by klaymen on Mon Apr 14, 2003 4:30 am
Hi all,
Karr, it seems you're programmer of this great tool? Maybe I could ask you a few internal things that I'm wondering for some time... I must note that I'm only using KProbe for DVD-R/-RW testing so far.
My main question is the exact meaning of PI... is it the PI-detected errors that occur in just one sector, or is it the summed up PI errors of 8 subsequent sectors (otherwise called "PI sum 8")? I'm asking because the standard requests "PI sum 8" to be below 280. Also I'm wondering if PO is the same number otherwise called PIF (PI failures), the number of PI-detected errors that PI could not correct and will undergo PO correction.
Also I noticed, by saving the output as a csv file, that not all sectors seem to be sampled. I interpret the first number of each line as LBA, the second as PI and the third as PO. At the beginning of a media, about one out of 75 LBAs are measured (the LBA differences are around 75), towards the end of the disc the differences climb up to about 150, probably due to faster linear speed in the outer regions. Am I right in the assumption that due to the DVD speed KProbe can only measure the error rates of certain discrete sectors? If so, this would mean the error rate indeed relates to only one particular sector, and not "PI sum 8"? I didn't have the impression I get more samples at a lower speed, but didn't throughly check that...
If my assumptions are right, is there any way to measure every single sector (I know this would take a long time)? I wrote a Perl script that calculates a "pseudo PIsum8" by summing up the error rates of 8 subsequent sampled sectors (which of course are not subsequent on the disc, but spread over about 800 sectors) - but I have no idea if such a plot has any significance.
Last but not least I'm wondering if the LiteOn drives actually deliver the raw data of a sector (including checksums) to the PC, so KProbe itself verifies the checksums, or if the LiteOn drives just deliver the number of PI/PO errors it detected directly to the software. I know this is not really relevant for us users, but I do still wonder.
Thanks a lot, and sorry if I might have messed up some points (I'm no expert in the area of DVD error checking...)
Klaymen