[paranoia] cdparanoia: non-repeatable incorrectable sectors

[Monty]

> Having recently developed an interest in MP3 and having my own
> CDs on my HD, I looked into cdparanoia.  While I very much
> like the correcting capabilities in cdparanoia III alpha 9,
> to my dismay my CDrom decided that it would like to pop up some
> 'V's every now and then, but not consistently.
> 
> Switching from ide-cdrom to ide-scsi seems to have helped and
> not restricting the default read size (it seems my 2.2.13 does
> not dislike large DMA settings) in interface/scsi_interface.c
> and increasing MAX_RETRIES to 64 in interface/low_interface.h
> did seem to help too.  Unluckily, I still got non-repeatable
> errors, even when setting cdparanoia to realtime scheduling.

Realtime scheduling shouldn't affect anything... that's the whole point of
cdparanoia ;-)

> As this works (and seems to produce error-free rips) I consider
> it a shortcoming (or even bug) of cdparanoia ...

Shortcoming. The CDROM drive is, of course, trying to do it's own alignment
fixes (but can't do as careful a job due to firmware limitations), but it's
getting gummed up and needs to be cleared... the equivalent of clearing a laser
printer paper jam :-)  ATAPI has no command for resetting/clearing out the
drive and the way to wipe the drive clean is different for different drives.
Some you need to power cycle, some you need to eject and re-insert, some you
just need to spin down, etc....

But it's true that I should be exerting a bit more effort on this... spinning
down the drive before giving up at very least.

(It's generally not difficult to find somethignt hat works on one drive.  The
difficulty is not using the new sledgehammer to break all the other drives :-(
CDROM drives are such a hack...)

> I am no good as a C programmer, so I'd be of little
>help patching cdparanoia itself.

Well, it doesn't hurt to brainstorm about tactics for dealing with the paper 
jams.

>                CDROM sensed: LITEON CD-ROM LTN382 WL2A 

Oh dear.

> [2] currently only "[skip]".  Are any other condition (apart
>     from scratch) able to produce audible defects?

Yes, '!'; it literally means that it's statistically likely that errors are 
getting through.

> [5] Even tracks that were not 'corrected' by my scripts (and
>     had no [skip]) can produce differences ... but not due
>     to mis-alignment at the beginning, it seems.  Maybe check
>     it later.

This can happen during periods of silence (no landmarks to use for
verification) or if '!' is popping up.  Do you have examples?  I have ideas for
improving the '!' handling....

Monty

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