MAMEWorld Forums - EmuChat - Re: Question about ALG driver status

> > > OK, let me pose this question in relation to the above: does this mean that MAME
> > > should also emulate the laserdisc players in their entirety for the games that
> used
> > > them? Digitised disc data could be fed to a virtual laser pickup, the VBI decoded
> > > within the LD player virtual machine, and the appropriate frame data fed from the
> > > virtual player's video output to MAME's framebuffer for display.
> >
> > Yes it should. And it should output the composite video so we can decode it in a
> > programmable shader and provide a set of dynamic picture controls like you'd get
> with
> > a real system.
> >
> > > Granted, I am being slightly silly in asking that question, but not entirely.
> Given
> > > that we're talking about reproduction of an analogue medium in a digital format,
> > > we're always going to be stuck with the 'how far do we go' and 'where do we stop'
> > > questions.
> >
> > And people said storing home computer tape software as WAV files and emulating the
> > front-end was silly (rather than just storing bytes), or emulating keyboard MCUs
> and
> > interface chips was silly (rather than just faking it at protocol level), and
> > emulating CPS2 encryption was silly (rather than just using XOR files), or
> requiring
> > encrypted NeoGeo GFX ROM images was silly (rather than using pre-decrypted GFX like
> > NeoRageX), yet here we are.
>
> Permit me another question?
>
> This seems to me to be crossing from emulation to simulation?
>
> The laserdisc is an analogue to a hard drive, so it feels to me like extending this
> means that MAME should simulate the cylinders and head(s) of a hard drive, the IRQ's
> generated, the ISA/PCI bus, memory controller, etc. The laserdisc player isn't really
> that different from the hard drive as it is just the medium that reads out the bytes
> stored on a "Storage platter".
>
> I feel like laserdiscs are being held to a higher standard than hard drives with
> respect to being supported in MAME. Shouldn't the support requirements be the same
> for both mediums?
>
> I completely get why we want to have the laserdisc itself converted into a series of
> bits to represent the physical layout of data on the disc, I'm just wondering why the
> laserdisc player itself isn't emulated?
>
> That requirement for the laserdisc player to be simulated seems to me to be the thing
> preventing laserdisc inclusion in MAME as it seems to me to be setting an impossibly
> high requirement. Though of course, since I've never been involved in MAMEDev
> discussions I could be unaware of other requirements preventing it.

It is a higher standard because it is analogue. We need the best SQNRs that are practical. Even with good design every rip will be quite different and have a different fingerprint. This is because the data is left as is and is not quantized to discrete values. It contains the random variation caused by noise.