different between "default" and "hw:0,0"?

different between "default" and "hw:0,0"?

[\x05]

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Hi all,
I'm new to alsa, and get some confused with "default" device and and the
"hw:0,0" device, do they have any difference?
i write a very simple media player app, using xine-lib, i modify the
xine config file, set the "audio.device.alsa_front_device" value to
"hw:0,0". 
i found that, when the value is "hw:0,0", the program can NOT run more
than one process at same time(I mean only one process can play
sound,others hang),
when the value set to "default", i can run more than one process, and
every app can play sound at same time.
so, it seems that, the "default" and he "hw0,0" are not same, and i
don't know the detail.

can anybody help me? thanks a lot!
Bhpan 




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Re: different between "default" and "hw:0,0"?

[Lee Revell]

On Tue, 2006-11-28 at 13:26 +0800, \x05 wrote:
> Hi all,
> I'm new to alsa, and get some confused with "default" device and and the
> "hw:0,0" device, do they have any difference?
> i write a very simple media player app, using xine-lib, i modify the
> xine config file, set the "audio.device.alsa_front_device" value to
> "hw:0,0". 
> i found that, when the value is "hw:0,0", the program can NOT run more
> than one process at same time(I mean only one process can play
> sound,others hang),
> when the value set to "default", i can run more than one process, and
> every app can play sound at same time.
> so, it seems that, the "default" and he "hw0,0" are not same, and i
> don't know the detail.

Using the hw device bypasses ALSA's software mixing layer and thus only
one app can play at a time.  Apps should always use "default" unless you
know what you are doing.

Lee


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Re: different between "default" and "hw:0,0"?

[Oliver Schinagl]

This would only apply to the PCM/data side of Alsa right? Not the 
control/mixer part, as from what I gatherd from the alsa wiki, 'default' 
is just a name for card 0.

Other than that, how can I still use software mixing, but force an 
application to use hw1 instead of hw0?

Lee Revell wrote:
> On Tue, 2006-11-28 at 13:26 +0800, \x05 wrote:
>   
>> Hi all,
>> I'm new to alsa, and get some confused with "default" device and and the
>> "hw:0,0" device, do they have any difference?
>> i write a very simple media player app, using xine-lib, i modify the
>> xine config file, set the "audio.device.alsa_front_device" value to
>> "hw:0,0". 
>> i found that, when the value is "hw:0,0", the program can NOT run more
>> than one process at same time(I mean only one process can play
>> sound,others hang),
>> when the value set to "default", i can run more than one process, and
>> every app can play sound at same time.
>> so, it seems that, the "default" and he "hw0,0" are not same, and i
>> don't know the detail.
>>     
>
> Using the hw device bypasses ALSA's software mixing layer and thus only
> one app can play at a time.  Apps should always use "default" unless you
> know what you are doing.
>
> Lee
>
>
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> Alsa-devel mailing list
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>   

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Re: different between "default" and "hw:0,0"?

[Lee Revell]

On Tue, 2006-11-28 at 17:57 +0100, Oliver Schinagl wrote:
> This would only apply to the PCM/data side of Alsa right? Not the 
> control/mixer part, as from what I gatherd from the alsa wiki, 'default' 
> is just a name for card 0.
> 
> Other than that, how can I still use software mixing, but force an 
> application to use hw1 instead of hw0?

No, default just refers to the default PCM, not the default card.  The
full device name is default:X where X is the card number.  The card
number just defaults to 0 if you don't specify it.

To use the default PCM of card 1, your app should use "default:1".

Lee



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