[Scummvm-devel] DOSBOX adlib emu

[yotam barnoy]

If we can get the volume to be decent in Scumm games, I'd like to have
it replace MAME for small targets (maybe other than the DS). Right now
we can either choose MAME with only OPL2, or DOSBOX with OPL3. I'd
like to add a setting of DOSBOX with OPL2.

Yotam


On Thu, Dec 30, 2010 at 8:43 PM, Johannes Schickel <lordhoto at scummvm.org> wrote:
> On 12/30/2010 07:17 PM, yotam barnoy wrote:
>>>
>>> The code size of the MAME emulator should be less than for the DOSBox
>>> emulator, which is why it might be still prefered by backends as the NDS
>>> one. Also we have certain low quality versions of the MAME emulator,
>>> which used to be faster but less precise than the normal MAME one we
>>> use, I am not sure whether they are still faster than the DOSBox
>>> emulator though.
>>
>> OK I'll test the low quality MAME version and see how it measures up
>> performance-wise. The problem is I don't know how to compare the sound
>> quality vs DOSBOX.
>
> Basically you try to compare it against a real OPL2 chip :-P.
>
> Our MAME emulator has its own share of problems though, it isn't really a
> precise emulation of an OPL2 chip. Newer MAME OPL emulators are better in
> that regard but not GPL anymore, thus the DOSBox guys wrote their own
> emulator.
>
> If you are looking for a good case there the MAME emulator is off: The
> "elevator" sound effect of Kallak's Tree House in Kyrandia 1 sounds wrong
> with MAME.
>
>
>>> PROP_OLD_ADLIB isn't related to the AdLib emulator to use though, it's
>>> only related to how some data is interpreted in the MIDI AdLib driver.
>>
>> Still, only Scumm games seem affected. The music in Scumm is VERY
>> soft, almost inaudible. PROP_OLD_ADLIB affects some values in the
>> volume calculation, and I wouldn't be surprised if the problem is that
>> whatever values are used don't work well with the DOSBOX adlib driver.
>
> Well it might be that the volume handling in the DOSBox emulator is
> different to the MAME one (i.e. it produces a different volume level with
> the same audio stream volume settings).
>
> I made a short test and it seems the DOSBox emulator produces lower volume
> levels in general. I checked the DOSBox sources and it seems they setup some
> scaling to the output of the DOSBox emulator, i.e. they double the volume,
> as far as I can tell.
>
> // Johannes
>