Calculator - looking for the formulas for my own app.

[vhelp]

Evening all,

I have another question, but this time, on the Calculators flooting around this site.

went over to the "http://www.vcdhelp.com/calc.htm" site and saw a rather user friendly and simple calc.

Ok, could somebody give me the formulas that I can incorporate in an app that I am thinking about making (for myself) (not another one for this site ). Basically, the the above site is showing, also noticed it has an additional box for SVCD and an advanced mode.

Anyone??
Thanks!!!

PS: I use Delphi 6

[Vejita-sama]

It's pretty simple. A 80min CDR will hold 800B of MPEG data and a 74min CDR will hold 740MB of data. The encoders use bits instead of bytes. 8bits=1byte.

80min CDR = 800,000kbytes = 6,400,00kbits

that's for both video and audio. So based on to convert to min divide by 60, and you get 10666.6kbits * min /sec

Divide by number of minutes of movie to get kbit/sec.

Example: 50min video = 106666/50 = 2133kbits/sec
at audio=224kbits/sec
2133 - 224 = 1909kbits/sec for the video.

[vhelp]

vejita-sama,

Sorry, but your calculation's not working for me (using a spreadsheet to work out the numbers).
I'm lost at your first paragraph. 800B. What's 800B?? ("...800 bytes??&quot...
or did you mean 800MB. Ok, 74min=740mb (makes sense).

Ok, now, 80min cdr=800,000kbytes. Where did you get the 800,000kbytes (6,400,00kbts) from? I'm trying to use the 800,000 or 6,400,00kbts (sound confusing). Are commas out of place? Anyway, I can't seem to get this to work in my spreadsheet! I thought that
800,000kbytes / 8 = 100,000kbits ??

Any suggesions?


(/60) kbts:

[vitualis]

Unfortunately, units are stuffed up in computing...

8 bits = 1 byte
1024 bytes = 1 kilobyte (kb)
1024 kb = 1 megabyte (Mb)
1024 Mb = 1 gigabyte (Gb)

When we talk about kilobits per second (for bitrates), the kilo is the SI kilo.

1000 bits = 1 kilobit

Now:
size = time x bitrate

This is the basic formula. The trick is to get all the units coversions correctly.

Say I have 730 Mb capacity, and I want to fit 40 minutes of video. What bitrate should I use?

bitrate = 730Mb / 40 min
= 18.25 Mb/min
~ 0.304 Mb /s (60 sec = 1 min)
~ 311.5 Kb/s (1024 Kb = 1 Mb)
~ 319,000 bytes/s (1024 bytes = 1 Kb)
~ 2,550,000 bit/s (8 bit = 1 byte)
~ 2,550 kbit/s (1000 bit = 1 kilobit)

Remember the kilo in kilobit is different from the kilo in kilobyte.

Now, if we subtract the bitrate needed for the audio (e.g., 224 kbit/s), then we will need to use a bitrate of ~2328 kbit/sec.

Now this is an oversimplification as there are somthings included above just the video and audio. Thus, this over-estimates the bitrate you can use.

Regards.

_________________
Michael Tam

<font size=-1>[ This Message was edited by: vitualis on 2001-08-18 20:25:54 ]</font>

[vhelp]

Good morning vitualis and vejita, (and others)

Thanks for your responses. I will give both your answers some working on.
See, what I'm after is something like, i.e.,
* to find out how many CDs are required:
* to find out how many kbts:
* etc., etc. I'm looking for different scenarios pending
on my inputs. if that makes any sense (I just woke up, and
I still have the sand man in my yes).
If and when I do create this app, I want it to be simple,
small and compact. Just something that I can have laying
around or floating on my desktop somewhere - I have some
good ideas for my homemade calc. Oh, in my last post about
the calc being just for me, I didn't mean to say that I
don't want vcdhelp to have a copy, but that they probably
have enough of them, hence ...not another one! I don't think that people would want to see another one, would
then?? Well, if I should need help, I may ask more
questions on the formula stuff - may need to end up
uploading a copy for debuging. Maybe! Anyway. . .

On another note. I've ben having a great deal of trouble
with TMPGEnc (a number of versions). It's ben constantly
crashing on me throughout lastnight. And in causing
some instances, causing me to shut down my system.

On another note (one more), I have posted many times at
this great site (though many not responded to), and I realize there's a number of typos. Please don't think I can't spell. (yes, I'm lazy at times to run a spell
check - usually in a rush and can't think straight most of
the time), but I found out that it's not always me. There
seems to be something wrong with my keyboard or via chipset settings or something, becaues when I type fast, sometimes
the char. don't get displayed on the screen. Actually, I noticed this from day one, after repla-cing my motherboard and cpu back in march (i think).

Well, thanks all for the responses - really appreciated.

<font size=-1>[ This Message was edited by: vhelp on 2001-08-19 08:09:26 ]</font>