> For the same reason you can't make a perfect copy of an audio CD even if it's > digital media, try to read them several times and compare the result.
Not true, with a good burner (e.g. all the Sony CRX...) you get bit-perfect reads. Same with the one cdrom drive which I also tested. The number of bytes read per audio track is always the same, but the number of null bytes at the start and end varies (more at the start, fewer at the end). The variation is between drives as well as between reads. This will of course stuff your md5s, unless you always strip leading and trailing zeros. The variation is usually/always in multiples of 4 bytes (= 1 sample on each channel). Keeping these zeroes constant is technically impossible. I always write at 16x because then I can still use the computer. Writing at more than 20x actually makes things much slower(!) because of the dozens of buffer underruns, at which the drive always spins down to 1x and then gradually speeds up again. PIII-450 with ATA66 drives. My writer can 48x hahaaa... ROTFL. Those numbers are just BS, of course on a faster box you'd get a bit more than 16x. Those Benq CD-R seem to be ok, never had a coaster, but have only done data disks. THey're also phtalocyanine ones, which supposedly have a better longevity. The sector size on audio is 2352 bytes, on data disks 2048 bytes. The difference goes into error correction. Drives which allow to read all 2352 bytes on data disks allow to check up on how many errors the CD contains. Volker -- Volker Kuhlmann is possibly list0570 with the domain in header http://volker.dnsalias.net/ Please do not CC list postings to me.
