Re: [Libcdio-help] reading the whole 2352 bytes from every type of sector

[Matheus Izvekov]

On Tue, Mar 4, 2008 at 7:42 AM, R. Bernstein <address@hidden> wrote:
> Matheus Izvekov writes:
>   > On Tue, Mar 4, 2008 at 1:16 AM, R. Bernstein <address@hidden> wrote:
>   > > Sorry, but I'm not sure I understand the lingo you are using and
>   > >  what you want to do. Probably libcdio doesn't do what you want, but
>   > >  there may be code that does something similar to what you want.
>   >
>   > The problem I'm having can be reproduced in the utility cd-read.
>   > Try reading a data sector using -m audio. I can't get the whole 2352 bytes
>   > of the sector this way.
>
>  Not all CD-ROMs and libcdio drivers will allow one to even read a
>  track as an audio sector if that track isn't listed in the TOC as
>  being an audio or red-book track. On the other hand, obviously, some
>  do. Bit if this doesn't do what you imagine, this should not be
>  surprising.

Well to simplify things, imagine i want to implement a cdrom drive
emulator, like daemon-tools, using libcdio.
Do you see the issues now? What I am doing is just implementing the
playstation cdrom drive. Some times the user
(a game for example, not the guy on the control pad) will issue a
command to read the whole 2352 bytes of a sector,
and the real psx just accepts and does that correctly, no matter what
kind of sector it is.

>
>   > Then I use mmc_read_cd to do that, but then this
>   > doesnt work on image files.
>
>  The mmc_* routines issue multimedia commands to a CD-ROM drive. Some
>  support for simulating CD-ROM behavior is tolerated but there is only
>  so far one can go pretending an image file is a CD-ROM. With some
>  effort, possibly one can jimmy up routines to always return false if
>  you ask if the media has been changed, but what does it mean to
>  "eject" a CD image file? (I think here libcdio returns a status like
>  "not supported")

It seems like a good compromise, although I dont see a dilemma here.
For the operations that dont make sense, just dont implement them like you said.
And for a CD image file, almost everything makes sense, except maybe
in case of libcdio eject itself.
For an example of this take a look at daemon-tools. And they even
implement ejecting....

>
>   >
>   > The weird thing is that doing the same thing on a image file, 
> cddio_read_sector
>   > doesnt return an error, but gives some garbage instead.
>
>  Perhaps an error should be returned. The weird thing to me is that you
>  seem to want to just try any a read of a sector in audio format,
>  whether it makes sense or not. There is a saying: garbage in, garbage
>  out.
>
>
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