About 'SNDRV_PCM_CLASS_MULTI' for devices with multi-channels

About 'SNDRV_PCM_CLASS_MULTI' for devices with multi-channels

[Takashi Sakamoto]

Hi all,

I have two questions about the usage of this macro.

Should I use this macro for new drivers which I'm working for?'
http://mailman.alsa-project.org/pipermail/alsa-devel/2014-January/071820.html

My drivers support some firewire devices, which is desinged for 
studio-use and have many channels. Its combination of channels are not 
designed for surround sound like 5.1ch.

Just judging from its name, 'SNDRV_PCM_CLASS_MULTI', I should use this.
But there are no drivers which use this macro in current tree, against 
my expectation that some drivers (ICE1712-pro, RME9652, 6fire usb and so 
on) should use this macro.

Are there any reasons?


Regards

Takashi Sakamoto
o-takashi@sakamocchi.jp

Re: About 'SNDRV_PCM_CLASS_MULTI' for devices with multi-channels

[David Henningsson]

On 02/19/2014 03:57 PM, Takashi Sakamoto wrote:
> Hi all,
> 
> I have two questions about the usage of this macro.
> 
> Should I use this macro for new drivers which I'm working for?'
> http://mailman.alsa-project.org/pipermail/alsa-devel/2014-January/071820.html
> 
> 
> My drivers support some firewire devices, which is desinged for
> studio-use and have many channels. Its combination of channels are not
> designed for surround sound like 5.1ch.
> 
> Just judging from its name, 'SNDRV_PCM_CLASS_MULTI', I should use this.
> But there are no drivers which use this macro in current tree, against
> my expectation that some drivers (ICE1712-pro, RME9652, 6fire usb and so
> on) should use this macro.
> 
> Are there any reasons?

I've never heard of it before. I had a quick look in alsa-lib and
couldn't find any difference in handling between CLASS_GENERIC and
CLASS_MULTI.

It's probably something historic that nobody uses any more. Maybe people
who have been along longer knows what it is.

-- 
David Henningsson, Canonical Ltd.
https://launchpad.net/~diwic

Re: About 'SNDRV_PCM_CLASS_MULTI' for devices with multi-channels

[Takashi Sakamoto]

Hi David,
(My message was not delivered by ALSA's mailman...)

Again all,

 >> I have two questions about the usage of this macro.
 >>
 >> Should I use this macro for new drivers which I'm working for?'
 >> 
http://mailman.alsa-project.org/pipermail/alsa-devel/2014-January/071820.html
 >>
 >>
 >> My drivers support some firewire devices, which is desinged for
 >> studio-use and have many channels. Its combination of channels are not
 >> designed for surround sound like 5.1ch.
 >>
 >> Just judging from its name, 'SNDRV_PCM_CLASS_MULTI', I should use this.
 >> But there are no drivers which use this macro in current tree, against
 >> my expectation that some drivers (ICE1712-pro, RME9652, 6fire usb and so
 >> on) should use this macro.
 >>
 >> Are there any reasons?

In current tree, there are no drivers which uses this macro.

As long as I investigated in ftp server, this macro is firstly added in 
ALSA 0.9.0beta1 (2001/02/21). So this macro has been ignored over 10 
years...


Regards

Takashi Sakamoto
o-takashi@sakamocchi.jp

Re: About 'SNDRV_PCM_CLASS_MULTI' for devices with multi-channels

[Takashi Iwai]

At Thu, 20 Feb 2014 11:28:48 +0900,
Takashi Sakamoto wrote:
> 
> Hi David,
> (My message was not delivered by ALSA's mailman...)

Because you posted from an address that isn't subscribed.
It takes time until manually approved.

> Again all,
> 
>  >> I have two questions about the usage of this macro.
>  >>
>  >> Should I use this macro for new drivers which I'm working for?'
>  >> 
> http://mailman.alsa-project.org/pipermail/alsa-devel/2014-January/071820.html
>  >>
>  >>
>  >> My drivers support some firewire devices, which is desinged for
>  >> studio-use and have many channels. Its combination of channels are not
>  >> designed for surround sound like 5.1ch.
>  >>
>  >> Just judging from its name, 'SNDRV_PCM_CLASS_MULTI', I should use this.
>  >> But there are no drivers which use this macro in current tree, against
>  >> my expectation that some drivers (ICE1712-pro, RME9652, 6fire usb and so
>  >> on) should use this macro.
>  >>
>  >> Are there any reasons?
> 
> In current tree, there are no drivers which uses this macro.
> 
> As long as I investigated in ftp server, this macro is firstly added in 
> ALSA 0.9.0beta1 (2001/02/21). So this macro has been ignored over 10 
> years...

