Nu Math ? help needed with file sizes

[EricB]

When using DVDx to create mpg2 files, the default maximum file size is 750M. I have used this in the past, and the resulting files were reported by Windows Explorer to be 747M.

I load one of these into the SVCD burning program expecting it to say a 747M file won't fit on the 700M disc, but it does with no problem. OK...

So then I use the same setup to create mpg1 files to burn with Easy CD Creator as a normal data disk (not VCD). Then it reports that the 747M file won't fit on the 700M disk (which makes sense). I try the same file to burn a VCD, and it indicates it will fit!

I'm sure the answer must be simple, but I guess I'm missing the key.

[EricB]

Actually, the default file limit is 730M not 750M, but the question is the same.

Any help?

[neomaine]

Eric,

When formatting a disk for regular files, the file system itself using up space for thing s like defining sectors, file alloc tables and the such. These things are not present (well, to a much lesser extent anyway) on a disc formatted for (S)VCD for a video stream. That is where the 'extra' space comes from/goes to.

That's about as generic as you need to answer your question. If you search the site this question has been asked before with MUCH greater detail.

Have a good one...

[mb1]

VCDs and SVCDs have different sector formats (2.324) than data cd (2.04.

So if you calculate for a 80min-CD-R:
79:59 min = 4799 sec

4799 x 75 x 2324 / 1024 / 1024 = 797,7 MB VCD/SVCD-Format
4799 x 75 x 2048 / 1024 / 1024 = 703 MB Data-Format

You can do that yourself for 74min-CD-R.

Sector-size on CD-R is 2.352 ! The difference to the various formats is filled up with some info like error-correction and so on. As you can see VCD/SVCD has almost no error-correction. That´s why it should be burned with 4x max speed.

Scratch your VCD and it should be almost unplayable und uncopyable because of the lack of error information. Or make a simple finger print on the surface

That´s the story ...

regards
mb1

[EricB]

Thanks mb1, great explanation.