opaqueice Wrote: > Also in my own CD ripping I often get perfect rips at 5x speeds or so - > so again, no uncorrectable errors. Of course I don't know how many > correctable errors there were, so it's hard to compare. C1 errors happen continuously and are to be expected. I've just measured a fairly new CD and it had an average rate of 9.7, with a peak of 43. That was reading it at high speed (24x). Re-reading at 4x speed (the lowest that Plextools will do this test), the rate dropped to an average of 4.8 and a peak of 32. One might expect that an audio CD player, reading as it does at single speed, will achieve slightly lower rates than that. Call it 4 per second, and over the course of a 1 hour CD that's about 14,000 corrected C1 errors. Some discs, of course, have far higher error rates, but they still produce a bit-perfect output after error correction.
If there are more than 2 bad symbols in a data block, the error is uncorrectable at the C1 stage, and the data block is then passed to the C2 stage. You quite often find that for CDs in good condition, there are no such uncorrectable C1 errors, and hence the C2 error count is zero. (This was the case with the CD I just measured). Once the data block gets to the C2 stage, an uncorrectble error happens (and becomes a "CU error") when there are 3 or more bad symbols in the data block. My understanding is that in theory (given the amount of redundant data on the CD) it should be possible to correct up to 4 bad symbols, but not all CD players/CD drives implement the full scheme. Perhaps differences in drives' abilities here might go some way to explaining the difference in CU error rates that Phil and I are observing. -- cliveb ------------------------------------------------------------------------ cliveb's Profile: http://forums.slimdevices.com/member.php?userid=348 View this thread: http://forums.slimdevices.com/showthread.php?t=24957 _______________________________________________ audiophiles mailing list [email protected] http://lists.slimdevices.com/lists/listinfo/audiophiles
