[vlc-devel] [PATCH V2 1/8] aout: add exclusive argument in plugins start cb

[Rémi Denis-Courmont]

Le keskiviikkona 20. marraskuuta 2019, 12.11.18 EET Thomas Guillem a écrit :
> > Again, I don't think audiophiles care about exclusive mode per se. They
> > want bit exact mode. Exclusive mode is not required (in general), and
> > never sufficient for bit exact mode.
> 
> After reading some audiophile forums, it seems users want either WASAPI
> exclusive or ASIO on Windows, and hog mode on macOS. So for me, they seem
> to care about exclusive (or ASIO).

I've seen people asking for ASIO for ASIO plugins, people asking for bit 
exact, and people confusing their goal - lossless PCM pass-through - with a 
mean - WASAPI exclusive mode or ASIO.

The points are:

1) WASAPI exclusive mode is a WASAPI thing. It means nothing to the VLC core, 
or to most or all other audio output plugins.

2) Even though some people explicitly sought WASAPI exclusive mode, they will 
not be satisfied with it, if what they really want is lossless PCM pass-through 
(a.k.a. "bit exact").

3) ASIO is sought (also) for other reasons, that can only be solved with ASIO 
support - with its assorted IP issues.

> > > I really prefer keeping this name: exclusive since it self-describes the
> > 
> > > actual player behavior:
> > I'm all for keeping the name exclusive mode for WASAPI "exclusive mode".
> > The problem is that exclusive mode is *not* what the users want, and even
> > if it were, it's a WASAPI thing that would belong in the WASAPI plugin.
> 
> That is what my first patch was doing.

The first patch was literally enabling exclusive mode, but it was not doing so 
in the way that it's generally understood and meant for. Exclusive mode is 
meant to remove conversions, not to move conversions from the OS to the 
application.

> If we do that, we need an other option to disable all filters, this seems
> confusing.

I don't see how you can avoid it. First, you need to be able to disable filters 
and conversions without exclusive mode, e.g., for JACK because they are not 
always used together. And then, some audio outputs don't expose exclusive mode 
as a boolean flag, e.g., ALSA exposes it as a different output device set.

-- 
Реми Дёни-Курмон
http://www.remlab.net/