the entirety of the point. I want the mathematical/empirical/verifiable formula. I do not want anecdotal evidence.

Thankyou for sharing examples though, it appears you are able to understand how bitrate factors into everything, but you still have not shown how you are able to get 344MB from the variables, 1680x960, 15110kbps bitrate, 25 frames/sec, simply giving me the information you can obtain about your device including the variables, without showing how they are included in a mathematical formula is not helpful. I get that it was only an example using your particular device.

However, do you get 344MB by Simply adding all the numbers together? What about times (X) them together to get the number of bits? And then divide by 1,000 to get kilobits? and then divide by another 1,000 to get megabits?

Then what if the AVI format enables the total video to compress by 30%. would you then divide your megabits answer by 1.30???? Would you then have the correct answer in the AVI format???

You can have a mathematical formula, which includes the codec, file format, bitrate, bit depth, resolution, Frames Per Second, However, all i want to know is, What EXACTLY IS the mathematical formula.