cdparanoia, sector offset and last track

[Paul C. Bryan]

Dear fellow users and Monty, o admired king of cdparanoia:

I've dug into the code a bit, and I *think* the way cdparanoia works is
it will not try to read past what it thinks is the last sector of the
last track. If you set a positive sector offset, this would mean it pads
the last track with zeroes. Am I correct?

Paul

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[xiphmont]

On Thu, Feb 5, 2009 at 7:50 PM, Paul C. Bryan <email@...> wrote:
> Dear fellow users and Monty, o admired king of cdparanoia:
>
> I've dug into the code a bit, and I *think* the way cdparanoia works is
> it will not try to read past what it thinks is the last sector of the
> last track. If you set a positive sector offset, this would mean it pads
> the last track with zeroes. Am I correct?

Actually, passing an offset (with -t or -O) is supposed to be handled
as a case of 'the drive is reporting boundaries incorrectly'.  The
information returned by the TOC query is adjusted by the provided
offset, so reads are done as if the CDROM drive had reported a table
of contents with the adjusted offsets.  The hardware may balk at this,
of course...

Monty
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[Paul C. Bryan]

So the "end" flag isn't set until the last (corrected) sector has been
read?

-----Original Message-----
From: xiphmont@...
To: Paul C. Bryan <email@...>
Cc: paranoia@...
Subject: Re: [Paranoia] cdparanoia, sector offset and last track
Date: Fri, 6 Feb 2009 13:23:35 -0500

On Thu, Feb 5, 2009 at 7:50 PM, Paul C. Bryan <email@...> wrote:
> Dear fellow users and Monty, o admired king of cdparanoia:
>
> I've dug into the code a bit, and I *think* the way cdparanoia works is
> it will not try to read past what it thinks is the last sector of the
> last track. If you set a positive sector offset, this would mean it pads
> the last track with zeroes. Am I correct?

Actually, passing an offset (with -t or -O) is supposed to be handled
as a case of 'the drive is reporting boundaries incorrectly'.  The
information returned by the TOC query is adjusted by the provided
offset, so reads are done as if the CDROM drive had reported a table
of contents with the adjusted offsets.  The hardware may balk at this,
of course...

Monty

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Paranoia mailing list
Paranoia@...
http://lists.xiph.org/mailman/listinfo/paranoia

[xiphmont]

On Fri, Feb 6, 2009 at 1:41 PM, Paul C. Bryan <email@...> wrote:
> So the "end" flag isn't set until the last (corrected) sector has been
> read?

I'm not sure what you mean by the 'end flag'.  The :^D in the status line?

Oh, BTW, if the sector offset causes reads past the end of the
physical session and this generates read errors, the code will
eventually force a skip and fill in areas it couldn't read with
zeros.... so it is in fact possible that the end of the disc could be
'padded' with zeros when a positive offset is used... but this is more
of a last-ditch strategy for dealing with an unreadable area than it
is intentional padding.

Monty
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Paranoia@...
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[Paul C. Bryan]

Okay, thanks this makes sense. The end flag I was referring to was the
i_end_case function in paranoia.c.

-----Original Message-----
From: xiphmont@...
To: Paul C. Bryan <email@...>
Cc: paranoia@...
Subject: Re: [Paranoia] cdparanoia, sector offset and last track
Date: Fri, 6 Feb 2009 13:56:36 -0500

On Fri, Feb 6, 2009 at 1:41 PM, Paul C. Bryan <email@...> wrote:
> So the "end" flag isn't set until the last (corrected) sector has been
> read?

I'm not sure what you mean by the 'end flag'.  The :^D in the status line?

Oh, BTW, if the sector offset causes reads past the end of the
physical session and this generates read errors, the code will
eventually force a skip and fill in areas it couldn't read with
zeros.... so it is in fact possible that the end of the disc could be
'padded' with zeros when a positive offset is used... but this is more
of a last-ditch strategy for dealing with an unreadable area than it
is intentional padding.

Monty

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Paranoia mailing list
Paranoia@...
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