[alsa-devel] Output levels on SBLive! 5.1 on ALSA vs WIndows

[Takashi Iwai]

At Mon, 18 Jun 2007 17:37:46 +0800,
ChernYue Kwok wrote:
> 
> Hello,
> 
> I am using an SBLive! 5.1 sound card (emu10k1 chipset) with 6 channel output. 
> Due to the nature of my work, I need to be able to play sound through all 6 
> channels at the same output level to an amplifier.
> 
> Using Linux and the emu10k1 ALSA driver, I measured output voltage levels on 
> an oscilloscope while playing a sine wave on all 6 channels, and I got three 
> different output voltage amplitudes for the front, rear and center/subwoofer 
> channels.
> Repeating the same test with the same card on WIndows using the Creative 
> SBLive drivers from their website, I am able to get the same output voltage 
> amplitude on all 6 channels.
> For both tests, all output levels in the relevant mixers were set to their 
> maximum levels.
> 
> I would like to know if this output normalizing 'feature' of the SBLive 
> Windows driver can be found in the emu10k1 ALSA driver, or in any other ALSA 
> driver. Failing that, is there any other solution to set output levels in the 
> driver, or am I doomed to twiddle in alsamixer to get the output levels that 
> I want?

Did you check the dB level appearing in mixer?  The recent version of
ALSA shows dB level in alsamixer and amixer.  Note that the "Master"
and "PCM" controls are applied only for front channels.  So, set them
to 0dB and control the volume via Wave* digital mixers.


Takashi