For a given bitrate

[~*McoreD*~]

Can anybody please show me how to calculate the filesize of a given audio file's data?
In proper maths...

For Example:

Windows Media Audio 9
128 kbps, 44 kHz, stereo 1-pass CBR
Length: 04:29 (269 seconds)

How can we determine the file size mathemtically? I have got only slight idea on how. I know the know the maths to do it but not how to use the kHz data for it.

So what I did was:

128kb/s * 269s = 34432kb
34432kb / 8b = 4304kB
4304kB / 1024 = 4.203125 MB = 4.2MB

But the actual file size is 4.14MB
Is that right? But I didn't use the fact 44.1kHz Will that affect the file size? Please help..

[RadiationBoy]

hmmm this is an interesting question. here is what I'm thinking



that seems like the logicly correct answere.

and that look like what you did. so I'm guessing that is the correct way.

i mean you only got a slightly diffrent answere, but you probly don't the exact numbers so if they get rounded then you'll get a lil diffrent numbers........maybe lol


eidt:

umm just out of curiostiy why in the hell are you wondering this?? heheheh :P

[~*McoreD*~]

Hi RadiationBoy,

Thanks for the reply...

So I was right then...but I was wondering whether the frequency 44.1KHz (or sometimes 48KHz) won't affect the filesize...

Quote:

umm just out of curiostiy why in the hell are you wondering this?? heheheh

LOL. Honestly, now it is more than a week passed since my post...and now I can't remember why did I ask it...
I think I was doing some audio quality comparisons and suddenly this method was needed to compare or for some reason...

[RadiationBoy]

hmmm thats interesting thought. I think it would have an effect. because.... well i'm not sure LOL. I'll have to look that up. /me goes too google

[Sephiroth]

it should have an effect..... the higher the frequency should mean a higher file size, i don't know how it would fit into the calculation though, for images the way to determine file size is #of pixels times the color depth divided by 8, so if the image was 320 x 240 @ 24 bit color it would be:

320 x 240 = 76800 bytes or 76.8k

24 x 8 (8 bits in a byte) = 3 bytes

76800 x 3 = 230400 bytes or 230.4k

but for audio, i have no idea other than #of seconds times bitrate

[unicorn]

As I'm such a lazy bas**** I have always used aacalc from Audioactive.
Get it and try it (free util) from

/ftp://ftp.telos.cc/audioactive/aacalc.exe

[~*McoreD*~]

Doesn't matter Saphiroth, your knowledge of calculating the size of an image, made me full
Wow, I didn't know that...thanks!

@.unicorn:
An interesting tool, mate
According to it, the frequency doesn't affect the file size I dunno why? But it affects the source filesize...

Anyway, we are investigating a way to find it in proper maths...