[alsa-devel] alsactl adds volume controls?

[Colin Guthrie]

'Twas brillig, and Raymond Yau at 04/10/10 12:09 did gyre and gimble:
> 2010/10/1 Clemens Ladisch <clemens at ladisch.de>
> 
>> Takashi Iwai wrote:
>>> Mark Brown wrote:
>>>> On Thu, Sep 30, 2010 at 04:09:56PM +0100, Colin Guthrie wrote:
>>>>> *shouldn't* use them, but at present it does and they *are* active
>> and
>>>>> used, so it's not an issue for me), the problem is rather one of
>> setting
>>>>> Master (not PCM) to 0% aka -46.5dB causes some kind of auto-mute that
>>>>> cuts off all sound. It shouldn't do that.
>>>>
>>>> Is this perhaps just an error in the TLV information - should it be
>>>> flagging that the minimim gain is mute but isn't?
>>>
>>> There is no clear (or consistent) definition in HD-audio codec, I guess.
>>
>> The HDA spec is quite clear that muting is done only with the mute bit.
>>
>>> Some chips do mute at 0 and some not.
>>
>> Those that do are violating the specification.
>>
>> But we have to support them anyway.
>> Colin, please tell us the IDs of your codec so that we can add a TLV
>> workaround to the driver.
>>
>>
>> Regards,
>> Clemens
>>
>>
> Actually, the softvol plugin behave as the same way as Colin describe since
> when the resolution is 2 , the softvol become a mute switch
> 
> http://git.alsa-project.org/?p=alsa-lib.git;a=commit;h=f78af4ab0412052aabb74c9122a8d8f3ab6d45e6
> 
> So the question is why -51dB is selected as min_dB
> 
> Is this value enough for S16_LE or  S32_LE for hda-intel ?
> 
> http://git.alsa-project.org/?p=alsa-kernel.git;a=commitdiff;h=eacbb9dba6b4c982a0217ea2c7d15db88d4fda37;hp=d91b424d6d7bda0773b6b6b606d48d089c4f5115
> 
> As those DACs support -120dB to 0dB , but the driver can actually limit the
> dB range to -60dB to 0dB . so the minimum volume -60dB is definitly not mute
> in this case
> 
> why -60dB is selected  ?


Just for clarity, the 0 -> -51dB range is for the PCM control (i.e.
softvol) only. The Master control gives me -46.5dB in addtiion to that
giving a total of -97.5dB. This still isn't as high as the -120dB you
are mentioning, but it's a lot closer.

Of course I am lucky in that my Master apparently works fine but for
those souls without any Master control, I presume the full range should
be offered by the PCM softvol?

Col

-- 

Colin Guthrie
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http://colin.guthr.ie/

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