Dave Seidel, Jul 31 2016:

> I have a Scarlett 18i8. When I run Csound, if I try to use the "dac:hw:x,0"
> device, I get messages like "Unable to set number of channels on soundcard"
> (with nchnls=2) or sometimes a similar message about setting the sample
> rate (usually 48000 or 96000). I always have to use "dac:plughw:x,0"
> instead. What is the difference, exactly?
Hi Dave,
I don't think you're sacrificing anything. the plug or plughw ALSA devices automatically try to convert between the incoming audio and the native settings of the interface. My card would always expect 12 channels of audio output, so ALSA manages that side and I get to simply send a stereo stream.

The plug and pluhw device types should be able to: manage different channel counts, convert bit resolution and resample. Although I'm not 100% sure about automatic resampling. If you're worried about that, see if your card has a setting for samplerate or read up on your cards supported samplerates and pick a supported one.
HTH.
...

Ta-ta,
----
Ffanci
* Homepage: https://freeshell.de/~silvain
* Twitter:  http://twitter.com/ffanci_silvain
* GitHub:   https://github.com/fsilvain

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Thanks, Ffanci.

On Sun, Jul 31, 2016 at 9:39 AM, Ffanci Silvain <silvain@freeshell.de> wrote:

Dave Seidel, Jul 31 2016:

I have a Scarlett 18i8. When I run Csound, if I try to use the "dac:hw:x,0"
device, I get messages like "Unable to set number of channels on soundcard"
(with nchnls=2) or sometimes a similar message about setting the sample
rate (usually 48000 or 96000). I always have to use "dac:plughw:x,0"
instead. What is the difference, exactly?

Hi Dave,
I don't think you're sacrificing anything. the plug or plughw ALSA devices automatically try to convert between the incoming audio and the native settings of the interface. My card would always expect 12 channels of audio output, so ALSA manages that side and I get to simply send a stereo stream.

The plug and pluhw device types should be able to: manage different channel counts, convert bit resolution and resample. Although I'm not 100% sure about automatic resampling. If you're worried about that, see if your card has a setting for samplerate or read up on your cards supported samplerates and pick a supported one.
HTH.
...

Ta-ta,
----
Ffanci
* Homepage: https://freeshell.de/~silvain
* Twitter:  http://twitter.com/ffanci_silvain
* GitHub:   https://github.com/fsilvain

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hi dave -

just to note that i had similar issues with audio cards and alsa.  after 
i used jack as "interface", all is fine ... (and jack gives several 
additional options)

best -
	joachim


On 31/07/16 17:30, Dave Seidel wrote:
> Thanks, Anders. Ffanci's answer and yours are reassuring. I would still
> like to eventually understand why I have to use the plug device with
> csound when I don't have to do this with other applications....
>
> On Sun, Jul 31, 2016 at 11:24 AM, Anders Genell  > wrote:
>
>     Just to add to Ffanci's fancy answer:
>      From answers to similar questions on the alsa users list I have
>     drawn the conclusion that the plug-device will handle resampling if
>     necessary, but will do nothing if the sound card can handle the
>     requested sample rate, so it should be safe to use.
>
>     Regards,
>     Anders
>
>     31 juli 2016 kl. 15:53 skrev Dave Seidel      >:
>
>>     Thanks, Ffanci.
>>
>>     On Sun, Jul 31, 2016 at 9:39 AM, Ffanci Silvain
>>     > wrote:
>>
>>         Dave Seidel, Jul 31 2016:
>>
>>             I have a Scarlett 18i8. When I run Csound, if I try to use
>>             the "dac:hw:x,0"
>>             device, I get messages like "Unable to set number of
>>             channels on soundcard"
>>             (with nchnls=2) or sometimes a similar message about
>>             setting the sample
>>             rate (usually 48000 or 96000). I always have to use
>>             "dac:plughw:x,0"
>>             instead. What is the difference, exactly?
>>
>>         Hi Dave,
>>         I don't think you're sacrificing anything. the plug or plughw
>>         ALSA devices automatically try to convert between the incoming
>>         audio and the native settings of the interface. My card would
>>         always expect 12 channels of audio output, so ALSA manages
>>         that side and I get to simply send a stereo stream.
>>
>>         The plug and pluhw device types should be able to: manage
>>         different channel counts, convert bit resolution and resample.
>>         Although I'm not 100% sure about automatic resampling. If
>>         you're worried about that, see if your card has a setting for
>>         samplerate or read up on your cards supported samplerates and
>>         pick a supported one.
>>         HTH.
>>         ...
>>
>>         Ta-ta,
>>         ----
>>         Ffanci
>>         * Homepage: https://freeshell.de/~silvain
>>         * Twitter: http://twitter.com/ffanci_silvain
>>         * GitHub: https://github.com/fsilvain
>>
>>         Csound mailing list
>>         Csound@listserv.heanet.ie 
>>         https://listserv.heanet.ie/cgi-bin/wa?A0=CSOUND
>>         Send bugs reports to
>>         https://github.com/csound/csound/issues
>>         Discussions of bugs and features can be posted here
>>
>>
>>     Csound mailing list Csound@listserv.heanet.ie
>>     
>>     https://listserv.heanet.ie/cgi-bin/wa?A0=CSOUND Send bugs reports
>>     to https://github.com/csound/csound/issues Discussions of bugs and
>>     features can be posted here
>     Csound mailing list Csound@listserv.heanet.ie
>     
>     https://listserv.heanet.ie/cgi-bin/wa?A0=CSOUND Send bugs reports to
>     https://github.com/csound/csound/issues Discussions of bugs and
>     features can be posted here
>
>
> Csound mailing list Csound@listserv.heanet.ie
> 
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> can be posted here

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