Right.  And the likely reason is that such a differentiation doesn't
help much.  You can still use your device for driving 5.1 surround :)

So, I rather would like to keep them RIP.  Maybe worth to remove it
now.


Takashi

Re: About 'SNDRV_PCM_CLASS_MULTI' for devices with multi-channels

[Takashi Sakamoto]

> Right.  And the likely reason is that such a differentiation doesn't
> help much.

I thought usage of this macro can tell applications that the PCM 
channels are not for surround sound.

But for this purpose, card configuration is better. Applications can get 
to know by seeking 'surround' PCM devices such like 'surround51'.

 > You can still use your device for driving 5.1 surround :)

It's not my intention. I'm considering about the way to prevent 
applications from using the devices for surround sound.

I don't prepare for card configuration. So devices which my drivers 
support have no 'surround' PCM devices.

 > So, I rather would like to keep them RIP. Maybe worth to remove it
 > now.

Yes.

In the same reason, 'SND_PCM_SUBCLASS_MULTI_MIX' should be removed. As a 
result, 'SND_PCM_SUBCLASS_XXX', 'struct snd_pcm_info.dev_subclass' are 
also needless...


Thanks

Takashi Sakamoto
o-takashi@sakamocchi.jp

About 'SNDRV_PCM_CLASS_MULTI' for devices with multi-channels

[Takashi Sakamoto]

Hi all,

I have two questions about the usage of this macro.

Should I use this macro for new drivers which I'm working for?'
http://mailman.alsa-project.org/pipermail/alsa-devel/2014-January/071820.html

My drivers support some firewire devices, which is desinged for 
studio-use and have many channels. Its combination of channels are not 
designed for surround sound like 5.1ch.

Just judging from its name, 'SNDRV_PCM_CLASS_MULTI', I should use this.
But there are no drivers which use this macro in current tree, against 
my expectation that some drivers (ICE1712-pro, RME9652, 6fire usb and so 
on) should use this macro.

Are there any reasons?


Regards

Takashi Sakamoto
o-takashi@sakamocchi.jp

About 'SNDRV_PCM_CLASS_MULTI' for devices with multi-channels

[Takashi Sakamoto]

Hi all,

I have two questions about the usage of this macro.

Should I use this macro for new drivers which I'm working for?'
http://mailman.alsa-project.org/pipermail/alsa-devel/2014-January/071820.html

My drivers support some firewire devices, which is desinged for studio-use and have many channels. Its combination of channels are not designed for surround sound like 5.1ch.

Just judging from its name, 'SNDRV_PCM_CLASS_MULTI', I should use this.
But there are no drivers which use this macro in current tree, against my expectation that some drivers (ICE1712-pro, RME9652, 6fire usb and so on) should use this macro.

Are there any reasons?


Regards

Takashi Sakamoto
o-takashi@sakamocchi.jp

About 'SNDRV_PCM_CLASS_MULTI' for devices with multi-channels

[Takashi Sakamoto]

Hi all,

I have two questions about the usage of this macro.

Should I use this macro for new drivers which I'm working for?'
http://mailman.alsa-project.org/pipermail/alsa-devel/2014-January/071820.html

My drivers support some firewire devices, which is desinged for 
studio-use and have many channels. Its combination of channels are not 
designed for surround sound like 5.1ch.

Just judging from its name, 'SNDRV_PCM_CLASS_MULTI', I should use this.
But there are no drivers which use this macro in current tree, against 
my expectation that some drivers (ICE1712-pro, RME9652, 6fire usb and so 
on) should use this macro.

Are there any reasons?


Regards

Takashi Sakamoto
o-takashi@sakamocchi.jp

About 'SNDRV_PCM_CLASS_MULTI' for devices with multi-channels

[Takashi Sakamoto]

Hi all,

I have two questions about the usage of this macro.

Should I use this macro for new drivers which I'm working for?'
http://mailman.alsa-project.org/pipermail/alsa-devel/2014-January/071820.html

My drivers support some firewire devices, which is desinged for 
studio-use and have many channels. Its combination of channels are not 
designed for surround sound like 5.1ch.

Just judging from its name, 'SNDRV_PCM_CLASS_MULTI', I should use this.
But there are no drivers which use this macro in current tree, against 
my expectation that some drivers (ICE1712-pro, RME9652, 6fire usb and so 
on) should use this macro.

Are there any reasons?


Regards

Takashi Sakamoto
o-takashi@sakamocchi.jp