Figure out bitrate using math???

Sometimes certain programs dont give out the correct bitrate on mpeg2 videos. So how would one go about finding the bitrate using math?

Ex.....Video is:
37.47 sec
89,899,008 bytes

i dont quite get it..
are you giving us the reason or asking us how to do it?
because i really dont get the EX.....Video you have got there....

I get what you're saying. I think you convert bytes to kilobytes since that's what video bitrates are in. Then divide that by the time of the video. Maybe I'm wrong.

Im asking how you would do it.....I have a short clip that says its 65mbps which is obviously wrong. Using math how does one figure out the bitrate?
Video length is 99 seconds
Video size is 89,899,008 bytes

I know it can be done but its confusing.......

EX= Example :)

Ok heres what i did.....Anyone correct me if im wrong plz.
89899008 bytes = 719.19 megabits
719.19 megabits divided by 99 seconds = ~7.2 megabit per second????

Almost right, 1024 bits in one byte so it's really 736.45 MB.

The 7.2 mbps is the whole movie, if you have audio and video you have more math to do. :D

8bits = 1 byte
Here is the website i use for all my bits and bytes.
http://www.speedguide.net/conversion.php

Forgot about the audio lol So i would have to subtract the audio size. BAH!

8bits = 1 byte So what is 4 bits?

Uhhhh .5 bytes.....Is this some sort of trick question lol

No, it's called a nibble.

Im asking how you would do it.....I have a short clip that says its 65mbps which is obviously wrong. Using math how does one figure out the bitrate?
Video length is 99 seconds
Video size is 89,899,008 bytes

I know it can be done but its confusing.......

EX= Example :)
8bits=1byte
so
89899008 bytes=11237376bits
11237376/99=bits per second
bits per second=113508.84
about 113.508kb per second
not too complicated...but lots of big numbers...

89899008 bytes = 719192064bits
89899008 * 8 =719192064
8bits per 1 byte

Looks like im not the only one not good at math lol

You didn't give me time to answer. :)

No, it's called a nibble.

OH

MY

GOD!!

:mad:

8bits=1byte
so
89899008 bytes=11237376bits
11237376/99=bits per second
bits per second=113508.84
about 113.508kb per second
not too complicated...but lots of big numbers...

That should have read 1024 bytes in 1 kilobyte.

As long as I know what I'm talking about. :D

Almost right, 1024 bits in one byte so it's really 736.45 MB.

The 7.2 mbps is the whole movie, if you have audio and video you have more math to do. :D

what you should really do is this:

(filesize / duration) / 1048576 * 8 = mbps

(89899008 / 99) / 1048576 * 8 = 6.9280303030303030303030303030303 mbps

or 6.93 mbps

Not forgetting that most broadcasts are actually VBR, which is the reason why you get weird values..

If you want to find out the realtime bitrate at any given time, and the file is a .ts file, then use a program called TSReader.

I also find that PowerDVD6 is fairly accurate in reading bittrates (it calculates it every second, which is why some parts will have a higher bittrate than others in a VBR broadcast)

another useful calculation is working out how much you can fit onto a single dvd-r.. you can do that by using this formula:

4489 / (bitrate / 8) = amount of seconds of video you can fit

so for example, using your above video you could fit

4489 / (6.93 / 8) = 5182.11 seconds worth

the more accurate calculation would be starting from the beginning:

4489 / ((89899008 / 99) / 1048576) = 5183.58 seconds

The further back you go in the chain, the more accurate the calculation will be. That is, you need to use bytes and seconds in your calculations and not round up/down whilst you're calculating anything.

(filesize / duration) / 1048576 * 8 = mbps
Such formulas only have meaning if you specify what units to use. Do you have to insert the filesize in MB or maybe Bit or TerraByte? :)

I'll have to quote myself...

That is, you need to use bytes and seconds in your calculations and not round up/down whilst you're calculating anything.

Sorry, I didn't see that. It was too far away from the corresponding formula... :)

oops,,I just bit myself trying to read this post :D

Man, it's so simple! Just take the bitrate b and the runtime r, the processorspeed s and the RAM size x.
Then do b/r*s^x+m^2c^4+c^2p^2, each a function of the place and the time in 4-dimensional space-time. This equals a differential equation which we abbreviate H Psi(x,t) = E Psi(x,t). This equation is invariant to Lorenz transformations making it easy to compute. The information you search for is the eigenvalue of the hermitian operator H.
Now, was it really that difficult?!!

Edit: I'm just learning for an exam in quantum mechanics... :)