Hi Clemens,
On 02/21/2015 04:41 PM, Clemens Ladisch wrote:
> Nikolay Dimitrov wrote:
>> On 02/20/2015 01:35 PM, Clemens Ladisch wrote:
>>> pcm.copy_to_hw0 {
>>> type copy
>>> slave.pcm "hw:0"
>>> }
>>>
>>> The device "copy_to_hw0" just copies everything to hw:0.
>>
>> Well, part of my issue is my understanding of "copying" - it's usually
>> done from a source to a destination, and in this specific case I just
>> fail to understand which is the source and how it's declared in the
>> config.
>
> The source is the "copy_to_hw0" device (or the application using it).
I'm by no means expert in ALSA config files, but what I understand from
the documentation is that in this case "copy_to_hw0" is the name of the
plugin instance. So "copy_to_hw0" looks to me just like an alias to
"hw:0".
>> I can give you an example why "everything" seems fuzzy to my. If I use
>> a "plug" plugin to adapt audio formats to my audio device, or if I use
>> "dmix" plugin to mix multiple audio streams, which exact stream will
>> qualify as "everything" so it can be copied by the "copy" plugin - the
>> ones before or after the mixing, or the one before or after the format
>> conversion?
>
> That depends.
>
> Filter-type plugins like "plug" or "copy" have a 'slave' device; in the
> case of playback devices, this is the destination. Any plugin can be
> the slave of another plugin. ("hw" does not have a slave; "multi" has
> multiple ones; "dmix" can only use "hw" as slave.)
Yep, I tried to extend your nice example to support sharing across
multiple applications, but there seems to have some limitations about
how plugins can be connected together, and I still hadn't had success
in making "multi" talking to "dmix".
Regards,
Nikolay
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