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In Reply to: RE: I doubt seriously if you are right, but let's just leave the matter there. nt posted by cfmsp on September 7, 2011 at 10:36:54:
"What do you see as the possible effects of timing variations of the rip process, other than fragmentation?"
If the data is made available to the OS to be written into a file then the location chosen may depend on the timing, e.g. if there are other files being written at the time. If one is curious one can investigate the LBNs (logical block numbers) assigned by file by using disk level tools that access the file system metadata. However, even these tools will not necessarily show precisely where on the physical disk (cylinder, head, sector) the data is stored because disk drives perform a certain amount of re-vectoring of bad sectors. There are disk diagnostic tools that my help here, but I can't comment about these, as I have no experience with them.
However, in addition to where (sector) data is stored the actual location of the bits themselves (the magnetic patterns) depends on an interaction between application software, operating system software, drive firmware and the timing of disk rotation. The details of this operation will be proprietary to the individual disk drive, but it may be that there are different modes of writing (single sector, multiple chained sectors) and these have different timing due to second order hardware interactions. In addition, the drive write circuitry has to time the start of writing off of data read from the disk and the timing of this will be affected by noise. In extreme cases a read error at the critical time may cause data to be written in an incorrect place, causing data corruption, but I wouldn't expect this to happen with modern disk drives. (This did happen once many decades ago and was a mysterious problem that took months to diagnose and cure as it involved a combination of drive hardware, controller hardware and operating system software. I was on the periphery of this investigation but was familiar with it in some details as I had originally proposed that the disk controller have a number of performance optimizations that improved system throughput, but also made operation flaky on certain lots of disks because of an interaction between controller design and the encoding structure of data on the disk.)
Apart from gross changes such as fragmentation or soft read errors, it's hard to imagine how location will affect the sound out of a DAC, but I wouldn't say this is impossible. That's why I suggested recopying the data and comparing the copies. Of course any of these low level changes in the computer system should have no affect whatsoever on a properly designed outboard DAC. Unfortunately, most DAC designers won't accept responsibility for this situation and those that do throw up their hands and don't know what to do about it. Hopefully this will change and then this discussion will become academic.
Tony Lauck
"Diversity is the law of nature; no two entities in this universe are uniform." - P.R. Sarkar
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Follow Ups
- RE: I doubt seriously if you are right, but let's just leave the matter there. nt - Tony Lauck 11:03:17 09/07/11 (0)
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