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Thread: Optical Media (CD-R)'s space issue

  1. #1

    Optical Media (CD-R)'s space issue

    When we write a data CD, we can burn a max. of 700 MB of data. OK.
    But when we create a Video CD (MPEG 1), we can burn a max of 80 MIN video, done.
    After burning, when we open the MPEGAV folder of VCD, the total size of all AVSEQ[x]'s files is 783 MB. (More if 75 MIn of video and pictures are also written (A pic. is displayed for 5 sec in a VCD Player). The limit crosses to as much as 796 MB. How is this possible. I have also tried to copy MPEGAV folder to HDD, is still shows 700+ MB. This 700+ MB of .DAT files cannot be written as a Data CD because a CD+R can have a max data limit of {700 + (2(CDFS))} MB.
    smoking is really bad for ur PC....

  2. #2
    Senior Member
    Join Date
    Oct 2001
    I know that the low-level configuration of a Data CD involves redundancy, probably in the form of CRC checksums. It makes sense because CD's, as we've seen from Audio CD's, get scratched easily and skip. It would be a disaster to execute corrupt program code -- so Data CD's have redundancy somewhere. It could (the redundancy) be what eats up the ~100MB that you're missing. When the OS goes to read data from the CD, the drive itself probably takes care of this very low level stuff so all that needs to be done is to seek & read...

    I'm not sure if Video CD's have this redundancy. But I think most Audio CD's don't have it. Haven't really worked in any depth with the VCD/SVCD formats to know enough about them for this...

    Also, some cd burning programs let you "over-burn" a disc. This means you can write beyond the rated capacity, but some drives don't like (ie, a few drives are rumored to destroy their seek heads or something like that going too far beyond their design) those very outter tracks and some CD media doesn't do a good job storing that extra data. Your mileage would vary if you over-burned your CD media. Also, there are CDs on the (black) market "labeled" for 800MB, but I think they're not "official" because of the extra capacity, and they're probably the same as a 700MB CD except with the TOC / Disc ID area written somewhat differently than normal to be recognized with the extra space, even if can't possibly hold it all... (ie, be a cheap product that possibly corrupts data past ~750MB or some other number)

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