[LAU] Small instrument hardware module

Len Ovens len at ovenwerks.net
Wed Oct 22 03:36:55 UTC 2014

On Wed, 22 Oct 2014, Kazakore wrote:

> This is also what I was lead to believe. snd_hda_intel covers a fair range of different
> chips, each of which has its own characteristics and so there is no single answer to the
> original question. Pretty sure both my last two laptops were reported as snd_hda_intel
> and know they were definitely different sound chips! (Although offhand couldn't tell you
> what...)
> "Like AC'97, HD Audio is a specification that defines the architecture, link frame
> format, and programming interfaces used by the controller on the PCI bus and by the
> codec on the other side of the link. Implementations of the host controller are
> available from at least Intel, Nvidia, and AMD." [1]

Ok, that sounds prettier than what I said :)  the reason I called it a bus 
though is that one HDA interface seems to be able to handle a number of 
physical audio devices. Each of which can have a different bit depth and 
sample rate at the same time (say what?) so that the user could have a 
telephone handset hooked up to the interface at 32k/8bits while listening 
to/watching a high definition video. I don't know that Linux can handle 
this though. (or windows for that matter) I am just repeating some of the 
stuff I remember from reading though some of the very long and involved 
Intel Doc.

> Not sure if there is a mistake on the page or if my laptop actually has both of these
> for something?? [2]
> Intel 7 Series/C210 Series Chipset Family High Definition Audio Controller
> Intel Panther Point High Definition Audio Controller

It may have both on the same PCI IF even. cat /proc/interupts should tell 
I think. As a note. On my netbook, the audio IF can run at a number of 
sample rates with no problems, but my internal mic which shows up on the 
same ALSA device, can only run at 48k. That is the ADC for the internal 
mic only runs at 48k and if the rest of the internal audio (internal 
speakers, line in/out plugs, are set to 44.1k, those i/os will be fine, 
but the internal mic will have a periodic click as the 44.1 and 48k sample 
rates align and cycle past each other. The click goes away if the AI is 
set to 48K.

Be sure to look at the variety of HDA IF types the ALSA driver handles 
and all of the settings that can be given to the HDA driver. It is quite a 
long list.

Len Ovens

More information about the Linux-audio-user mailing list