Hi,
Some ideas, proposal for further discussion...
On Mon, 5 Oct 2009, Stefan Schmidt wrote:
> Hello.
>
> On Mon, 2009-10-05 at 11:14, Jaroslav Kysela wrote:
>> On Mon, 5 Oct 2009, Stefan Schmidt wrote:
>>
>>> On Thu, 2009-10-01 at 17:08, Stefan Schmidt wrote:
>>>>
>>>> For an updated patch with all your comments inlcuded see below.
>>>
>>> Here is another update on this patch. Fixed a problem I introduced in the last
>>> iteration and changed the config tokens from MasterPlaybackVolume to Master
>>> Playback Volume, etc. That's based on a siggestion from Mark which we had
>>> offlist. Let me quote it here to explain the good reasoning behind it.
>>
>> Question: What's the IDs (integers) returned with
>> snd_scenario_get_master_playback_volume() etc. functions?
>
> That is part of the code Liam wrote, but let me answer it (and maybe
> Liam chime in if it is wrong or needs more explanation).
>
> It's just the numid of an alsa control which should be used as master
> playback, etc in this scenario. It aliases the function we can use with
> ascenario to the real ones in alsa which can bedifferent for different
> scenarios.
It's not very clear. The exported functions should be documented at least
with doxygen.
Also, I would move all _get_ functions to one with this interface:
#define SND_SCENARIO_KEY_KCTL_MASTER_PLAYBACK_VOLUME 1
.....
int snd_scenario_get(scenario, int key, void *result);
It will allow us to extend this interface without adding many functions in
future, something like:
#define SND_SCENARIO_KEY_PCM_PLAYBACK 11
.....
Also, using numid's is not much ideal if something changes in the driver.
I would prefer to use standard ctl IDs (string, index, interface -
result should be snd_ctl_elem_id_t).
>> Please, include also some test configuration files to review the
>> configurationsyntax.
>
> Attached. default.conf is the main configuration file located at
> /etc/alsa/scenario/default.conf
Again, I would make configuration syntax compatible with other alsa-lib
configuration files. The changes in the configuration files will be small
and it will allow us to rewrite the code using parsers in alsa-lib.
Something like:
default.conf:
scenario."playback speaker" {
file playback_spk
qos HIFI
"Master Playback Volume" 8
# should be rather something like:
kcontrol.'Master Playback Volume' "'Master Playback Volume':33"
# or a short form might be implemented (:33 is ctl_id index, ctl_id.name
# would be copied from the variable key name):
kcontrol.'Master Playback Volume' ":33"
...
}
scenario."playback headphones" {
...
}
About "playback_hs_*" files. It seems that the purpose of files is quite
similar. I don't understand the reason to have 2 different descriptions.
Also, I would like to consider moving the parser from alsactl
initialization code (see alsactl_init.c in alsa-utils package) to alsa-lib
and use this parser also for these files. It gives much flexibility,
although udev-like syntax is not ideal, I know. But we have full
documentation in alsactl_init.xml, at least.
Jaroslav
-----
Jaroslav Kysela <perex@xxxxxxxx>
Linux Kernel Sound Maintainer
ALSA Project, Red Hat, Inc.
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