30 Jan
2010
30 Jan
'10
1:38 p.m.
Clemens Ladisch wrote:
Most likely users won't care as long as it works (at least that's
how I
look at things I didn't develop myself). The challenge will therefore be
to ensure that both systems can co-exist.
I can see the bug report: "I started both Jack+firewire and some ALSA
program, but the output wasn't properly mixed." ;-)
The horror...
Personally I would not mind to use ALSA for all the streaming (and mixer
control for that matter) if it is up for it. The user support of
parallel implementations is simply too much work. But it might take some
time for that to happen (as we also have e.g. MOTU and RME streaming
protocols to take care off).
The same goes for mixer control and maybe even device discovery: if it
can be built upon ALSA, why not? I'm personally a bit skeptical about
whether you'd want (or get) the required code for this into the kernel
though. Especially for BeBoB devices its a significant.
Maximum user experience with minimal effort is what I'd like to see, and
if I have to ditch all of the current FFADO code, so be it. Linux audio
is enough of a mess already.
Greets,
Pieter
Pieter Palmers wrote:
If Jack cannot fix a xrun immediately by restarting, it dies. If the
device stays unplugged, waiting indefinitely for it to reappear would
make no sense. This cannot be handled without asking the user.
To me it makes perfect sense. I unplug the device, jack keeps running in
"dummy mode", I re-plug the device and we're good to go. Why would jack
have to die? Even more: I plug in another device and it shows up as a
new interface in the jack graph. Just like what happens if I start a new
jack client.
Note that I make abstraction of the technical implementation here, this
is merely the perspective of an end-user who couldn't care less about
technical details.
Talking about mixer controls: do you intend to
expose all mixer controls
Yes.
to ALSA,
x*y monitoring controls would suck in a 'normal' mixer application.
or would a custom application still be the way to
go for mixers?
Yes. In theory, it shouldn't be difficult to make the existing (if any)
custom mixer work with both drivers.
Can ALSA handle mixer capabilities that change
with changing device
configurations?
Yes; mixer controls can be changed, created and destroyed at runtime.
Hotplugging and device aggregation should work just fine, although not
both together, i.e., ALSA doesn't allow changing the stream format while
the stream is running. Is this possible with FFADO+Jack?
With the current version
of FFADO this is not possible as bus resets are
not handled properly. But there is no technical reason that prevents
this. Jack ports can be created and destroyed at run-time, and that's
all it takes.
The major use-case I'm thinking of is where a user inadvertently unplugs
the device. With current FFADO this is a show stopper, but I'd like to
see a system that keeps running and restores everything once the device
is re-attached. So maybe you should worry more about the confusion
that might cause...
While potential users might disagree, I think more choice is
better.